Programs & Examples On #Compiler errors

An error that is generated during the compilation phase, often due to problems with invalid syntax and/or types. Compare to [runtime-error].

Extension methods must be defined in a non-generic static class

I encountered a similar issue, I created a 'foo' folder and created a "class" inside foo, then I get the aforementioned error. One fix is to add "static" as earlier mentioned to the class which will be "public static class LinqHelper".

My assumption is that when you create a class inside the foo folder it regards it as an extension class, hence the following inter alia rule apply to it:

1) Every extension method must be a static method

WORKAROUND If you don't want static. My workaround was to create a class directly under the namespace and then drag it to the "foo" folder.

C++ error: "Array must be initialized with a brace enclosed initializer"

The syntax to statically initialize an array uses curly braces, like this:

int array[10] = { 0 };

This will zero-initialize the array.

For multi-dimensional arrays, you need nested curly braces, like this:

int cipher[Array_size][Array_size]= { { 0 } };

Note that Array_size must be a compile-time constant for this to work. If Array_size is not known at compile-time, you must use dynamic initialization. (Preferably, an std::vector).

Why is this program erroneously rejected by three C++ compilers?

You need to specify the precision of your output preceded by a colon immediately before the final closing brace. Since the output is not numeric, the precision is zero, so you need this-

:0}

Could not load file or assembly ... The parameter is incorrect

I had the same issue here - above solutions didn't work. Problem was with ActionMailer. I ran the following uninstall and install nuget commands

uninstall-package ActionMailer
install-package ActionMailer

Resolved my problems, hopefully will help someone else.

what does "error : a nonstatic member reference must be relative to a specific object" mean?

CPMSifDlg::EncodeAndSend() method is declared as non-static and thus it must be called using an object of CPMSifDlg. e.g.

CPMSifDlg obj;
return obj.EncodeAndSend(firstName, lastName, roomNumber, userId, userFirstName, userLastName);

If EncodeAndSend doesn't use/relate any specifics of an object (i.e. this) but general for the class CPMSifDlg then declare it as static:

class CPMSifDlg {
...
  static int EncodeAndSend(...);
  ^^^^^^
};

Compile error: package javax.servlet does not exist

Even after trying suggested solution, it was not solving my problem because there where many instance of java path were entered by me.

  1. I removed all java related path (different version java) from "Path, JAVA_HOME, JRE_HOME" and created from fresh.

  2. i have set (path may changes as per different installation)
    a. JAVA_HOME as C:\Program Files\Java\jdk1.8.0_191
    b. JRE_HOME as C:\Program Files\Java\jdk1.8.0_191\jre\lib
    c. add binary file path in path: C:\Program Files\Java\jdk1.8.0_191\bin
    d. CLASSPATH as C:\apache-tomcat-7.0.93\lib

  3. never try in the same command prompt if its already open while doing changes/creting system/user variables. close it and open new one.

Reference Image: enter image description here

"Undefined reference to" template class constructor

You will have to define the functions inside your header file.
You cannot separate definition of template functions in to the source file and declarations in to header file.

When a template is used in a way that triggers its intstantation, a compiler needs to see that particular templates definition. This is the reason templates are often defined in the header file in which they are declared.

Reference:
C++03 standard, § 14.7.2.4:

The definition of a non-exported function template, a non-exported member function template, or a non-exported member function or static data member of a class template shall be present in every translation unit in which it is explicitly instantiated.

EDIT:
To clarify the discussion on the comments:
Technically, there are three ways to get around this linking problem:

  • To move the definition to the .h file
  • Add explicit instantiations in the .cpp file.
  • #include the .cpp file defining the template at the .cpp file using the template.

Each of them have their pros and cons,

Moving the defintions to header files may increase the code size(modern day compilers can avoid this) but will increase the compilation time for sure.

Using the explicit instantiation approach is moving back on to traditional macro like approach.Another disadvantage is that it is necessary to know which template types are needed by the program. For a simple program this is easy but for complicated program this becomes difficult to determine in advance.

While including cpp files is confusing at the same time shares the problems of both above approaches.

I find first method the easiest to follow and implement and hence advocte using it.

invalid types 'int[int]' for array subscript

int myArray[10][10][10];

should be

int myArray[10][10][10][10];

Non-static variable cannot be referenced from a static context

This is bit diff to explain about static key word for all beginners.
You wil get to know it clearly when you work more with Classes and Objects.

|*| Static : Static items can be called with Class Name
If you observe in codes, Some functions are directly called with Class names like

NamCls.NamFnc();

System.out.println();

This is because NamFnc and println wil be declared using key word static before them.

|*| Non Static :Non Static items can be called with Class Variable
If its not static, you need a variable of the class,
put dot after the class variable and
then call function.

NamCls NamObjVar = new NamCls();
NamObjVar.NamFnc();


Below code explains you neatly

|*| Static and non Static function in class :

public class NamCls
{
    public static void main(String[] args)
    {
        PlsPrnFnc("Tst Txt");

        NamCls NamObjVar = new NamCls();
        NamObjVar.PrnFnc("Tst Txt");
    }

    static void PlsPrnFnc(String SrgPsgVal)
    {
        System.out.println(SrgPsgVal);
    }

    void PrnFnc(String SrgPsgVal)
    {
        System.out.println(SrgPsgVal);
    }
}


|*| Static and non Static Class inside a Class :

public class NamCls
{
    public static void main(String[] args)
    {
        NamTicCls NamTicVaj = new NamTicCls();
        NamTicVaj.PrnFnc("Tst Txt");

        NamCls NamObjVar = new NamCls();
        NamNicCls NamNicVar = NamObjVar.new NamNicCls();
        NamNicVar.PrnFnc("Tst Txt");
    }

    static class NamTicCls
    {
        void PrnFnc(String SrgPsgVal)
        {
            System.out.println(SrgPsgVal);
        }
    }

    class NamNicCls
    {
        void PrnFnc(String SrgPsgVal)
        {
            System.out.println(SrgPsgVal);
        }
    }
}

libpthread.so.0: error adding symbols: DSO missing from command line

Try to add -pthread at the end of the library list in the Makefile.

It worked for me.

How to compile Go program consisting of multiple files?

Yup! That's very straight forward and that's where the package strategy comes into play. there are three ways to my knowledge. folder structure:

GOPATH/src/ github.com/ abc/ myproject/ adapter/ main.go pkg1 pkg2 warning: adapter can contain package main only and sun directories

  1. navigate to "adapter" folder. Run:
    go build main.go
  1. navigate to "adapter" folder. Run:
    go build main.go
  1. navigate to GOPATH/src recognize relative path to package main, here "myproject/adapter". Run:
    go build myproject/adapter

exe file will be created at the directory you are currently at.

The located assembly's manifest definition does not match the assembly reference

In my case, this error occurred while running an ASP.NET application. The solution was to:

  1. Delete the obj and bin folders in the project folder

Clean didn't work, rebuild didn't work, all references were fine, but it wasn't writing one of the libraries. After deleting those directories, everything worked perfectly.

How to fix "unable to open stdio.h in Turbo C" error?

Do this: Open your turboc2 folder you have tc.exe file inside, beside this file you find another file as named as ' tcinst.exe ' open it.

You will see the installation menu:

select as-- > Option > Directory > Include directory

Here you have to change the path of the directory to the path where your INCLUDE folder is located. Same way change the path to library directory also over restart your tc.exe.

Java Error: illegal start of expression

Declare

public static int[] locations={1,2,3};

outside of the main method.

Trying to include a library, but keep getting 'undefined reference to' messages

If the .c source files are converted .cpp (like as in parsec), then the extern needs to be followed by "C" as in

extern "C" void foo();

Java compile error: "reached end of file while parsing }"

You need to enclose your class in { and }. A few extra pointers: According to the Java coding conventions, you should

  • Put your { on the same line as the method declaration:
  • Name your classes using CamelCase (with initial capital letter)
  • Name your methods using camelCase (with small initial letter)

Here's how I would write it:

public class ModMyMod extends BaseMod {

    public String version() {
         return "1.2_02";
    }

    public void addRecipes(CraftingManager recipes) {
       recipes.addRecipe(new ItemStack(Item.diamond), new Object[] {
          "#", Character.valueOf('#'), Block.dirt
       });
    }
}

ServletException, HttpServletResponse and HttpServletRequest cannot be resolved to a type

You can do the folllwoing: import the jar file inside you class:

import javax.servlet.http.HttpServletResponse

add the Apache Tomcat library as follow:

Project > Properties > Java Build Path > Libraries > Add library from library tab > Choose server runtime > Next > choose Apache Tomcat v 6.0 > Finish > Ok

Also First of all, make sure that Servlet jar is included in your class path in eclipse as PermGenError said.

I think this will solve your error

What is an 'undeclared identifier' error and how do I fix it?

I had the same problem with a custom class, which was defined in a namespace. I tried to use the class without the namespace, causing the compiler error "identifier "MyClass" is undefined". Adding

using namespace <MyNamespace>

or using the class like

MyNamespace::MyClass myClass;

solved the problem.

Non-Static method cannot be referenced from a static context with methods and variables

You need to make both your method - printMenu() and getUserChoice() static, as you are directly invoking them from your static main method, without creating an instance of the class, those methods are defined in. And you cannot invoke a non-static method without any reference to an instance of the class they are defined in.

Alternatively you can change the method invocation part to:

BookStoreApp2 bookStoreApp = new BookStoreApp2();
bookStoreApp.printMenu();
bookStoreApp.getUserChoice();

Compilation error - missing zlib.h

I also had the same problem. Then I installed the zlib, still the problem remained the same. Then I added the following lines in my .bashrc and it worked. You should replace the path with your zlib installation path. (I didn't have root privileges).

export PATH =$PATH:$HOME/Softwares/library/Zlib/zlib-1.2.11/
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/Softwares/library/Zlib/zlib-1.2.11/lib/
export LIBRARY_PATH=$LIBRARY_PATH:$HOME/Softwares/library/Zlib/zlib-1.2.11/lib/
export C_INCLUDE_PATH=$HOME/Softwares/library/Zlib/zlib-1.2.11/include/
export CPLUS_INCLUDE_PATH=$HOME/Softwares/library/Zlib/zlib-1.2.11/include/
export PKG_CONFIG_PATH=$HOME/Softwares/library/Zlib/zlib-1.2.11/lib/pkgconfig

C# Error: Parent does not contain a constructor that takes 0 arguments

You need to change the constructor of the child class to this:

public child(int i) : base(i)
{
    Console.WriteLine("child");
}

The part : base(i) means that the constructor of the base class with one int parameter should be used. If this is missing, you are implicitly telling the compiler to use the default constructor without parameters. Because no such constructor exists in the base class it is giving you this error.

invalid new-expression of abstract class type

invalid new-expression of abstract class type 'box'

There is nothing unclear about the error message. Your class box has at least one member that is not implemented, which means it is abstract. You cannot instantiate an abstract class.

If this is a bug, fix your box class by implementing the missing member(s).

If it's by design, derive from box, implement the missing member(s) and use the derived class.

error MSB6006: "cmd.exe" exited with code 1

When working with a version control system where all files are read only until checked out (like Perforce), the problem may be that you accidentally submitted into this version control system one of the VS files (like filters, for example) and the file thus cannot be overridden during build.

Just go to your working directory and check that none of VS solution related files and none of temporary created files (like all moc_ and ui_ prefixed files in QT, for example) is read only.

error: expected primary-expression before ')' token (C)

A function call needs to be performed with objects. You are doing the equivalent of this:

// function declaration/definition
void foo(int) {}

// function call
foo(int); // wat!??

i.e. passing a type where an object is required. This makes no sense in C or C++. You need to be doing

int i = 42;
foo(i);

or

foo(42);

"Are you missing an assembly reference?" compile error - Visual Studio

In my case, I had to change the Copy Local setting to true (right-click assembly in solution explorer, select properties, locate and change value of Copy Local property). Once this setting was changed, publication of my WCF service copied the file to the server and the error went away.

(.text+0x20): undefined reference to `main' and undefined reference to function

This error means that, while linking, compiler is not able to find the definition of main() function anywhere.

In your makefile, the main rule will expand to something like this.

main: producer.o consumer.o AddRemove.o
   gcc -pthread -Wall -o producer.o consumer.o AddRemove.o

As per the gcc manual page, the use of -o switch is as below

-o file     Place output in file file. This applies regardless to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code. If -o is not specified, the default is to put an executable file in a.out.

It means, gcc will put the output in the filename provided immediate next to -o switch. So, here instead of linking all the .o files together and creating the binary [main, in your case], its creating the binary as producer.o, linking the other .o files. Please correct that.

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Collections.Generic.List<string>

If you have source as a string like "abcd" and want to produce a list like this:

{ "a.a" },
{ "b.b" },
{ "c.c" },
{ "d.d" }

then call:

List<string> list = source.Select(c => String.Concat(c, ".", c)).ToList();

Python: No acceptable C compiler found in $PATH when installing python

for Ubuntu / Debian :

# sudo apt-get install build-essential

For RHEL/CentOS

#rpm -qa | grep gcc
# yum install gcc glibc glibc-common gd gd-devel -y

or

 # yum groupinstall "Development tools" -y

More details refer the link

extra qualification error in C++

Are you putting this line inside the class declaration? In that case you should remove the JSONDeserializer::.

How to view the list of compile errors in IntelliJ?

A more up to date answer for anyone else who comes across this:

(from https://www.jetbrains.com/help/idea/eclipse.html, §Auto-compilation; click for screenshots)

Compile automatically:

To enable automatic compilation, navigate to Settings/Preferences | Build, Execution, Deployment | Compiler and select the Build project automatically option

Show all errors in one place:

The Problems tool window appears if the Make project automatically option is enabled in the Compiler settings. It shows a list of problems that were detected on project compilation.

Use the Eclipse compiler: This is actually bundled in IntelliJ. It gives much more useful error messages, in my opinion, and, according to this blog, it's much faster since it was designed to run in the background of an IDE and uses incremental compilation.

While Eclipse uses its own compiler, IntelliJ IDEA uses the javac compiler bundled with the project JDK. If you must use the Eclipse compiler, navigate to Settings/Preferences | Build, Execution, Deployment | Compiler | Java Compiler and select it... The biggest difference between the Eclipse and javac compilers is that the Eclipse compiler is more tolerant to errors, and sometimes lets you run code that doesn't compile.

Deserialize JSON with Jackson into Polymorphic Types - A Complete Example is giving me a compile error

If using the fasterxml then,

these changes might be needed

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.Version;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.node.ObjectNode;

in main method--

use

SimpleModule module =
  new SimpleModule("PolymorphicAnimalDeserializerModule");

instead of

new SimpleModule("PolymorphicAnimalDeserializerModule",
      new Version(1, 0, 0, null));

and in Animal deserialize() function, make below changes

//Iterator<Entry<String, JsonNode>> elementsIterator =  root.getFields();
Iterator<Entry<String, JsonNode>> elementsIterator = root.fields();

//return mapper.readValue(root, animalClass);
return  mapper.convertValue(root, animalClass); 

This works for fasterxml.jackson. If it still complains of the class fields. Use the same format as in the json for the field names (with "_" -underscore). as this
//mapper.setPropertyNamingStrategy(new CamelCaseNamingStrategy()); might not be supported.

abstract class Animal
{
  public String name;
}

class Dog extends Animal
{
  public String breed;
  public String leash_color;
}

class Cat extends Animal
{
  public String favorite_toy;
}

class Bird extends Animal
{
  public String wing_span;
  public String preferred_food;
}

dereferencing pointer to incomplete type

Outside of possible scenarios involving whole-program optimization, the code code generated for something like:

struct foo *bar;
struct foo *test(struct foo *whatever, int blah)
{
  return blah ? whatever: bar;
}

will be totally unaffected by what members struct foo might contain. Because make utilities will generally recompile any compilation unit in which the complete definition of a structure appears, even when such changes couldn't actually affect the code generated for them, it's common to omit complete structure definitions from compilation units that don't actually need them, and such omission is generally not worthy of a warning.

A compiler needs to have a complete structure or union definition to know how to handle declarations objects of the type with automatic or static duration, declarations of aggregates containing members of the type, or code which accesses members of the structure or union. If the compiler doesn't have the information needed to perform one of the above operations, it will have no choice but to squawk about it.

Incidentally, there's one more situation where the Standard would allow a compiler to require a complete union definition to be visible but would not require a diagnostic: if two structures start with a Common Initial Sequence, and a union type containing both is visible when the compiler is processing code that uses a pointer of one of the structure types to inspects a member of that Common Initial Sequence, the compiler is required to recognize that such code might be accessing the corresponding member of a structure of the other type. I don't know what compilers if any comply with the Standard when the complete union type is visible but not when it isn't [gcc is prone to generate non-conforming code in either case unless the -fno-strict-aliasing flag is used, in which case it will generate conforming code in both cases] but if one wants to write code that uses the CIS rule in such a fashion as to guarantee correct behavior on conforming compilers, one may need to ensure that complete union type definition is visible; failure to do so may result in a compiler silently generating bogus code.

Maven error :Perhaps you are running on a JRE rather than a JDK?

I had the same error and I was missing the User variable: JAVA_HOME and the value for the SDK - "C:\Program Files\Java\jdk-9.0.1" in my case

Cannot open output file, permission denied

I tried what @willll said, and it worked. I didint find exactly the .exe named after my project, but I did kill some weird looking tasks (after checking on the internet they were not critical), and it worked.

"Non-static method cannot be referenced from a static context" error

You need to correctly separate static data from instance data. In your code, onLoan and setLoanItem() are instance members. If you want to reference/call them you must do so via an instance. So you either want

public void loanItem() {
    this.media.setLoanItem("Yes");
}

or

public void loanItem(Media object) {
    object.setLoanItem("Yes");
}

depending on how you want to pass that instance around.

Attribute 'nowrap' is considered outdated. A newer construct is recommended. What is it?

Although there's CSS defines a text-wrap property, it's not supported by any major browser, but maybe vastly supported white-space property solves your problem.

Anonymous method in Invoke call

You need to create a delegate type. The keyword 'delegate' in the anonymous method creation is a bit misleading. You are not creating an anonymous delegate but an anonymous method. The method you created can be used in a delegate. Like this:

myControl.Invoke(new MethodInvoker(delegate() { (MyMethod(this, new MyEventArgs(someParameter)); }));

R cannot be resolved - Android error

If you work with eclipse: Sometimes eclipse supresses the error messages in the ressource files. Solution: Save a temporary ressource that has no errors in the layout folder. Build the project new. Then eclipse shows the correct error in the ressource file. Delete the temporary ressource.

Undefined symbols for architecture i386: _OBJC_CLASS_$_SKPSMTPMessage", referenced from: error

Yeah this is related to what allen said... look for TargetMembership in Utilities section of the source file. there is a checkbox that associates that file to a project. Checking this solved this issue for me too.

Duplicate AssemblyVersion Attribute

I found this answer on msdn, that explains marking the file as Content and then Copy to Output = If Newer. See article below:

https://social.msdn.microsoft.com/Forums/en-US/8671bdff-9b16-4b49-ba9e-227cc4df31b2/compile-error-cs0579-duplicate-assemblyversion-attribute?forum=vsgatk

GH

Maven compile: package does not exist

Not sure if there was file corruption or what, but after confirming proper pom configuration I was able to resolve this issue by deleting the jar from my local m2 repository, forcing Maven to download it again when I ran the tests.

intellij idea - Error: java: invalid source release 1.9

In Project Structure in Project SDK: modify SDK to 11 or higher and in Project language level: modify to 11 - Local variable syntax for lambda parameters

c++ compile error: ISO C++ forbids comparison between pointer and integer

You must remember to use single quotes for char constants. So use

if (answer == 'y') return true;

Rather than

if (answer == "y") return true;

I tested this and it works

Resolve build errors due to circular dependency amongst classes

You can avoid compilation errors if you remove the method definitions from the header files and let the classes contain only the method declarations and variable declarations/definitions. The method definitions should be placed in a .cpp file (just like a best practice guideline says).

The down side of the following solution is (assuming that you had placed the methods in the header file to inline them) that the methods are no longer inlined by the compiler and trying to use the inline keyword produces linker errors.

//A.h
#ifndef A_H
#define A_H
class B;
class A
{
    int _val;
    B* _b;
public:

    A(int val);
    void SetB(B *b);
    void Print();
};
#endif

//B.h
#ifndef B_H
#define B_H
class A;
class B
{
    double _val;
    A* _a;
public:

    B(double val);
    void SetA(A *a);
    void Print();
};
#endif

//A.cpp
#include "A.h"
#include "B.h"

#include <iostream>

using namespace std;

A::A(int val)
:_val(val)
{
}

void A::SetB(B *b)
{
    _b = b;
    cout<<"Inside SetB()"<<endl;
    _b->Print();
}

void A::Print()
{
    cout<<"Type:A val="<<_val<<endl;
}

//B.cpp
#include "B.h"
#include "A.h"
#include <iostream>

using namespace std;

B::B(double val)
:_val(val)
{
}

void B::SetA(A *a)
{
    _a = a;
    cout<<"Inside SetA()"<<endl;
    _a->Print();
}

void B::Print()
{
    cout<<"Type:B val="<<_val<<endl;
}

//main.cpp
#include "A.h"
#include "B.h"

int main(int argc, char* argv[])
{
    A a(10);
    B b(3.14);
    a.Print();
    a.SetB(&b);
    b.Print();
    b.SetA(&a);
    return 0;
}

Indentation Error in Python

It happened to me also, but I got the problem solved. I was using an indentation of 5 spaces, but when I pressed tab, it used to put a four space indent. So I think you should just use one thing; i.e. either tab button to add indent or spaces. And an ideal indentation is one of 4 spaces. I found IntelliJ to be very useful for these sort of things.

Call of overloaded function is ambiguous

Use

p.setval(static_cast<const char *>(0));

or

p.setval(static_cast<unsigned int>(0));

As indicated by the error, the type of 0 is int. This can just as easily be cast to an unsigned int or a const char *. By making the cast manually, you are telling the compiler which overload you want.

MySQL Update Inner Join tables query

For MySql WorkBench, Please use below :

update emp as a
inner join department b on a.department_id=b.id
set a.department_name=b.name
where a.emp_id in (10,11,12); 

What does "collect2: error: ld returned 1 exit status" mean?

Include: #include<stdlib.h>

and use System("cls") instead of clrscr()

NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle

In my case, this happen because of I deleted the Main.storyboard and in general tab Main Interface property cleared and added custom one as Start. After I Change the Main Interface to Start.storyboard except Start it's working.

Fatal error: "No Target Architecture" in Visual Studio

_WIN32 identifier is not defined.

use #include <SDKDDKVer.h>

MSVS generated projects wrap this include by generating a local "targetver.h"which is included by "stdafx.h" that is comiled into a precompiled-header through "stdafx.cpp".

EDIT : do you have a /D "WIN32" on your commandline ?

Assign a variable inside a Block to a variable outside a Block

yes block are the most used functionality , so in order to avoid the retain cycle we should avoid using the strong variable,including self inside the block, inspite use the _weak or weakself.

Cannot make a static reference to the non-static method

You can not make reference to static variable from non-static method. To understand this , you need to understand the difference between static and non-static.

Static variables are class variables , they belong to class with their only one instance , created at the first only. Non-static variables are initialized every time you create an object of the class.

Now coming to your question, when you use new() operator we will create copy of every non-static filed for every object, but it is not the case for static fields. That's why it gives compile time error if you are referencing a static variable from non-static method.

C compile error: Id returned 1 exit status

You may compiling your program while another program may be running in background. Firstly, see if another program is running .Close it and then try ro compile.

maven "cannot find symbol" message unhelpful

SOLUTION: @Before building your component (using mvn clean install). Build the entire project once and build your component again

WHY SO :
I get this error many times. Most of the times I will try to build my component alone (As I have not made changes elsewhere).

Right, But that extra jar which has been downloaded recently might have affected by changes done by a third party(inside their component). Making a full mvn clean install on entire project saved me many times

How to fix "namespace x already contains a definition for x" error? Happened after converting to VS2010

Me too got this error, When I change my WPF project's Target Framework to Framework Version 4.0 Client Profile -> Framework 4.0. It's solved by itself.

cc1plus: error: unrecognized command line option "-std=c++11" with g++

you should try this

g++-4.4 -std=c++0x or g++-4.7 -std=c++0x

Android java.exe finished with non-zero exit value 1

The answer for me was to free memory to the build process, closing programing or rebooting the machine (win10 seems to manage memory worse than win7)

Why did it fixed for me?

During the build, android studio doesn't find enough memory to compile but it doesnt show any error. The :app:preDexDebug error happened just when I tried to upload the compiled app to the phone.

Sometimes I could get through this point (no app:preDexDebug error), but when running the application on android I got "ClassNotFound" exceptions. This was the clue to discover android studio wasn't compiling all my files during build because of the lack of memory (win10 asked me to close android studio to save memory during the build), even though the IDE showing me that the build was successful.

Compile throws a "User-defined type not defined" error but does not go to the offending line of code

Had a similiar experience, but it was because I had renamed an enum in one of my classes. I exported and re-imported the Classes that had referred to the old enum and the error message disappeared. This suggests it is a caching issue in the VBA environment.

C compile error: "Variable-sized object may not be initialized"

You cannot do it. C compiler cannot do such a complex thing on stack.

You have to use heap and dynamic allocation.

What you really need to do:

  • compute size (nmsizeof(element)) of the memory you need
  • call malloc(size) to allocate the memory
  • create an accessor: int* access(ptr,x,y,rowSize) { return ptr + y*rowSize + x; }

Use *access(boardAux, x, y, size) = 42 to interact with the matrix.

How to compile .c file with OpenSSL includes?

For this gcc error, you should reference to to the gcc document about Search Path.

In short:

1) If you use angle brackets(<>) with #include, gcc will search header file firstly from system path such as /usr/local/include and /usr/include, etc.

2) The path specified by -Ldir command-line option, will be searched before the default directories.

3)If you use quotation("") with #include as #include "file", the directory containing the current file will be searched firstly.

so, the answer to your question is as following:

1) If you want to use header files in your source code folder, replace <> with "" in #include directive.

2) if you want to use -I command line option, add it to your compile command line.(if set CFLAGS in environment variables, It will not referenced automatically)

3) About package configuration(openssl.pc), I do not think it will be referenced without explicitly declared in build configuration.

How do I compile with -Xlint:unchecked?

I know it sounds weird, but I'm pretty sure this is your problem:

Somewhere in MyGui.java you're using a generic collection without specifying the type. For example if you're using an ArrayList somewhere, you are doing this:

List list = new ArrayList();

When you should be doing this:

List<String> list = new ArrayList<String>();

error::make_unique is not a member of ‘std’

If you have latest compiler, you can change the following in your build settings:

 C++ Language Dialect    C++14[-std=c++14]

This works for me.

Error in Swift class: Property not initialized at super.init call

Add nil to the end of the declaration.


// Must be nil or swift complains
var someProtocol:SomeProtocol? = nil

// Init the view
override init(frame: CGRect)
    super.init(frame: frame)
    ...

This worked for my case, but may not work for yours

Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug'

Use project root in terminal like this:-/Users/rajnish/Desktop/RankProjects/ProjectCloud

After that enter this command ./gradlew clean

It will work.

How do I concatenate multiple C++ strings on one line?

In 5 years nobody has mentioned .append?

#include <string>

std::string s;
s.append("Hello world, ");
s.append("nice to see you, ");
s.append("or not.");

Python3: ImportError: No module named '_ctypes' when using Value from module multiprocessing

This solved the same error for me on Debian:

sudo apt-get install libffi-dev

and compile again

Reference: issue31652

What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?

SOLVED

Using IntelliJ

Select Build->Rebuild Project will solve it

Operator overloading ==, !=, Equals

As Selman22 said, you are overriding the default object.Equals method, which accepts an object obj and not a safe compile time type.

In order for that to happen, make your type implement IEquatable<Box>:

public class Box : IEquatable<Box>
{
    double height, length, breadth;

    public static bool operator ==(Box obj1, Box obj2)
    {
        if (ReferenceEquals(obj1, obj2))
        {
            return true;
        }
        if (ReferenceEquals(obj1, null))
        {
            return false;
        }
        if (ReferenceEquals(obj2, null))
        {
            return false;
        }

        return obj1.Equals(obj2);
    }

    public static bool operator !=(Box obj1, Box obj2)
    {
        return !(obj1 == obj2);
    }

    public bool Equals(Box other)
    {
        if (ReferenceEquals(other, null))
        {
            return false;
        }
        if (ReferenceEquals(this, other))
        {
            return true;
        }

        return height.Equals(other.height) 
               && length.Equals(other.length) 
               && breadth.Equals(other.breadth);
    }

    public override bool Equals(object obj)
    {
        return Equals(obj as Box);
    }

    public override int GetHashCode()
    {
        unchecked
        {
            int hashCode = height.GetHashCode();
            hashCode = (hashCode * 397) ^ length.GetHashCode();
            hashCode = (hashCode * 397) ^ breadth.GetHashCode();
            return hashCode;
        }
    }
}

Another thing to note is that you are making a floating point comparison using the equality operator and you might experience a loss of precision.

Identifier not found error on function call

At the time the compiler encounters the call to swapCase in main(), it does not know about the function swapCase, so it reports an error. You can either move the definition of swapCase above main, or declare swap case above main:

void swapCase(char* name);

Also, the 32 in swapCase causes the reader to pause and wonder. The comment helps! In this context, it would add clarity to write

if ('A' <= name[i] && name[i] <= 'Z')
    name[i] += 'a' - 'A';
else if ('a' <= name[i] && name[i] <= 'z')
    name[i] += 'A' - 'a';

The construction in my if-tests is a matter of personal style. Yours were just fine. The main thing is the way to modify name[i] -- using the difference in 'a' vs. 'A' makes it more obvious what is going on, and nobody has to wonder if the '32' is actually correct.

Good luck learning!

Unexpected end of file error

If you do not use precompiled headers in your project, set the Create/Use Precompiled Header property of source files to Not Using Precompiled Headers. To set this compiler option, follow these steps:

  • In the Solution Explorer pane of the project, right-click the project name, and then click Properties.
  • In the left pane, click the C/C++ folder.
  • Click the Precompiled Headers node.
  • In the right pane, click Create/Use Precompiled Header, and then click Not Using Precompiled Headers.

Compiler error: "initializer element is not a compile-time constant"

When you define a variable outside the scope of a function, that variable's value is actually written into your executable file. This means you can only use a constant value. Since you don't know everything about the runtime environment at compile time (which classes are available, what is their structure, etc.), you cannot create objective c objects until runtime, with the exception of constant strings, which are given a specific structure and guaranteed to stay that way. What you should do is initialize the variable to nil and use +initialize to create your image. initialize is a class method which will be called before any other method is called on your class.

Example:

NSImage *imageSegment = nil;
+ (void)initialize {
    if(!imageSegment)
        imageSegment = [[NSImage alloc] initWithContentsOfFile:@"/User/asd.jpg"];
}
- (id)init {
    self = [super init];
    if (self) {
        // Initialization code here.
    }

    return self;
}

error C2220: warning treated as error - no 'object' file generated

This warning is about unsafe use of strcpy. Try IOBname[ii]='\0'; instead.

Compiler error: "class, interface, or enum expected"

class, interface, or enum expected

The above error is even possible when import statement is miss spelled. A proper statement is "import com.company.HelloWorld;"

If by mistake while code writing/editing it is miss written like "t com.company.HelloWorld;"

compiler will show "class, interface, or enum expected"

X11/Xlib.h not found in Ubuntu

Andrew White's answer is sufficient to get you moving. Here's a step-by-step for beginners.

A simple get started:

Create test.cpp: (This will be built and run to verify you got things set up right.)

#include <X11/Xlib.h>
#include <unistd.h>


main()
{
  // Open a display.
  Display *d = XOpenDisplay(0);

  if ( d )
    {
      // Create the window
      Window w = XCreateWindow(d, DefaultRootWindow(d), 0, 0, 200,
                   100, 0, CopyFromParent, CopyFromParent,
                   CopyFromParent, 0, 0);

      // Show the window
      XMapWindow(d, w);
      XFlush(d);

      // Sleep long enough to see the window.
      sleep(10);
    }
  return 0;
}

(Source: LinuxGazette)

Try: g++ test.cpp -lX11 If it builds to a.out, try running it. If you see a simple window drawn, you have the necessary libraries, and some other root problem is afoot.

If your response is:

    test.cpp:1:22: fatal error: X11/Xlib.h: No such file or directory
    compilation terminated.

you need to install X11 development libraries. sudo apt-get install libx11-dev

Retry g++ test.cpp -lX11

If it works, you're golden.

Tested using a fresh install of libX11-dev_2%3a1.5.0-1_i386.deb

Error: Could not find or load main class in intelliJ IDE

I ran into this problem when my Java class was under src/main/kotlin. After I moved it to src/main/java, the problem was gone.

System not declared in scope?

You need to add:

 #include <cstdlib>

in order for the compiler to see the prototype for system().

How do I prompt for Yes/No/Cancel input in a Linux shell script?

Most of the times in such scenarios, you need to continue executing the script till the user keeps on entering "yes" and only need to stop when user enters "no". The below snippet would help you achieve this!

#!/bin/bash
input="yes"
while [ "$input" == "yes" ]
do
  echo "execute script functionality here..!!"
  echo "Do you want to continue (yes/no)?"
  read input
done

Byte[] to ASCII

Encoding.GetString Method (Byte[]) convert bytes to a string.

When overridden in a derived class, decodes all the bytes in the specified byte array into a string.

Namespace: System.Text
Assembly: mscorlib (in mscorlib.dll)

Syntax

public virtual string GetString(byte[] bytes)

Parameters

bytes
    Type: System.Byte[]
    The byte array containing the sequence of bytes to decode.

Return Value

Type: System.String
A String containing the results of decoding the specified sequence of bytes.

Exceptions

ArgumentException        - The byte array contains invalid Unicode code points.
ArgumentNullException    - bytes is null.
DecoderFallbackException - A fallback occurred (see Character Encoding in the .NET Framework for complete explanation) or DecoderFallback is set to DecoderExceptionFallback.

Remarks

If the data to be converted is available only in sequential blocks (such as data read from a stream) or if the amount of data is so large that it needs to be divided into smaller blocks, the application should use the Decoder or the Encoder provided by the GetDecoder method or the GetEncoder method, respectively, of a derived class.

See the Remarks under Encoding.GetChars for more discussion of decoding techniques and considerations.

filename.whl is not supported wheel on this platform

For me, it worked when I selected the correct bit of my Python version, NOT the one of my computer version.

Mine is 32bit, and my computer is 64bit. That was the problem and the 32bit version of fixed it.

To be exact, here is the one that I downloaded and worked for me:

mysqlclient-1.3.13-cp37-cp37m-win32.whl

Once again, just make sure to chose your python version of bits and not your system one.

How does DISTINCT work when using JPA and Hibernate

You are close.

select DISTINCT(c.name) from Customer c

How to extend / inherit components?

Components can be extended as same as a typescript class inheritance, just that you have to override the selector with a new name. All Input() and Output() Properties from the Parent Component works as normal

Update

@Component is a decorator,

Decorators are applied during the declaration of class not on objects.

Basically, decorators add some metadata to the class object and that cannot be accessed via inheritance.

If you want to achieve the Decorator Inheritance I would Suggest writing a custom decorator. Something like below example.

export function CustomComponent(annotation: any) {
    return function (target: Function) {
    var parentTarget = Object.getPrototypeOf(target.prototype).constructor;

    var parentAnnotations = Reflect.getMetadata('annotations', parentTarget);
    var parentParamTypes = Reflect.getMetadata('design:paramtypes', parentTarget);
    var parentPropMetadata = Reflect.getMetadata('propMetadata', parentTarget);
    var parentParameters = Reflect.getMetadata('parameters', parentTarget);

    var parentAnnotation = parentAnnotations[0];

    Object.keys(parentAnnotation).forEach(key => {
    if (isPresent(parentAnnotation[key])) {
        if (!isPresent(annotation[key])) {
        annotation[key] = parentAnnotation[key];
        }
    }
    });
    // Same for the other metadata
    var metadata = new ComponentMetadata(annotation);

    Reflect.defineMetadata('annotations', [ metadata ], target);
    };
};

Refer: https://medium.com/@ttemplier/angular2-decorators-and-class-inheritance-905921dbd1b7

Regular Expression for any number greater than 0?

The simple answer is: ^[1-9][0-9]*$

How to save final model using keras?

You can use model.save(filepath) to save a Keras model into a single HDF5 file which will contain:

  • the architecture of the model, allowing to re-create the model.
  • the weights of the model.
  • the training configuration (loss, optimizer)
  • the state of the optimizer, allowing to resume training exactly where you left off.

In your Python code probable the last line should be:

model.save("m.hdf5")

This allows you to save the entirety of the state of a model in a single file. Saved models can be reinstantiated via keras.models.load_model().

The model returned by load_model() is a compiled model ready to be used (unless the saved model was never compiled in the first place).

model.save() arguments:

  • filepath: String, path to the file to save the weights to.
  • overwrite: Whether to silently overwrite any existing file at the target location, or provide the user with a manual prompt.
  • include_optimizer: If True, save optimizer's state together.

Very Long If Statement in Python

According to PEP8, long lines should be placed in parentheses. When using parentheses, the lines can be broken up without using backslashes. You should also try to put the line break after boolean operators.

Further to this, if you're using a code style check such as pycodestyle, the next logical line needs to have different indentation to your code block.

For example:

if (abcdefghijklmnopqrstuvwxyz > some_other_long_identifier and
        here_is_another_long_identifier != and_finally_another_long_name):
    # ... your code here ...
    pass

How to set a Header field on POST a form?

From FormData documention:

XMLHttpRequest Level 2 adds support for the new FormData interface. FormData objects provide a way to easily construct a set of key/value pairs representing form fields and their values, which can then be easily sent using the XMLHttpRequest send() method.

With an XMLHttpRequest you can set the custom headers and then do the POST.

how to use JSON.stringify and json_decode() properly

When you save some data using JSON.stringify() and then need to read that in php. The following code worked for me.

json_decode( html_entity_decode( stripslashes ($jsonString ) ) );

Thanks to @Thisguyhastwothumbs

Bash or KornShell (ksh)?

For one thing, bash has tab completion. This alone is enough to make me prefer it over ksh.

Z shell has a good combination of ksh's unique features with the nice things that bash provides, plus a lot more stuff on top of that.

How can I get a character in a string by index?

string s = "hello";
char c = s[1];
// now c == 'e'

See also Substring, to return more than one character.

What is path of JDK on Mac ?

On my Mac:

/System/Library/Frameworks/JavaVM.framework/Home/

btw, did you tried which java?

Process.start: how to get the output?

How to launch a process (such as a bat file, perl script, console program) and have its standard output displayed on a windows form:

processCaller = new ProcessCaller(this);
//processCaller.FileName = @"..\..\hello.bat";
processCaller.FileName = @"commandline.exe";
processCaller.Arguments = "";
processCaller.StdErrReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.StdOutReceived += new DataReceivedHandler(writeStreamInfo);
processCaller.Completed += new EventHandler(processCompletedOrCanceled);
processCaller.Cancelled += new EventHandler(processCompletedOrCanceled);
// processCaller.Failed += no event handler for this one, yet.

this.richTextBox1.Text = "Started function.  Please stand by.." + Environment.NewLine;

// the following function starts a process and returns immediately,
// thus allowing the form to stay responsive.
processCaller.Start();    

You can find ProcessCaller on this link: Launching a process and displaying its standard output

Can't Autowire @Repository annotated interface in Spring Boot

There is another cause for this type of problem what I would like to share, because I struggle in this problem for some time and I could't find any answer on SO.

In a repository like:

@Repository
public interface UserEntityDao extends CrudRepository<UserEntity, Long>{

}

If your entity UserEntity does not have the @Entity annotation on the class, you will have the same error.

This error is confusing for this case, because you focus on trying to resolve the problem about Spring not found the Repository but the problem is the entity. And if you came to this answer trying to test your Repository, this answer may help you.

.gitignore and "The following untracked working tree files would be overwritten by checkout"

This happened to me on a Windows 8 system, using Git from the command prompt. The rest of my team uses TFS, and I use Microsoft's git-tf to push/pull between TFS and my local Git repository.

The problem arose due to some files that had been renamed only to change their case. What appears to have happened was this:

  • The files were checked in with mixed casing in their names.
  • In a later commit, the file names were changed to all lower-case.
  • git-tf initially got the files in mixed case.
  • When the files were renamed to lower-case, git-tf didn't get the files because to Windows 8 those file names are equivalent.
  • Since Git is case-sensitive, it complained that I had the mixed-case files that weren't in source control. But using git status, I couldn't see any changes, since in the Windows command prompt those file names are equivalent.

The simplest solution for me was:

  • git checkout a previous version of the project, well before those files were ever added.
  • Then git checkout the latest version of the project, with the correct file casing.

How can I create a copy of an object in Python?

Shallow copy with copy.copy()

#!/usr/bin/env python3

import copy

class C():
    def __init__(self):
        self.x = [1]
        self.y = [2]

# It copies.
c = C()
d = copy.copy(c)
d.x = [3]
assert c.x == [1]
assert d.x == [3]

# It's shallow.
c = C()
d = copy.copy(c)
d.x[0] = 3
assert c.x == [3]
assert d.x == [3]

Deep copy with copy.deepcopy()

#!/usr/bin/env python3
import copy
class C():
    def __init__(self):
        self.x = [1]
        self.y = [2]
c = C()
d = copy.deepcopy(c)
d.x[0] = 3
assert c.x == [1]
assert d.x == [3]

Documentation: https://docs.python.org/3/library/copy.html

Tested on Python 3.6.5.

Picking a random element from a set

A somewhat related Did You Know:

There are useful methods in java.util.Collections for shuffling whole collections: Collections.shuffle(List<?>) and Collections.shuffle(List<?> list, Random rnd).

axios post request to send form data

https://www.npmjs.com/package/axios

Its Working

// "content-type": "application/x-www-form-urlencoded", // commit this

import axios from 'axios';

let requestData = {
      username : "[email protected]",
      password: "123456
    };
   
    const url = "Your Url Paste Here";

    let options = {
      method: "POST",
      headers: { 
        'Content-type': 'application/json; charset=UTF-8',

        Authorization: 'Bearer ' + "your token Paste Here",
      },
      data: JSON.stringify(requestData),
      url
    };
    axios(options)
      .then(response => {
        console.log("K_____ res :- ", response);
        console.log("K_____ res status:- ", response.status);
      })
      .catch(error => {
        console.log("K_____ error :- ", error);
      });

fetch request

fetch(url, {
    method: 'POST',
    body: JSON.stringify(requestPayload),           
    headers: {
        'Content-type': 'application/json; charset=UTF-8',
        Authorization: 'Bearer ' + token,
    },
})
    // .then((response) => response.json()) .  // commit out this part if response body is empty
    .then((json) => {
        console.log("response :- ", json);
    }).catch((error)=>{
        console.log("Api call error ", error.message);
        alert(error.message);
});

Flutter: Setting the height of the AppBar

At the time of writing this, I was not aware of PreferredSize. Cinn's answer is better to achieve this.

You can create your own custom widget with a custom height:

import "package:flutter/material.dart";

class Page extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Column(children : <Widget>[new CustomAppBar("Custom App Bar"), new Container()],);
  }
}


class CustomAppBar extends StatelessWidget {

  final String title;
  final double barHeight = 50.0; // change this for different heights 

  CustomAppBar(this.title);

  @override
  Widget build(BuildContext context) {
    final double statusbarHeight = MediaQuery
        .of(context)
        .padding
        .top;

    return new Container(
      padding: new EdgeInsets.only(top: statusbarHeight),
      height: statusbarHeight + barHeight,
      child: new Center(
        child: new Text(
          title,
          style: new TextStyle(fontSize: 20.0, fontWeight: FontWeight.bold),
        ),
      ),
    );
  }
}

Running interactive commands in Paramiko

Take a look at example and do in similar way

(sorce from http://jessenoller.com/2009/02/05/ssh-programming-with-paramiko-completely-different/):

    ssh.connect('127.0.0.1', username='jesse', 
        password='lol')
    stdin, stdout, stderr = ssh.exec_command(
        "sudo dmesg")
    stdin.write('lol\n')
    stdin.flush()
    data = stdout.read.splitlines()
    for line in data:
        if line.split(':')[0] == 'AirPort':
            print line

Removing items from a ListBox in VB.net

There is a simple method for deleting selected items, and all these people are going for a hard method:

lstYOURVARIABLE.Items.Remove(lstYOURVARIABLE.SelectedItem)

I used this in Visual Basic mode on Visual Studio.

How to pass a callback as a parameter into another function

Yup. Function references are just like any other object reference, you can pass them around to your heart's content.

Here's a more concrete example:

_x000D_
_x000D_
function foo() {
    console.log("Hello from foo!");
}

function caller(f) {
    // Call the given function
    f();
}

function indirectCaller(f) {
    // Call `caller`, who will in turn call `f`
    caller(f);
}

// Do it
indirectCaller(foo); // logs "Hello from foo!"
_x000D_
_x000D_
_x000D_

You can also pass in arguments for foo:

_x000D_
_x000D_
function foo(a, b) {
    console.log(a + " + " + b + " = " + (a + b));
}

function caller(f, v1, v2) {
    // Call the given function
    f(v1, v2);
}

function indirectCaller(f, v1, v2) {
    // Call `caller`, who will in turn call `f`
    caller(f, v1, v2);
}

// Do it
indirectCaller(foo, 1, 2); // logs "1 + 2 = 3"
_x000D_
_x000D_
_x000D_

How to pretty-print a numpy.array without scientific notation and with given precision?

I often want different columns to have different formats. Here is how I print a simple 2D array using some variety in the formatting by converting (slices of) my NumPy array to a tuple:

import numpy as np
dat = np.random.random((10,11))*100  # Array of random values between 0 and 100
print(dat)                           # Lines get truncated and are hard to read
for i in range(10):
    print((4*"%6.2f"+7*"%9.4f") % tuple(dat[i,:]))

How to force child div to be 100% of parent div's height without specifying parent's height?

#main {
   display: table;
} 
#navigation, #content {
   display: table-cell;
}

Look at this example.

How to get current url in view in asp.net core 1.0

You can consider to use this extension method (from Microsoft.AspNetCore.Http.Extensions namespace:

@Context.Request.GetDisplayUrl()

For some my projects i prefer more flexible solution. There are two extensions methods.

1) First method creates Uri object from incoming request data (with some variants through optional parameters). 2) Second method receives Uri object and returns string in following format (with no trailing slash): Scheme_Host_Port

public static Uri GetUri(this HttpRequest request, bool addPath = true, bool addQuery = true)
    {
        var uriBuilder = new UriBuilder
        {
            Scheme = request.Scheme,
            Host = request.Host.Host,
            Port = request.Host.Port.GetValueOrDefault(80),
            Path = addPath ? request.Path.ToString() : default(string),
            Query = addQuery ? request.QueryString.ToString() : default(string)
        };
        return uriBuilder.Uri;
    }

    public static string HostWithNoSlash(this Uri uri)
    {
        return uri.GetComponents(UriComponents.SchemeAndServer, UriFormat.UriEscaped);
    }

Usage:

//before >> https://localhost:44304/information/about?param1=a&param2=b
        Request.GetUri(addQuery: false);
        //after >> https://localhost:44304/information/about

        //before >> https://localhost:44304/information/about?param1=a&param2=b
        new Uri("https://localhost:44304/information/about?param1=a&param2=b").GetHostWithNoSlash();
        //after >> https://localhost:44304

How to show uncommitted changes in Git and some Git diffs in detail

I had a situation of git status showing changes, but git diff printing nothing, although there were changes in several lines. However:

$ git diff data.txt > myfile
$ cat myfile
<prints diff>

Git 2.20.1 on raspbian. Other commands like git checkout, git pull are printing to stdout without problems.

Convert a numpy.ndarray to string(or bytes) and convert it back to numpy.ndarray

I know, I am late but here is the correct way of doing it. using base64. This technique will convert the array to string.

import base64
import numpy as np
random_array = np.random.randn(32,32)
string_repr = base64.binascii.b2a_base64(random_array).decode("ascii")
array = np.frombuffer(base64.binascii.a2b_base64(string_repr.encode("ascii"))) 

For array to string

Convert binary data to a line of ASCII characters in base64 coding and decode to ASCII to get string repr.

For string to array

First, encode the string in ASCII format then Convert a block of base64 data back to binary and return the binary data.

How to access random item in list?

Why not:

public static T GetRandom<T>(this IEnumerable<T> list)
{
   return list.ElementAt(new Random(DateTime.Now.Millisecond).Next(list.Count()));
}

Why does an SSH remote command get fewer environment variables then when run manually?

Shell environment does not load when running remote ssh command. You can edit ssh environment file:

vi ~/.ssh/environment

Its format is:

VAR1=VALUE1
VAR2=VALUE2

Also, check sshd configuration for PermitUserEnvironment=yes option.

How do I get formatted JSON in .NET using C#?

netcoreapp3.1

var js = JsonSerializer.Serialize(obj, new JsonSerializerOptions {
             WriteIndented = true
         });

Collections.sort with multiple fields

Do you see anything wrong with the code?

Yes. Why are you adding the three fields together before you compare them?

I would probably do something like this: (assuming the fields are in the order you wish to sort them in)

@Override public int compare(final Report record1, final Report record2) {
    int c;
    c = record1.getReportKey().compareTo(record2.getReportKey());
    if (c == 0)
       c = record1.getStudentNumber().compareTo(record2.getStudentNumber());
    if (c == 0)
       c = record1.getSchool().compareTo(record2.getSchool());
    return c;
}

How do I make a dictionary with multiple keys to one value?

Your example creates multiple key: value pairs if using fromkeys. If you don't want this, you can use one key and create an alias for the key. For example if you are using a register map, your key can be the register address and the alias can be register name. That way you can perform read/write operations on the correct register.

>>> mydict = {}
>>> mydict[(1,2)] = [30, 20]
>>> alias1 = (1,2)
>>> print mydict[alias1]
[30, 20]
>>> mydict[(1,3)] = [30, 30]
>>> print mydict
{(1, 2): [30, 20], (1, 3): [30, 30]}
>>> alias1 in mydict
True

Can Flask have optional URL parameters?

I know this post is really old but I worked on a package that does this called flask_optional_routes. The code is located at: https://github.com/sudouser2010/flask_optional_routes.

from flask import Flask

from flask_optional_routes import OptionalRoutes


app = Flask(__name__)
optional = OptionalRoutes(app)

@optional.routes('/<user_id>/<user_name>?/')
def foobar(user_id, user_name=None):
    return 'it worked!'

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=5000)

How to create timer events using C++ 11?

Made a simple implementation of what I believe to be what you want to achieve. You can use the class later with the following arguments:

  • int (milliseconds to wait until to run the code)
  • bool (if true it returns instantly and runs the code after specified time on another thread)
  • variable arguments (exactly what you'd feed to std::bind)

You can change std::chrono::milliseconds to std::chrono::nanoseconds or microseconds for even higher precision and add a second int and a for loop to specify for how many times to run the code.

Here you go, enjoy:

#include <functional>
#include <chrono>
#include <future>
#include <cstdio>

class later
{
public:
    template <class callable, class... arguments>
    later(int after, bool async, callable&& f, arguments&&... args)
    {
        std::function<typename std::result_of<callable(arguments...)>::type()> task(std::bind(std::forward<callable>(f), std::forward<arguments>(args)...));

        if (async)
        {
            std::thread([after, task]() {
                std::this_thread::sleep_for(std::chrono::milliseconds(after));
                task();
            }).detach();
        }
        else
        {
            std::this_thread::sleep_for(std::chrono::milliseconds(after));
            task();
        }
    }

};

void test1(void)
{
    return;
}

void test2(int a)
{
    printf("%i\n", a);
    return;
}

int main()
{
    later later_test1(1000, false, &test1);
    later later_test2(1000, false, &test2, 101);

    return 0;
}

Outputs after two seconds:

101

Android WSDL/SOAP service client

I have just completed a android App about wsdl,i have some tips to append:

1.the most important resource is www.wsdl2code.com

2.you can take you username and password with header, which encoded with Base64,such as :

        String USERNAME = "yourUsername";
    String PASSWORD = "yourPassWord";
    StringBuffer auth = new StringBuffer(USERNAME);
    auth.append(':').append(PASSWORD);
    byte[] raw = auth.toString().getBytes();
    auth.setLength(0);
    auth.append("Basic ");
    org.kobjects.base64.Base64.encode(raw, 0, raw.length, auth);
    List<HeaderProperty> headers = new ArrayList<HeaderProperty>();
    headers.add(new HeaderProperty("Authorization", auth.toString())); // "Basic V1M6"));

    Vectordianzhan response = bydWs.getDianzhans(headers);

3.somethimes,you are not sure either ANDROID code or webserver is wrong, then debug is important.in the sample , catching "XmlPullParserException" ,log "requestDump" and "responseDump"in the exception.additionally, you should catch the IP package with adb.

    try {
    Logg.i(TAG, "2  ");
    Object response = androidHttpTransport.call(SOAP_ACTION, envelope, headers); 
    Logg.i(TAG, "requestDump: " + androidHttpTransport.requestDump);
    Logg.i(TAG, "responseDump: "+ androidHttpTransport.responseDump);
    Logg.i(TAG, "3");
} catch (IOException e) {
    Logg.i(TAG, "IOException");
} 
catch (XmlPullParserException e) {
     Logg.i(TAG, "requestDump: " + androidHttpTransport.requestDump);
     Logg.i(TAG, "responseDump: "+ androidHttpTransport.responseDump);
     Logg.i(TAG, "XmlPullParserException");
     e.printStackTrace();
}

How to setup Tomcat server in Netbeans?

While installing Netbeans itself, you will get an option which servers needs to be installed and integrated with Netbeans. First screen itself will show.

Another option is to reinstall Netbeans by closing all the open projects.

Pure CSS to make font-size responsive based on dynamic amount of characters

Create a lookup table that computes font-size based on the length of the string inside your <div>.

const fontSizeLookupTable = () => {
  // lookup table looks like: [ '72px', ..., '32px', ..., '16px', ..., ]
  let a = [];
  // adjust this based on how many characters you expect in your <div>
  a.length = 32;
  // adjust the following ranges empirically
  a.fill( '72px' ,     );
  a.fill( '32px' , 4 , );
  a.fill( '16px' , 8 , );
  // add more ranges as necessary
  return a;
}

const computeFontSize = stringLength => {
  const table = fontSizeLookupTable();
  return stringLength < table.length ? table[stringLength] : '16px';
}

Adjust and tune all parameters by empirical test.

Removing nan values from an array

This is my approach to filter ndarray "X" for NaNs and infs,

I create a map of rows without any NaN and any inf as follows:

idx = np.where((np.isnan(X)==False) & (np.isinf(X)==False))

idx is a tuple. It's second column (idx[1]) contains the indices of the array, where no NaN nor inf where found across the row.

Then:

filtered_X = X[idx[1]]

filtered_X contains X without NaN nor inf.

In practice, what are the main uses for the new "yield from" syntax in Python 3.3?

yield from basically chains iterators in a efficient way:

# chain from itertools:
def chain(*iters):
    for it in iters:
        for item in it:
            yield item

# with the new keyword
def chain(*iters):
    for it in iters:
        yield from it

As you can see it removes one pure Python loop. That's pretty much all it does, but chaining iterators is a pretty common pattern in Python.

Threads are basically a feature that allow you to jump out of functions at completely random points and jump back into the state of another function. The thread supervisor does this very often, so the program appears to run all these functions at the same time. The problem is that the points are random, so you need to use locking to prevent the supervisor from stopping the function at a problematic point.

Generators are pretty similar to threads in this sense: They allow you to specify specific points (whenever they yield) where you can jump in and out. When used this way, generators are called coroutines.

Read this excellent tutorials about coroutines in Python for more details

Convert varchar to uniqueidentifier in SQL Server

your varchar col C:

SELECT CONVERT(uniqueidentifier,LEFT(C, 8)
                                + '-' +RIGHT(LEFT(C, 12), 4)
                                + '-' +RIGHT(LEFT(C, 16), 4)
                                + '-' +RIGHT(LEFT(C, 20), 4)
                                + '-' +RIGHT(C, 12))

PG::ConnectionBad - could not connect to server: Connection refused

My problem was in my application.yml file. My database url on heroku was not using port 5342. Check your heroku config var DATABASE_URL. Make sure that matches exactly with was in your application.yml for the applicable database.

How to check whether an array is empty using PHP?

In my opinion the simplest way for an indexed array would be simply:

    if ($array) {
      //Array is not empty...  
    }

An 'if' condition on the array would evaluate to true if the array is not empty and false if the array is empty. This is not applicable to associative arrays.

How to resize Twitter Bootstrap modal dynamically based on the content

Since your content must be dynamic you can set the css properties of the modal dynamically on show event of the modal which will re-size the modal overriding its default specs. Reason being bootstrap applies a max-height to the modal body with the css rule as below:

.modal-body {
    position: relative;
    overflow-y: auto;
    max-height: 400px;
    padding: 15px;
}

So you can add inline styles dynamically using jquery css method:

For newer versions of bootstrap use show.bs.modal

$('#modal').on('show.bs.modal', function () {
       $(this).find('.modal-body').css({
              width:'auto', //probably not needed
              height:'auto', //probably not needed 
              'max-height':'100%'
       });
});

For older versions of bootstrap use show

$('#modal').on('show', function () {
       $(this).find('.modal-body').css({
              width:'auto', //probably not needed
              height:'auto', //probably not needed 
              'max-height':'100%'
       });
});

or use a css rule to override:

.autoModal.modal .modal-body{
    max-height: 100%;
}

and add this class autoModal to your target modals.

Change the content dynamically in the fiddle, you will see the modal getting resized accordingly. Demo

Newer version of bootstrap see the available event names.

  • show.bs.modal This event fires immediately when the show instance method is called. If caused by a click, the clicked element is available as the relatedTarget property of the event.
  • shown.bs.modal This event is fired when the modal has been made visible to the user (will wait for CSS transitions to complete). If caused by a click, the clicked element is available as the relatedTarget property of the event.
  • hide.bs.modal This event is fired immediately when the hide instance method has been called.
  • hidden.bs.modal This event is fired when the modal has finished being hidden from the user (will wait for CSS transitions to complete).
  • loaded.bs.modal This event is fired when the modal has loaded content using the remote option.

Older version of bootstrap modal events supported.

  • Show - This event fires immediately when the show instance method is called.
  • shown - This event is fired when the modal has been made visible to the user (will wait for css transitions to complete).
  • hide - This event is fired immediately when the hide instance method has been called.
  • hidden - This event is fired when the modal has finished being hidden from the user (will wait for css transitions to complete).

How to copy a directory structure but only include certain files (using windows batch files)

try piping output of find (ie. the file path) into cpio

find . -type f -name '*.jpg' | cpio -p -d -v targetdir/

cpio checks timestamp on target files -- so its safe and fast.

remove -v for faster op, once you get used to it.

Download file from an ASP.NET Web API method using AngularJS

I have gone through array of solutions and this is what I found to have worked great for me.

In my case I needed to send a post request with some credentials. Small overhead was to add jquery inside the script. But was worth it.

var printPDF = function () {
        //prevent double sending
        var sendz = {};
        sendz.action = "Print";
        sendz.url = "api/Print";
        jQuery('<form action="' + sendz.url + '" method="POST">' +
            '<input type="hidden" name="action" value="Print" />'+
            '<input type="hidden" name="userID" value="'+$scope.user.userID+'" />'+
            '<input type="hidden" name="ApiKey" value="' + $scope.user.ApiKey+'" />'+
            '</form>').appendTo('body').submit().remove();

    }

Split array into chunks

EDIT: @mblase75 added more concise code to the earlier answer while I was writing mine, so I recommend going with his solution.

You could use code like this:

var longArray = ["Element 1","Element 2","Element 3", /*...*/];
var smallerArrays = []; // will contain the sub-arrays of 10 elements each
var arraySize = 10;
for (var i=0;i<Math.ceil(longArray.length/arraySize);i++) {
    smallerArrays.push(longArray.slice(i*arraySize,i*arraySize+arraySize));
}

Change the value of arraySize to change the maximum length of the smaller arrays.

IsNullOrEmpty with Object

I found that DataGridViewTextBox values and some JSON objects don't equal Null but instead are "{}" values. Comparing them to Null doesn't work but using these do the trick:

if (cell.Value is System.DBNull)

if (cell.Value == System.DBNull.Value)

A good excerpt I found concerning the difference between Null and DBNull:

Do not confuse the notion of null in an object-oriented programming language with a DBNull object. In an object-oriented programming language, null means the absence of a reference to an object. DBNull represents an uninitialized variant or nonexistent database column.

You can learn more about the DBNull class here.

How to put a component inside another component in Angular2?

I think in your Angular-2 version directives are not supported in Component decorator, hence you have to register directive same as other component in @NgModule and then import in component as below and also remove directives: [ChildComponent] from decorator.

import {myDirective} from './myDirective';

Get the name of a pandas DataFrame

You can name the dataframe with the following, and then call the name wherever you like:

import pandas as pd
df = pd.DataFrame( data=np.ones([4,4]) )
df.name = 'Ones'

print df.name
>>>
Ones

Hope that helps.

How to move child element from one parent to another using jQuery

$('#parent2').prepend($('#table1_length')).prepend($('#table1_filter'));

doesn't work for you? I think it should...

Source file not compiled Dev C++

You can always try doing it manually from the command prompt. Navigate to the path of the file and type:

gcc filename.c -o filename

Android Studio: “Execution failed for task ':app:mergeDebugResources'” if project is created on drive C:

Remove any capital letters or other not allowed symbols in resource file name.

Example: activity_parkingList --> activity_parking_list

What is the difference between i++ & ++i in a for loop?

They both increment the number. ++i is equivalent to i = i + 1.

i++ and ++i are very similar but not exactly the same. Both increment the number, but ++i increments the number before the current expression is evaluted, whereas i++ increments the number after the expression is evaluated.

int i = 3;
int a = i++; // a = 3, i = 4
int b = ++a; // b = 4, a = 4

How to make a .NET Windows Service start right after the installation?

Use the .NET ServiceController class to start it, or issue the commandline command to start it --- "net start servicename". Either way works.

How can I kill whatever process is using port 8080 so that I can vagrant up?

sudo lsof -i:8080

By running the above command you can see what are all the jobs running.

kill -9 <PID Number>

Enter the PID (process identification number), so this will terminate/kill the instance.

Accessing SQL Database in Excel-VBA

@firedrawndagger: to list field names/column headers iterate through the recordset Fields collection and insert the name:

Dim myRS as ADODB.Recordset
Dim fld as Field
Dim strFieldName as String 

For Each fld in myRS.Fields
    Activesheet.Selection = fld.Name
    [Some code that moves to next column]
Next

Sending a file over TCP sockets in Python

You can send some flag to stop while loop in server

for example

Server side:

import socket
s = socket.socket()
s.bind(("localhost", 5000))
s.listen(1)
c,a = s.accept()
filetodown = open("img.png", "wb")
while True:
   print("Receiving....")
   data = c.recv(1024)
   if data == b"DONE":
           print("Done Receiving.")
           break
   filetodown.write(data)
filetodown.close()
c.send("Thank you for connecting.")
c.shutdown(2)
c.close()
s.close()
#Done :)

Client side:

import socket
s = socket.socket()
s.connect(("localhost", 5000))
filetosend = open("img.png", "rb")
data = filetosend.read(1024)
while data:
    print("Sending...")
    s.send(data)
    data = filetosend.read(1024)
filetosend.close()
s.send(b"DONE")
print("Done Sending.")
print(s.recv(1024))
s.shutdown(2)
s.close()
#Done :)

PHP Fatal error: Class 'PDO' not found

I had the same problem on GoDaddy. I added the extension=pdo.so to php.ini, still didn't work. And then only one thing came to my mind: Permissions

Before uploading the file, kill all PHP processes(cPanel->PHP Processes).

The problem was that with the file permissions, it was set to 0644 and was not executable . You need to set the file permission at least 0755.

Permissions

Given a starting and ending indices, how can I copy part of a string in C?

Use strncpy

e.g.

strncpy(dest, src + beginIndex, endIndex - beginIndex);

This assumes you've

  1. Validated that dest is large enough.
  2. endIndex is greater than beginIndex
  3. beginIndex is less than strlen(src)
  4. endIndex is less than strlen(src)

Fitting a histogram with python

Here is an example that uses scipy.optimize to fit a non-linear functions like a Gaussian, even when the data is in a histogram that isn't well ranged, so that a simple mean estimate would fail. An offset constant also would cause simple normal statistics to fail ( just remove p[3] and c[3] for plain gaussian data).

from pylab import *
from numpy import loadtxt
from scipy.optimize import leastsq

fitfunc  = lambda p, x: p[0]*exp(-0.5*((x-p[1])/p[2])**2)+p[3]
errfunc  = lambda p, x, y: (y - fitfunc(p, x))

filename = "gaussdata.csv"
data     = loadtxt(filename,skiprows=1,delimiter=',')
xdata    = data[:,0]
ydata    = data[:,1]

init  = [1.0, 0.5, 0.5, 0.5]

out   = leastsq( errfunc, init, args=(xdata, ydata))
c = out[0]

print "A exp[-0.5((x-mu)/sigma)^2] + k "
print "Parent Coefficients:"
print "1.000, 0.200, 0.300, 0.625"
print "Fit Coefficients:"
print c[0],c[1],abs(c[2]),c[3]

plot(xdata, fitfunc(c, xdata))
plot(xdata, ydata)

title(r'$A = %.3f\  \mu = %.3f\  \sigma = %.3f\ k = %.3f $' %(c[0],c[1],abs(c[2]),c[3]));

show()

Output:

A exp[-0.5((x-mu)/sigma)^2] + k 
Parent Coefficients:
1.000, 0.200, 0.300, 0.625
Fit Coefficients:
0.961231625289 0.197254597618 0.293989275502 0.65370344131

gaussian plot with fit

Merge a Branch into Trunk

If your working directory points to the trunk, then you should be able to merge your branch with:

svn merge https://HOST/repository/branches/branch_1

be sure to be to issue this command in the root directory of your trunk

MySQL Workbench - Connect to a Localhost

enter image description here

I think you want to config your database server firstly after the installation, as shown in picture, you can reconfigure MySql server

Multiple markers Google Map API v3 from array of addresses and avoid OVER_QUERY_LIMIT while geocoding on pageLoad

Answer to add multiple markers.

UPDATE (GEOCODE MULTIPLE ADDRESSES)

Here's the working Example Geocoding with multiple addresses.

 <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false">
 </script> 
 <script type="text/javascript">
  var delay = 100;
  var infowindow = new google.maps.InfoWindow();
  var latlng = new google.maps.LatLng(21.0000, 78.0000);
  var mapOptions = {
    zoom: 5,
    center: latlng,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  var geocoder = new google.maps.Geocoder(); 
  var map = new google.maps.Map(document.getElementById("map"), mapOptions);
  var bounds = new google.maps.LatLngBounds();

  function geocodeAddress(address, next) {
    geocoder.geocode({address:address}, function (results,status)
      { 
         if (status == google.maps.GeocoderStatus.OK) {
          var p = results[0].geometry.location;
          var lat=p.lat();
          var lng=p.lng();
          createMarker(address,lat,lng);
        }
        else {
           if (status == google.maps.GeocoderStatus.OVER_QUERY_LIMIT) {
            nextAddress--;
            delay++;
          } else {
                        }   
        }
        next();
      }
    );
  }
 function createMarker(add,lat,lng) {
   var contentString = add;
   var marker = new google.maps.Marker({
     position: new google.maps.LatLng(lat,lng),
     map: map,
           });

  google.maps.event.addListener(marker, 'click', function() {
     infowindow.setContent(contentString); 
     infowindow.open(map,marker);
   });

   bounds.extend(marker.position);

 }
  var locations = [
           'New Delhi, India',
           'Mumbai, India',
           'Bangaluru, Karnataka, India',
           'Hyderabad, Ahemdabad, India',
           'Gurgaon, Haryana, India',
           'Cannaught Place, New Delhi, India',
           'Bandra, Mumbai, India',
           'Nainital, Uttranchal, India',
           'Guwahati, India',
           'West Bengal, India',
           'Jammu, India',
           'Kanyakumari, India',
           'Kerala, India',
           'Himachal Pradesh, India',
           'Shillong, India',
           'Chandigarh, India',
           'Dwarka, New Delhi, India',
           'Pune, India',
           'Indore, India',
           'Orissa, India',
           'Shimla, India',
           'Gujarat, India'
  ];
  var nextAddress = 0;
  function theNext() {
    if (nextAddress < locations.length) {
      setTimeout('geocodeAddress("'+locations[nextAddress]+'",theNext)', delay);
      nextAddress++;
    } else {
      map.fitBounds(bounds);
    }
  }
  theNext();

</script>

As we can resolve this issue with setTimeout() function.

Still we should not geocode known locations every time you load your page as said by @geocodezip

Another alternatives of these are explained very well in the following links:

How To Avoid GoogleMap Geocode Limit!

Geocode Multiple Addresses Tutorial By Mike Williams

Example by Google Developers

JavaScript Array Push key value

You have to use bracket notation:

var obj = {};
obj[a[i]] = 0;
x.push(obj);

The result will be:

x = [{left: 0}, {top: 0}];

Maybe instead of an array of objects, you just want one object with two properties:

var x = {};

and

x[a[i]] = 0;

This will result in x = {left: 0, top: 0}.

Threads vs Processes in Linux

That depends on a lot of factors. Processes are more heavy-weight than threads, and have a higher startup and shutdown cost. Interprocess communication (IPC) is also harder and slower than interthread communication.

Conversely, processes are safer and more secure than threads, because each process runs in its own virtual address space. If one process crashes or has a buffer overrun, it does not affect any other process at all, whereas if a thread crashes, it takes down all of the other threads in the process, and if a thread has a buffer overrun, it opens up a security hole in all of the threads.

So, if your application's modules can run mostly independently with little communication, you should probably use processes if you can afford the startup and shutdown costs. The performance hit of IPC will be minimal, and you'll be slightly safer against bugs and security holes. If you need every bit of performance you can get or have a lot of shared data (such as complex data structures), go with threads.

Facebook OAuth "The domain of this URL isn't included in the app's domain"

In case this helps anyone else, this started happening for me on an older site when "Valid OAuth Redirect URIs" became mandatory. The site was still using the V4 PHP SDK and the problem was resolved for me by upgrading to the V5 SDK.

How can I check if a date is the same day as datetime.today()?

  • If you need to compare only day of month value than you can use the following code:

    if yourdate.day == datetime.today().day:
        # do something
    
  • If you need to check that the difference between two dates is acceptable then you can use timedelta:

    if (datetime.today() - yourdate).days == 0:
        #do something
    
  • And if you want to compare date part only than you can simply use:

    from datetime import datetime, date
    if yourdatetime.date() < datetime.today().date()
        # do something
    

Note that timedelta has the following format:

datetime.timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]])

So you are able to check diff in days, seconds, msec, minutes and so on depending on what you really need:

from datetime import datetime
if (datetime.today() - yourdate).days == 0:
    #do something

In your case when you need to check that two dates are exactly the same you can use timedelta(0):

from datetime import datetime, timedelta
if (datetime.today() - yourdate) == timedelta(0):
    #do something

MySQL duplicate entry error even though there is no duplicate entry

I know this wasn't the problem in this case, but I had a similar issue of "Duplicate Entry" when creating a composite primary key:

ALTER TABLE table ADD PRIMARY KEY(fieldA,fieldB); 

The error was something like:

#1062 Duplicate entry 'valueA-valueB' for key 'PRIMARY'

So I searched:

select * from table where fieldA='valueA' and fieldB='valueB'

And the output showed just 1 row, no duplicate!

After some time I found out that if you have NULL values in these field you receive these errors. In the end the error message was kind of misleading me.

Batch file to map a drive when the folder name contains spaces

net use "m:\Server01\my folder" /USER:mynetwork\Administrator "Mypassword" /persistent:yes 

does not work?

Git Clone - Repository not found

You should check if you have any other github account marked as "default". When trying to clone a new repo, the client (in my case BitBucket) will try to get the credentials that you have set "as default". Just mark your new credentials "as default" and it will allow you to clone the repo, it worked for me.

What are the differences between JSON and JSONP?

JSONP is a simple way to overcome browser restrictions when sending JSON responses from different domains from the client.

But the practical implementation of the approach involves subtle differences that are often not explained clearly.

Here is a simple tutorial that shows JSON and JSONP side by side.

All the code is freely available at Github and a live version can be found at http://json-jsonp-tutorial.craic.com

How to select distinct rows in a datatable and store into an array

DataTable dt = new DataTable();
dt.Columns.Add("IntValue", typeof(int));
dt.Columns.Add("StringValue", typeof(string));
dt.Rows.Add(1, "1");
dt.Rows.Add(1, "1");
dt.Rows.Add(1, "1");
dt.Rows.Add(2, "2");
dt.Rows.Add(2, "2");

var x = (from r in dt.AsEnumerable()
        select r["IntValue"]).Distinct().ToList();

Handling warning for possible multiple enumeration of IEnumerable

I usually overload my method with IEnumerable and IList in this situation.

public static IEnumerable<T> Method<T>( this IList<T> source ){... }

public static IEnumerable<T> Method<T>( this IEnumerable<T> source )
{
    /*input checks on source parameter here*/
    return Method( source.ToList() );
}

I take care to explain in the summary comments of the methods that calling IEnumerable will perform a .ToList().

The programmer can choose to .ToList() at a higher level if multiple operations are being concatenated and then call the IList overload or let my IEnumerable overload take care of that.

Google Maps API OVER QUERY LIMIT per second limit

The geocoder has quota and rate limits. From experience, you can geocode ~10 locations without hitting the query limit (the actual number probably depends on server loading). The best solution is to delay when you get OVER_QUERY_LIMIT errors, then retry. See these similar posts:

how to write javascript code inside php

Lately I've come across yet another way of putting JS code inside PHP code. It involves Heredoc PHP syntax. I hope it'll be helpful for someone.

<?php
$script = <<< JS

$(function() {
   // js code goes here
});

JS;
?>

After closing the heredoc construction the $script variable contains your JS code that can be used like this:

<script><?= $script ?></script>

The profit of using this way is that modern IDEs recognize JS code inside Heredoc and highlight it correctly unlike using strings. And you're still able to use PHP variables inside of JS code.

CSS: How to position two elements on top of each other, without specifying a height?

First of all, you really should be including the position on absolutely positioned elements or you will come across odd and confusing behavior; you probably want to add top: 0; left: 0 to the CSS for both of your absolutely positioned elements. You'll also want to have position: relative on .container_row if you want the absolutely positioned elements to be positioned with respect to their parent rather than the document's body:

If the element has 'position: absolute', the containing block is established by the nearest ancestor with a 'position' of 'absolute', 'relative' or 'fixed' ...

Your problem is that position: absolute removes elements from the normal flow:

It is removed from the normal flow entirely (it has no impact on later siblings). An absolutely positioned box establishes a new containing block for normal flow children and absolutely (but not fixed) positioned descendants. However, the contents of an absolutely positioned element do not flow around any other boxes.

This means that absolutely positioned elements have no effect whatsoever on their parent element's size and your first <div class="container_row"> will have a height of zero.

So you can't do what you're trying to do with absolutely positioned elements unless you know how tall they're going to be (or, equivalently, you can specify their height). If you can specify the heights then you can put the same heights on the .container_row and everything will line up; you could also put a margin-top on the second .container_row to leave room for the absolutely positioned elements. For example:

http://jsfiddle.net/ambiguous/zVBDc/

Change Bootstrap input focus blue glow

You can use the .form-control selector to match all inputs. For example to change to red:

.form-control:focus {
  border-color: #FF0000;
  box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(255, 0, 0, 0.6);
}

Put it in your custom css file and load it after bootstrap.css. It will apply to all inputs including textarea, select etc...

Where do I put my php files to have Xampp parse them?

in XAMPP the default root is "htdocs" inside the XAMPP folder, if you followed the instructions on the xampp homepage it would be "/opt/lampp/htdocs"

perform an action on checkbox checked or unchecked event on html form

The currently accepted answer doesn't always work.

(To read about the problem and circumstances, read this: Defined function is "Not defined".)

So, you have 3 options:

1 (it has above-mentioned drawback)

<input type="checkbox" onchange="doAlert(this)">

<script>
function doAlert(checkboxElem) {
    if (checkboxElem.checked) {
        alert ('hi');
    } else {
        alert ('bye');
    }
}
</script>

2 and 3

<input type="checkbox" id="foo">

<script>
function doAlert() {
    var input = document.querySelector('#foo');

    // input.addEventListener('change', function() { ... });
    // or
    // input.onchange = function() { ... };
    input.addEventListener('change', function() {
        if (input.checked) {
            alert ('hi');
        } else {
            alert ('bye');
        }
    });
}

doAlert();
</script>

How to use Simple Ajax Beginform in Asp.net MVC 4?

Besides the previous post instructions, I had to install the package Microsoft.jQuery.Unobtrusive.Ajax and add to the view the following line

<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>

How do you synchronise projects to GitHub with Android Studio?

In Android Studio 0.8.2 , you have the same option (ie Share on GitHub). If you want to find it, you can use ctrl+shift+a and enter github in the input text.

Looping through a hash, or using an array in PowerShell

If you're using PowerShell v3, you can use JSON instead of a hashtable, and convert it to an object with Convert-FromJson:

@'
[
    {
        FileName = "Page";
        ObjectName = "vExtractPage";
    },
    {
        ObjectName = "ChecklistItemCategory";
    },
    {
        ObjectName = "ChecklistItem";
    },
]
'@ | 
    Convert-FromJson |
    ForEach-Object {
        $InputFullTableName = '{0}{1}' -f $TargetDatabase,$_.ObjectName

        # In strict mode, you can't reference a property that doesn't exist, 
        #so check if it has an explicit filename firest.
        $outputFileName = $_.ObjectName
        if( $_ | Get-Member FileName )
        {
            $outputFileName = $_.FileName
        }
        $OutputFullFileName = Join-Path $OutputDirectory $outputFileName

        bcp $InputFullTableName out $OutputFullFileName -T -c $ServerOption
    }

How to persist a property of type List<String> in JPA?

When using the Hibernate implementation of JPA , I've found that simply declaring the type as an ArrayList instead of List allows hibernate to store the list of data.

Clearly this has a number of disadvantages compared to creating a list of Entity objects. No lazy loading, no ability to reference the entities in the list from other objects, perhaps more difficulty in constructing database queries. However when you are dealing with lists of fairly primitive types that you will always want to eagerly fetch along with the entity, then this approach seems fine to me.

@Entity
public class Command implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    ArrayList<String> arguments = new ArrayList<String>();


}

Redirecting 404 error with .htaccess via 301 for SEO etc

I came up with the solution and posted it on my blog

http://web.archive.org/web/20130310123646/http://onlinemarketingexperts.com.au/2013/01/how-to-permanently-redirect-301-all-404-missing-pages-in-htaccess/

here is the htaccess code also

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . / [L,R=301]

but I posted other solutions on my blog too, it depends what you need really

Check if one list contains element from the other

There is one method of Collection named retainAll but having some side effects for you reference

Retains only the elements in this list that are contained in the specified collection (optional operation). In other words, removes from this list all of its elements that are not contained in the specified collection.

true if this list changed as a result of the call

Its like

boolean b = list1.retainAll(list2);

Visual Studio debugging/loading very slow

Please make sure you haven't opened Visual Studio in administrator mode

I faced this issue and had to run in normal mode.

How do I create a table based on another table

select * into newtable from oldtable

How to stick <footer> element at the bottom of the page (HTML5 and CSS3)?

just set position: fixed to the footer element (instead of relative)

Jsbin example

Note that you may need to also set a margin-bottom to the main element at least equal to the height of the footer element (e.g. margin-bottom: 1.5em;) otherwise, in some circustances, the bottom area of the main content could be partially overlapped by your footer

Can't find/install libXtst.so.6?

Your problem comes from the 32/64 bit version of your JDK/JRE... Your shared lib is searched for a 32 bit version.

Your default JDK is a 32 bit version. Try to install a 64 bit one by default and relaunch your `.sh file.

jQuery - Detect value change on hidden input field

It is possible to use Object.defineProperty() in order to redefine the 'value' property of the input element and do anything during its changing.

Object.defineProperty() allows us to define a getter and setter for a property, thus controlling it.

replaceWithWrapper($("#hid1")[0], "value", function(obj, property, value) { 
  console.log("new value:", value)
});

function replaceWithWrapper(obj, property, callback) {
  Object.defineProperty(obj, property, new function() {
    var _value = obj[property];
    return {
      set: function(value) {
        _value = value;
        callback(obj, property, value)
      },
      get: function() {
        return _value;
      }
    }
  });
}

$("#hid1").val(4);

https://jsfiddle.net/bvvmhvfk/

What is the most useful script you've written for everyday life?

I wrote a file extraction tool to be used in Linux, that can extract about 20 different file formats and uses the file content, not the file name.

This tool got quite popular, I have a regular stream of people who download it from my blog. Get it here:

Check variable equality against a list of values

You could use an array and indexOf:

if ([1,3,12].indexOf(foo) > -1)

How to disable "prevent this page from creating additional dialogs"?

I know everybody is ethically against this, but I understand there are reasons of practical joking where this is desired. I think Chrome took a solid stance on this by enforcing a mandatory one second separation time between alert messages. This gives the visitor just enough time to close the page or refresh if they're stuck on an annoying prank site.

So to answer your question, it's all a matter of timing. If you alert more than once per second, Chrome will create that checkbox. Here's a simple example of a workaround:

var countdown = 99;
function annoy(){
    if(countdown>0){
        alert(countdown+" bottles of beer on the wall, "+countdown+" bottles of beer! Take one down, pass it around, "+(countdown-1)+" bottles of beer on the wall!");
        countdown--;

        // Time must always be 1000 milliseconds, 999 or less causes the checkbox to appear
        setTimeout(function(){
            annoy();
        }, 1000);
    }
}

// Don't alert right away or Chrome will catch you
setTimeout(function(){
    annoy();
}, 1000);

How to execute Python code from within Visual Studio Code

To extend vlad2135's answer (read his first); that is how you set up Python debugging in Visual Studio Code with Don Jayamanne's great Python extension (which is a pretty full featured IDE for Python these days, and arguably one of Visual Studio Code's best language extensions, IMO).

Basically, when you click the gear icon, it creates a launch.json file in your .vscode directory in your workspace. You can also make this yourself, but it's probably just simpler to let Visual Studio Code do the heavy lifting. Here's an example file:

File launch.json

You'll notice something cool after you generate it. It automatically created a bunch of configurations (most of mine are cut off; just scroll to see them all) with different settings and extra features for different libraries or environments (like Django).

The one you'll probably end up using the most is Python; which is a plain (in my case C)Python debugger and is easiest to work with settings wise.

I'll make a short walkthrough of the JSON attributes for this one, since the others use the pretty much same configuration with only different interpreter paths and one or two different other features there.

  • name: The name of the configuration. A useful example of why you would change it is if you have two Python configurations which use the same type of config, but different arguments. It's what shows up in the box you see on the top left (my box says "python" since I'm using the default Python configuration).
  • type: Interpreter type. You generally don't want to change this one.
  • request: How you want to run your code, and you generally don't want to change this one either. Default value is "launch", but changing it to "attach" allows the debugger to attach to an already running Python process. Instead of changing it, add a configuration of type attach and use that.
  • stopOnEntry: Python debuggers like to have an invisible break-point when you start the program so you can see the entry-point file and where your first line of active code is. It drives some C#/Java programmers like me insane. false if you don't want it, true otherwise.
  • pythonPath: The path to your install of Python. The default value gets the extension level default in the user/workspace settings. Change it here if you want to have different Pythons for different debug processes. Change it in workspace settings if you want to change it for all debug processes set to the default configuration in a project. Change it in user setting to change where the extension finds Pythons across all projects. (4/12/2017 The following was fixed in extension version 0.6.1). Ironically enough, this gets auto-generated wrong. It auto-generates to "${config.python.pythonPath}" which is deprecated in the newer Visual Studio Code versions. It might still work, but you should use "${config:python.pythonPath}" instead for your default first python on your path or Visual Studio Code settings. (4/6/2017 Edit: This should be fixed in the next release. The team committed the fix a few days ago.)
  • program: The initial file that you debugger starts up when you hit run. "${workspaceRoot}" is the root folder you opened up as your workspace (When you go over to the file icon, the base open folder). Another neat trick if you want to get your program running quickly, or you have multiple entry points to your program is to set this to "${file}" which will start debugging at the file you have open and in focus in the moment you hit debug.
  • cwd: The current working directory folder of the project you're running. Usually you'll just want to leave this "${workspaceRoot}".
  • debugOptions: Some debugger flags. The ones in the picture are default flags, you can find more flags in the python debugger pages, I'm sure.
  • args: This isn't actually a default configuration setting, but a useful one nonetheless (and probably what the OP was asking about). These are the command line arguments that you pass in to your program. The debugger passes these in as though they you had typed: python file.py [args] into your terminal; passing each JSON string in the list to the program in order.

You can go here for more information on the Visual Studio Code file variables you can use to configure your debuggers and paths.

You can go here for the extension's own documentation on launch options, with both optional and required attributes.

You can click the Add Configuration button at the bottom right if you don't see the config template already in the file. It'll give you a list to auto generate a configuration for most of the common debug processes out there.

Now, as per vlad's answer, you may add any breakpoints you need as per normal visual debuggers, choose which run configuration you want in the top left dropdown menu and you can tap the green arrow to the left to the configuration name to start your program.

Pro tip: Different people on your team use different IDEs and they probably don't need your configuration files. Visual Studio Code nearly always puts it's IDE files in one place (by design for this purpose; I assume), launch or otherwise so make sure to add directory .vscode/ to your .gitignore if this is your first time generating a Visual Studio Code file (this process will create the folder in your workspace if you don't have it already)!

Force IE8 Into IE7 Compatiblity Mode

one more if you want to switch IE 8 page render in IE 8 standard mode

<meta http-equiv="X-UA-Compatible" content="IE=100" /> <!-- IE8 mode -->

How to convert byte[] to InputStream?

Should be easy to find in the javadocs...

byte[] byteArr = new byte[] { 0xC, 0xA, 0xF, 0xE };
InputStream is = new ByteArrayInputStream(byteArr);

How to hide console window in python?

Some additional info. for situations that'll need the win32gui solution posted by Mohsen Haddadi earlier in this thread:

As of python 361, win32gui & win32con are not part of the python std library. To use them, pywin32 package will need to be installed; now possible via pip.

More background info on pywin32 package is at: How to use the win32gui module with Python?.

Also, to apply discretion while closing a window so as to not inadvertently close any window in the foreground, the resolution could be extended along the lines of the following:

try     :

    import win32gui, win32con;

    frgrnd_wndw = win32gui.GetForegroundWindow();
    wndw_title  = win32gui.GetWindowText(frgrnd_wndw);
    if wndw_title.endswith("python.exe"):
        win32gui.ShowWindow(frgrnd_wndw, win32con.SW_HIDE);
    #endif
except  :
    pass

Subset dataframe by multiple logical conditions of rows to remove

And also

library(dplyr)
data %>% filter(!v1 %in% c("b", "d", "e"))

or

data %>% filter(v1 != "b" & v1 != "d" & v1 != "e")

or

data %>% filter(v1 != "b", v1 != "d", v1 != "e")

Since the & operator is implied by the comma.

Convert InputStream to BufferedReader

BufferedReader can't wrap an InputStream directly. It wraps another Reader. In this case you'd want to do something like:

BufferedReader br = new BufferedReader(new InputStreamReader(is, "UTF-8"));

Why does Date.parse give incorrect results?

While CMS is correct that passing strings into the parse method is generally unsafe, the new ECMA-262 5th Edition (aka ES5) specification in section 15.9.4.2 suggests that Date.parse() actually should handle ISO-formatted dates. The old specification made no such claim. Of course, old browsers and some current browsers still do not provide this ES5 functionality.

Your second example isn't wrong. It is the specified date in UTC, as implied by Date.prototype.toISOString(), but is represented in your local timezone.

How do you do block comments in YAML?

For Visual Studio Code (VSCode) users, the shortcut to comment out multiple lines is to highlight the lines you want to comment and then press:

ctrl + /

Pressing ctrl + / again can also be used to toggle comments off for one or more selected lines.

running php script (php function) in linux bash

php -f test.php

See the manual for full details of running PHP from the command line

Function for C++ struct

Yes, a struct is identical to a class except for the default access level (member-wise and inheritance-wise). (and the extra meaning class carries when used with a template)

Every functionality supported by a class is consequently supported by a struct. You'd use methods the same as you'd use them for a class.

struct foo {
  int bar;
  foo() : bar(3) {}   //look, a constructor
  int getBar() 
  { 
    return bar; 
  }
};

foo f;
int y = f.getBar(); // y is 3

Difference between the annotations @GetMapping and @RequestMapping(method = RequestMethod.GET)

Short answer:

There is no difference in semantic.

Specifically, @GetMapping is a composed annotation that acts as a shortcut for @RequestMapping(method = RequestMethod.GET).

Further reading:

RequestMapping can be used at class level:

This annotation can be used both at the class and at the method level. In most cases, at the method level applications will prefer to use one of the HTTP method specific variants @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, or @PatchMapping.

while GetMapping only applies to method:

Annotation for mapping HTTP GET requests onto specific handler methods.


https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/GetMapping.html

https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestMapping.html

How to have an automatic timestamp in SQLite?

To complement answers above...

If you are using EF, adorn the property with Data Annotation [Timestamp], then go to the overrided OnModelCreating, inside your context class, and add this Fluent API code:

modelBuilder.Entity<YourEntity>()
                .Property(b => b.Timestamp)
                .ValueGeneratedOnAddOrUpdate()
                .IsConcurrencyToken()
                .ForSqliteHasDefaultValueSql("CURRENT_TIMESTAMP");

It will make a default value to every data that will be insert into this table.

"This SqlTransaction has completed; it is no longer usable."... configuration error?

Also check for any long running processes executed from your .NET app against the DB. For example you may be calling a stored procedure or query which does not have enough time to finish which can show in your logs as:

  • Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding.

    • This SqlTransaction has completed; it is no longer usable.

Check the command timeout settings Try to run a trace (profiler) and see what is happening on the DB side...

Show all tables inside a MySQL database using PHP?

How to get tables

1. SHOW TABLES

mysql> USE test;
Database changed
mysql> SHOW TABLES;
+----------------+
| Tables_in_test |
+----------------+
| t1             |
| t2             |
| t3             |
+----------------+
3 rows in set (0.00 sec)

2. SHOW TABLES IN db_name

mysql> SHOW TABLES IN another_db;
+----------------------+
| Tables_in_another_db |
+----------------------+
| t3                   |
| t4                   |
| t5                   |
+----------------------+
3 rows in set (0.00 sec)

3. Using information schema

mysql> SELECT TABLE_NAME
       FROM information_schema.TABLES
       WHERE TABLE_SCHEMA = 'another_db';
+------------+
| TABLE_NAME |
+------------+
| t3         |
| t4         |
| t5         |
+------------+
3 rows in set (0.02 sec)

to OP

you have fetched just 1 row. fix like this:

while ( $tables = $result->fetch_array())
{
    echo $tmp[0]."<br>";
}

and I think, information_schema would be better than SHOW TABLES

SELECT TABLE_NAME
FROM information_schema.TABLES 
WHERE TABLE_SCHEMA = 'your database name'

while ( $tables = $result->fetch_assoc())
{
    echo $tables['TABLE_NAME']."<br>";
}

Git pull after forced update

To receive the new commits

git fetch

Reset

You can reset the commit for a local branch using git reset.

To change the commit of a local branch:

git reset origin/master --hard

Be careful though, as the documentation puts it:

Resets the index and working tree. Any changes to tracked files in the working tree since <commit> are discarded.

If you want to actually keep whatever changes you've got locally - do a --soft reset instead. Which will update the commit history for the branch, but not change any files in the working directory (and you can then commit them).

Rebase

You can replay your local commits on top of any other commit/branch using git rebase:

git rebase -i origin/master

This will invoke rebase in interactive mode where you can choose how to apply each individual commit that isn't in the history you are rebasing on top of.

If the commits you removed (with git push -f) have already been pulled into the local history, they will be listed as commits that will be reapplied - they would need to be deleted as part of the rebase or they will simply be re-included into the history for the branch - and reappear in the remote history on the next push.

Use the help git command --help for more details and examples on any of the above (or other) commands.

Change line width of lines in matplotlib pyplot legend

@ImportanceOfBeingErnest 's answer is good if you only want to change the linewidth inside the legend box. But I think it is a bit more complex since you have to copy the handles before changing legend linewidth. Besides, it can not change the legend label fontsize. The following two methods can not only change the linewidth but also the legend label text font size in a more concise way.

Method 1

import numpy as np
import matplotlib.pyplot as plt

# make some data
x = np.linspace(0, 2*np.pi)

y1 = np.sin(x)
y2 = np.cos(x)

# plot sin(x) and cos(x)
fig = plt.figure()
ax  = fig.add_subplot(111)
ax.plot(x, y1, c='b', label='y1')
ax.plot(x, y2, c='r', label='y2')

leg = plt.legend()
# get the individual lines inside legend and set line width
for line in leg.get_lines():
    line.set_linewidth(4)
# get label texts inside legend and set font size
for text in leg.get_texts():
    text.set_fontsize('x-large')

plt.savefig('leg_example')
plt.show()

Method 2

import numpy as np
import matplotlib.pyplot as plt

# make some data
x = np.linspace(0, 2*np.pi)

y1 = np.sin(x)
y2 = np.cos(x)

# plot sin(x) and cos(x)
fig = plt.figure()
ax  = fig.add_subplot(111)
ax.plot(x, y1, c='b', label='y1')
ax.plot(x, y2, c='r', label='y2')

leg = plt.legend()
# get the lines and texts inside legend box
leg_lines = leg.get_lines()
leg_texts = leg.get_texts()
# bulk-set the properties of all lines and texts
plt.setp(leg_lines, linewidth=4)
plt.setp(leg_texts, fontsize='x-large')
plt.savefig('leg_example')
plt.show()

The above two methods produce the same output image:

output image

How to display the first few characters of a string in Python?

You can 'slice' a string very easily, just like you'd pull items from a list:

a_string = 'This is a string'

To get the first 4 letters:

first_four_letters = a_string[:4]
>>> 'This'

Or the last 5:

last_five_letters = a_string[-5:]
>>> 'string'

So applying that logic to your problem:

the_string = '416d76b8811b0ddae2fdad8f4721ddbe|d4f656ee006e248f2f3a8a93a8aec5868788b927|12a5f648928f8e0b5376d2cc07de8e4cbf9f7ccbadb97d898373f85f0a75c47f '
first_32_chars = the_string[:32]
>>> 416d76b8811b0ddae2fdad8f4721ddbe

Failure during conversion to COFF: file invalid or corrupt

I am using Visual Studio 2010.

This happened to me when I installed .NET 4.5. Uninstall of .NET 4.5 and install of .NET 4.0 helped me and error messages disappeared.

How to use FormData for AJAX file upload?

View:
<label class="btn btn-info btn-file">
Import <input type="file" style="display: none;">
</label>
<Script>
$(document).ready(function () {
                $(document).on('change', ':file', function () {
                    var fileUpload = $(this).get(0);
                    var files = fileUpload.files;
                    var bid = 0;
                    if (files.length != 0) {
                        var data = new FormData();
                        for (var i = 0; i < files.length ; i++) {
                            data.append(files[i].name, files[i]);
                        }
                        $.ajax({
                            xhr: function () {
                                var xhr = $.ajaxSettings.xhr();
                                xhr.upload.onprogress = function (e) {
                                    console.log(Math.floor(e.loaded / e.total * 100) + '%');
                                };
                                return xhr;
                            },
                            contentType: false,
                            processData: false,
                            type: 'POST',
                            data: data,
                            url: '/ControllerX/' + bid,
                            success: function (response) {
                                location.href = 'xxx/Index/';
                            }
                        });
                    }
                });
            });
</Script>
Controller:
[HttpPost]
        public ActionResult ControllerX(string id)
        {
            var files = Request.Form.Files;
...

How to create an empty matrix in R?

The default for matrix is to have 1 column. To explicitly have 0 columns, you need to write

matrix(, nrow = 15, ncol = 0)

A better way would be to preallocate the entire matrix and then fill it in

mat <- matrix(, nrow = 15, ncol = n.columns)
for(column in 1:n.columns){
  mat[, column] <- vector
}

Put quotes around a variable string in JavaScript

Try:

var text = "'" + "http://example.com" + "'";

How to know function return type and argument types?

Well things have changed a little bit since 2011! Now there's type hints in Python 3.5 which you can use to annotate arguments and return the type of your function. For example this:

def greeting(name):
  return 'Hello, {}'.format(name)

can now be written as this:

def greeting(name: str) -> str:
  return 'Hello, {}'.format(name)

As you can now see types, there's some sort of optional static type checking which will help you and your type checker to investigate your code.

for more explanation I suggest to take a look at the blog post on type hints in PyCharm blog.

Customize list item bullets using CSS

In case you do not want to wrap the content in your <li>s with <span>s, you can also use :before like this:

ul {
  list-style: none;
  }
li {
  position: relative;
  padding-left: 15px;
  line-height: 16px;
}
li:before {
  content: '\2022';
  line-height: 16px; /*match the li line-height for vertical centered bullets*/
  position: absolute;
  left: 0;
}
li.huge:before {
  font-size: 30px;
}

li.small:before {
  font-size: 10px;
}

Adjust your font sizes on the :before to whatever you would like.

<ul>
  <li class="huge">huge bullet</li>
  <li class="small">smaller bullet</li>
  <li class="huge">multi line item with custom<br/> sized bullet</li>
  <li>normal bullet</li>
</ul>

How to increase maximum execution time in php

You can try to set_time_limit(n). However, if your PHP setup is running in safe mode, you can only change it from the php.ini file.

How do I move a file from one location to another in Java?

With Java 7 or newer you can use Files.move(from, to, CopyOption... options).

E.g.

Files.move(Paths.get("/foo.txt"), Paths.get("bar.txt"), StandardCopyOption.REPLACE_EXISTING);

See the Files documentation for more details

Parallel foreach with asynchronous lambda

I've created an extension method for this which makes use of SemaphoreSlim and also allows to set maximum degree of parallelism

    /// <summary>
    /// Concurrently Executes async actions for each item of <see cref="IEnumerable<typeparamref name="T"/>
    /// </summary>
    /// <typeparam name="T">Type of IEnumerable</typeparam>
    /// <param name="enumerable">instance of <see cref="IEnumerable<typeparamref name="T"/>"/></param>
    /// <param name="action">an async <see cref="Action" /> to execute</param>
    /// <param name="maxDegreeOfParallelism">Optional, An integer that represents the maximum degree of parallelism,
    /// Must be grater than 0</param>
    /// <returns>A Task representing an async operation</returns>
    /// <exception cref="ArgumentOutOfRangeException">If the maxActionsToRunInParallel is less than 1</exception>
    public static async Task ForEachAsyncConcurrent<T>(
        this IEnumerable<T> enumerable,
        Func<T, Task> action,
        int? maxDegreeOfParallelism = null)
    {
        if (maxDegreeOfParallelism.HasValue)
        {
            using (var semaphoreSlim = new SemaphoreSlim(
                maxDegreeOfParallelism.Value, maxDegreeOfParallelism.Value))
            {
                var tasksWithThrottler = new List<Task>();

                foreach (var item in enumerable)
                {
                    // Increment the number of currently running tasks and wait if they are more than limit.
                    await semaphoreSlim.WaitAsync();

                    tasksWithThrottler.Add(Task.Run(async () =>
                    {
                        await action(item).ContinueWith(res =>
                        {
                            // action is completed, so decrement the number of currently running tasks
                            semaphoreSlim.Release();
                        });
                    }));
                }

                // Wait for all tasks to complete.
                await Task.WhenAll(tasksWithThrottler.ToArray());
            }
        }
        else
        {
            await Task.WhenAll(enumerable.Select(item => action(item)));
        }
    }

Sample Usage:

await enumerable.ForEachAsyncConcurrent(
    async item =>
    {
        await SomeAsyncMethod(item);
    },
    5);

jQuery Change event on an <input> element - any way to retain previous value?

I created these functions based on Joey Guerra's suggestion, thank you for that. I'm elaborating a little bit, perhaps someone can use it. The first function checkDefaults() is called when an input changes, the second is called when the form is submitted using jQuery.post. div.updatesubmit is my submit button, and class 'needsupdate' is an indicator that an update is made but not yet submitted.

function checkDefaults() {
    var changed = false;
        jQuery('input').each(function(){
            if(this.defaultValue != this.value) {
                changed = true;
            }
        });
        if(changed === true) {
            jQuery('div.updatesubmit').addClass("needsupdate");
        } else {
            jQuery('div.updatesubmit').removeClass("needsupdate");
        }
}

function renewDefaults() {
        jQuery('input').each(function(){
            this.defaultValue = this.value;
        });
        jQuery('div.updatesubmit').removeClass("needsupdate");
}

REST API - Use the "Accept: application/json" HTTP Header

Well Curl could be a better option for json representation but in that case it would be difficult to understand the structure of json because its in command line. if you want to get your json on browser you simply remove all the XML Annotations like -

@XmlRootElement(name="person")
@XmlAccessorType(XmlAccessType.NONE)
@XmlAttribute
@XmlElement

from your model class and than run the same url, you have used for xml representation.

Make sure that you have jacson-databind dependency in your pom.xml

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.4.1</version>
</dependency>

Can I have H2 autocreate a schema in an in-memory database?

"By default, when an application calls DriverManager.getConnection(url, ...) and the database specified in the URL does not yet exist, a new (empty) database is created."—H2 Database.

Addendum: @Thomas Mueller shows how to Execute SQL on Connection, but I sometimes just create and populate in the code, as suggested below.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

/** @see http://stackoverflow.com/questions/5225700 */
public class H2MemTest {

    public static void main(String[] args) throws Exception {
        Connection conn = DriverManager.getConnection("jdbc:h2:mem:", "sa", "");
        Statement st = conn.createStatement();
        st.execute("create table customer(id integer, name varchar(10))");
        st.execute("insert into customer values (1, 'Thomas')");
        Statement stmt = conn.createStatement();
        ResultSet rset = stmt.executeQuery("select name from customer");
        while (rset.next()) {
            String name = rset.getString(1);
            System.out.println(name);
        }
    }
}

R: Comment out block of code

Most of the editors take some kind of shortcut to comment out blocks of code. The default editors use something like command or control and single quote to comment out selected lines of code. In RStudio it's Command or Control+/. Check in your editor.

It's still commenting line by line, but they also uncomment selected lines as well. For the Mac RGUI it's command-option ' (I'm imagining windows is control option). For Rstudio it's just Command or Control + Shift + C again.

These shortcuts will likely change over time as editors get updated and different software becomes the most popular R editors. You'll have to look it up for whatever software you have.

Using If else in SQL Select statement

SELECT CASE WHEN IDParent < 1 
            THEN ID 
            ELSE IDParent 
       END AS colname 
FROM yourtable

no matching function for call to ' '

You are passing pointers (Complex*) when your function takes references (const Complex&). A reference and a pointer are entirely different things. When a function expects a reference argument, you need to pass it the object directly. The reference only means that the object is not copied.

To get an object to pass to your function, you would need to dereference your pointers:

Complex::distanta(*firstComplexNumber, *secondComplexNumber);

Or get your function to take pointer arguments.

However, I wouldn't really suggest either of the above solutions. Since you don't need dynamic allocation here (and you are leaking memory because you don't delete what you have newed), you're better off not using pointers in the first place:

Complex firstComplexNumber(81, 93);
Complex secondComplexNumber(31, 19);
Complex::distanta(firstComplexNumber, secondComplexNumber);

align divs to the bottom of their container

The way I solved this was using flexbox. By using flexbox to layout the contents of your container div, you can have flexbox automatically distribute free space to an item above the one you want to have "stick to the bottom".

For example, say this is your container div with some other block elements inside it, and that the blue box (third one down) is a paragraph and the purple box (last one) is the one you want to have "stick to the bottom".

enter image description here

By setting this layout up with flexbox, you can set flex-grow: 1; on just the paragraph (blue box) and, if it is the only thing with flex-grow: 1;, it will be allocated ALL of the remaining space, pushing the element(s) after it to the bottom of the container like this:

enter image description here

(apologies for the terrible, quick-and-dirty graphics)

What is a non-capturing group in regular expressions?

Well I am a JavaScript developer and will try to explain its significance pertaining to JavaScript.

Consider a scenario where you want to match cat is animal when you would like match cat and animal and both should have a is in between them.

 // this will ignore "is" as that's is what we want
"cat is animal".match(/(cat)(?: is )(animal)/) ;
result ["cat is animal", "cat", "animal"]

 // using lookahead pattern it will match only "cat" we can
 // use lookahead but the problem is we can not give anything
 // at the back of lookahead pattern
"cat is animal".match(/cat(?= is animal)/) ;
result ["cat"]

 //so I gave another grouping parenthesis for animal
 // in lookahead pattern to match animal as well
"cat is animal".match(/(cat)(?= is (animal))/) ;
result ["cat", "cat", "animal"]

 // we got extra cat in above example so removing another grouping
"cat is animal".match(/cat(?= is (animal))/) ;
result ["cat", "animal"]

What are the date formats available in SimpleDateFormat class?

Date and time formats are well described below

SimpleDateFormat (Java Platform SE 7) - Date and Time Patterns

There could be n Number of formats you can possibly make. ex - dd/MM/yyyy or YYYY-'W'ww-u or you can mix and match the letters to achieve your required pattern. Pattern letters are as follow.

  • G - Era designator (AD)
  • y - Year (1996; 96)
  • Y - Week Year (2009; 09)
  • M - Month in year (July; Jul; 07)
  • w - Week in year (27)
  • W - Week in month (2)
  • D - Day in year (189)
  • d - Day in month (10)
  • F - Day of week in month (2)
  • E - Day name in week (Tuesday; Tue)
  • u - Day number of week (1 = Monday, ..., 7 = Sunday)
  • a - AM/PM marker
  • H - Hour in day (0-23)
  • k - Hour in day (1-24)
  • K - Hour in am/pm (0-11)
  • h - Hour in am/pm (1-12)
  • m - Minute in hour (30)
  • s - Second in minute (55)
  • S - Millisecond (978)
  • z - General time zone (Pacific Standard Time; PST; GMT-08:00)
  • Z - RFC 822 time zone (-0800)
  • X - ISO 8601 time zone (-08; -0800; -08:00)

To parse:

2000-01-23T04:56:07.000+0000

Use: new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");

How to get jQuery to wait until an effect is finished?

if its something you wish to switch, fading one out and fading another in the same place, you can place a {position:absolute} attribute on the divs, so both the animations play on top of one another, and you don't have to wait for one animation to be over before starting up the next.

C# Timer or Thread.Sleep

I required a thread to fire once every minute (see question here) and I've now used a DispatchTimer based on the answers I received.

The answers provide some references which you might find useful.

Creating a class object in c++

First of all, both cases calls a constructor. If you write

Example *example = new Example();

then you are creating an object, call the constructor and retrieve a pointer to it.

If you write

Example example;

The only difference is that you are getting the object and not a pointer to it. The constructor called in this case is the same as above, the default (no argument) constructor.

As for the singleton question, you must simple invoke your static method by writing:

Example *e = Singleton::getExample();

Can my enums have friendly names?

After reading many resources regarding this topic, including StackOverFlow, I find that not all solutions are working properly. Below is our attempt to fix this.

Basically, We take the friendly name of an Enum from a DescriptionAttribute if it exists.
If it does not We use RegEx to determine the words within the Enum name and add spaces.

Next version, we will use another Attribute to flag whether we can/should take the friendly name from a localizable resource file.

Below are the test cases. Please report if you have another test case that do not pass.

public static class EnumHelper
{
    public static string ToDescription(Enum value)
    {
        if (value == null)
        {
            return string.Empty;
        }

        if (!Enum.IsDefined(value.GetType(), value))
        {
            return string.Empty;
        }

        FieldInfo fieldInfo = value.GetType().GetField(value.ToString());
        if (fieldInfo != null)
        {
            DescriptionAttribute[] attributes =
                fieldInfo.GetCustomAttributes(typeof (DescriptionAttribute), false) as DescriptionAttribute[];
            if (attributes != null && attributes.Length > 0)
            {
                return attributes[0].Description;
            }
        }

        return StringHelper.ToFriendlyName(value.ToString());
    }
}

public static class StringHelper
{
    public static bool IsNullOrWhiteSpace(string value)
    {
        return value == null || string.IsNullOrEmpty(value.Trim());
    }

    public static string ToFriendlyName(string value)
    {
        if (value == null) return string.Empty;
        if (value.Trim().Length == 0) return string.Empty;

        string result = value;

        result = string.Concat(result.Substring(0, 1).ToUpperInvariant(), result.Substring(1, result.Length - 1));

        const string pattern = @"([A-Z]+(?![a-z])|\d+|[A-Z][a-z]+|(?![A-Z])[a-z]+)+";

        List<string> words = new List<string>();
        Match match = Regex.Match(result, pattern);
        if (match.Success)
        {
            Group group = match.Groups[1];
            foreach (Capture capture in group.Captures)
            {
                words.Add(capture.Value);
            }
        }

        return string.Join(" ", words.ToArray());
    }
}


    [TestMethod]
    public void TestFriendlyName()
    {
        string[][] cases =
            {
                new string[] {null, string.Empty},
                new string[] {string.Empty, string.Empty},
                new string[] {" ", string.Empty}, 
                new string[] {"A", "A"},
                new string[] {"z", "Z"},

                new string[] {"Pascal", "Pascal"},
                new string[] {"camel", "Camel"},

                new string[] {"PascalCase", "Pascal Case"}, 
                new string[] {"ABCPascal", "ABC Pascal"}, 
                new string[] {"PascalABC", "Pascal ABC"}, 
                new string[] {"Pascal123", "Pascal 123"}, 
                new string[] {"Pascal123ABC", "Pascal 123 ABC"}, 
                new string[] {"PascalABC123", "Pascal ABC 123"}, 
                new string[] {"123Pascal", "123 Pascal"}, 
                new string[] {"123ABCPascal", "123 ABC Pascal"}, 
                new string[] {"ABC123Pascal", "ABC 123 Pascal"}, 

                new string[] {"camelCase", "Camel Case"}, 
                new string[] {"camelABC", "Camel ABC"}, 
                new string[] {"camel123", "Camel 123"}, 
            };

        foreach (string[] givens in cases)
        {
            string input = givens[0];
            string expected = givens[1];
            string output = StringHelper.ToFriendlyName(input);

            Assert.AreEqual(expected, output);
        }
    }
}

Regular expression for excluding special characters

Why do you consider regex the best tool for this? If your purpose is to detect whether an illegal character is present in a string, testing each character in a loop will be both simpler and more efficient than constructing a regex.

pthread function from a class

The above answers are good, but in my case, 1st approach that converts the function to be a static didn't work. I was trying to convert exiting code to move into thread function but that code had lots to references to non-static class members already. The second solution of encapsulating into C++ object works, but has 3-level wrappers to run a thread.

I had an alternate solution that uses existing C++ construct - 'friend' function, and it worked perfect for my case. An example of how I used 'friend' (will use the above same example for names showing how it can be converted into a compact form using friend)

    class MyThreadClass
    {
    public:
       MyThreadClass() {/* empty */}
       virtual ~MyThreadClass() {/* empty */}

       bool Init()
       {
          return (pthread_create(&_thread, NULL, &ThreadEntryFunc, this) == 0);
       }

       /** Will not return until the internal thread has exited. */
       void WaitForThreadToExit()
       {
          (void) pthread_join(_thread, NULL);
       }

    private:
       //our friend function that runs the thread task
       friend void* ThreadEntryFunc(void *);

       pthread_t _thread;
    };

    //friend is defined outside of class and without any qualifiers
    void* ThreadEntryFunc(void *obj_param) {
    MyThreadClass *thr  = ((MyThreadClass *)obj_param); 

    //access all the members using thr->

    return NULL;
    }

Ofcourse, we can use boost::thread and avoid all these, but I was trying to modify the C++ code to not use boost (the code was linking against boost just for this purpose)

Creating your own header file in C

#ifndef MY_HEADER_H
# define MY_HEADER_H

//put your function headers here

#endif

MY_HEADER_H serves as a double-inclusion guard.

For the function declaration, you only need to define the signature, that is, without parameter names, like this:

int foo(char*);

If you really want to, you can also include the parameter's identifier, but it's not necessary because the identifier would only be used in a function's body (implementation), which in case of a header (parameter signature), it's missing.

This declares the function foo which accepts a char* and returns an int.

In your source file, you would have:

#include "my_header.h"

int foo(char* name) {
   //do stuff
   return 0;
}

How to get the entire document HTML as a string?

The correct way is actually:

webBrowser1.DocumentText

IIs Error: Application Codebehind=“Global.asax.cs” Inherits=“nadeem.MvcApplication”

Problem could occur if you have changed the namespace of your project.

Change the Namespace from Project Properties and also replace all old Namespace with new ones. Renaming to correct namespace might fix the issue.

Source

jQuery: enabling/disabling datepicker

   $("#datepicker").datepicker({
     dateFormat:'dd/M/yy',
     minDate: 'now',
     changeMonth:true,
     changeYear:true,
     showOn: "focus",
    // buttonImage: "YourImage",
     buttonImageOnly: true, 
     yearRange: "-100:+0",  
  }); 

  $( "#datepicker" ).datepicker( "option", "disabled", true ); //missing ID selector

UIBarButtonItem in navigation bar programmatically?

Custom button image without setting button frame:

You can use init(image: UIImage?, style: UIBarButtonItemStyle, target: Any?, action: Selector?) to initializes a new item using the specified image and other properties.

let button1 = UIBarButtonItem(image: UIImage(named: "imagename"), style: .plain, target: self, action: Selector("action")) // action:#selector(Class.MethodName) for swift 3
self.navigationItem.rightBarButtonItem  = button1

Check this Apple Doc. reference


UIBarButtonItem with custom button image using button frame

FOR Swift 3.0

    let btn1 = UIButton(type: .custom)
    btn1.setImage(UIImage(named: "imagename"), for: .normal)
    btn1.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
    btn1.addTarget(self, action: #selector(Class.Methodname), for: .touchUpInside)
    let item1 = UIBarButtonItem(customView: btn1)

    let btn2 = UIButton(type: .custom)
    btn2.setImage(UIImage(named: "imagename"), for: .normal)
    btn2.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
    btn2.addTarget(self, action: #selector(Class.MethodName), for: .touchUpInside)
    let item2 = UIBarButtonItem(customView: btn2)  

    self.navigationItem.setRightBarButtonItems([item1,item2], animated: true)

FOR Swift 2.0 and older

let btnName = UIButton()
btnName.setImage(UIImage(named: "imagename"), forState: .Normal)
btnName.frame = CGRectMake(0, 0, 30, 30)
btnName.addTarget(self, action: Selector("action"), forControlEvents: .TouchUpInside)

//.... Set Right/Left Bar Button item
let rightBarButton = UIBarButtonItem()
rightBarButton.customView = btnName
self.navigationItem.rightBarButtonItem = rightBarButton

Or simply use init(customView:) like

 let rightBarButton = UIBarButtonItem(customView: btnName)
 self.navigationItem.rightBarButtonItem = rightBarButton

For System UIBarButtonItem

let camera = UIBarButtonItem(barButtonSystemItem: .Camera, target: self, action: Selector("btnOpenCamera"))
self.navigationItem.rightBarButtonItem = camera

For set more then 1 items use rightBarButtonItems or for left side leftBarButtonItems

let btn1 = UIButton()
btn1.setImage(UIImage(named: "img1"), forState: .Normal)
btn1.frame = CGRectMake(0, 0, 30, 30)
btn1.addTarget(self, action: Selector("action1:"), forControlEvents: .TouchUpInside)
let item1 = UIBarButtonItem()
item1.customView = btn1

let btn2 = UIButton()
btn2.setImage(UIImage(named: "img2"), forState: .Normal)
btn2.frame = CGRectMake(0, 0, 30, 30)
btn2.addTarget(self, action: Selector("action2:"), forControlEvents: .TouchUpInside)
let item2 = UIBarButtonItem()
item2.customView = btn2

self.navigationItem.rightBarButtonItems = [item1,item2]

Using setLeftBarButtonItem or setRightBarButtonItem

let btn1 = UIButton()
btn1.setImage(UIImage(named: "img1"), forState: .Normal)
btn1.frame = CGRectMake(0, 0, 30, 30)
btn1.addTarget(self, action: Selector("action1:"), forControlEvents: .TouchUpInside)
self.navigationItem.setLeftBarButtonItem(UIBarButtonItem(customView: btn1), animated: true);

For swift >= 2.2 action should be #selector(Class.MethodName) ... for e.g. btnName.addTarget(self, action: #selector(Class.MethodName), forControlEvents: .TouchUpInside)

iOS 7 App Icons, Launch images And Naming Convention While Keeping iOS 6 Icons

You should use Asset Catalog:

I have investigated, how we can use Asset Catalog; Now it seems to be easy for me. I want to show you steps to add icons and splash in asset catalog.

Note: No need to make any entry in info.plist file :) And no any other configuration.

In below image, at right side, you will see highlighted area, where you can mention which icons you need. In case of mine, i have selected first four checkboxes; As its for my app requirements. You can select choices according to your requirements.

enter image description here

Now, see below image. As you will select any App icon then you will see its detail at right side selected area. It will help you to upload correct resolution icon. enter image description here

If Correct resolution image will not be added then following warning will come. Just upload the image with correct resolution. enter image description here

After uploading all required dimensions, you shouldn't get any warning. enter image description here

Delete empty lines using sed

You are most likely seeing the unexpected behavior because your text file was created on Windows, so the end of line sequence is \r\n. You can use dos2unix to convert it to a UNIX style text file before running sed or use

sed -r "/^\r?$/d"

to remove blank lines whether or not the carriage return is there.

Angular 2: import external js file into component

1) First Insert JS file path in an index.html file :

<script src="assets/video.js" type="text/javascript"></script>

2) Import JS file and declare the variable in component.ts :

  • import './../../../assets/video.js';
  • declare var RunPlayer: any;

    NOTE: Variable name should be same as the name of a function in js file

3) Call the js method in the component

ngAfterViewInit(){

    setTimeout(() => {
        new RunPlayer();
    });

}

Setting DataContext in XAML in WPF

First of all you should create property with employee details in the Employee class:

public class Employee
{
    public Employee()
    {
        EmployeeDetails = new EmployeeDetails();
        EmployeeDetails.EmpID = 123;
        EmployeeDetails.EmpName = "ABC";
    }

    public EmployeeDetails EmployeeDetails { get; set; }
}

If you don't do that, you will create instance of object in Employee constructor and you lose reference to it.

In the XAML you should create instance of Employee class, and after that you can assign it to DataContext.

Your XAML should look like this:

<Window x:Class="SampleApplication.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525"
    xmlns:local="clr-namespace:SampleApplication"
   >
    <Window.Resources>
        <local:Employee x:Key="Employee" />
    </Window.Resources>
    <Grid DataContext="{StaticResource Employee}">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="200" />
        </Grid.ColumnDefinitions>

        <Label Grid.Row="0" Grid.Column="0" Content="ID:"/>
        <Label Grid.Row="1" Grid.Column="0" Content="Name:"/>
        <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding EmployeeDetails.EmpID}" />
        <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding EmployeeDetails.EmpName}" />
    </Grid>
</Window>

Now, after you created property with employee details you should binding by using this property:

Text="{Binding EmployeeDetails.EmpID}"

Python matplotlib multiple bars

import matplotlib.pyplot as plt
from matplotlib.dates import date2num
import datetime

x = [
    datetime.datetime(2011, 1, 4, 0, 0),
    datetime.datetime(2011, 1, 5, 0, 0),
    datetime.datetime(2011, 1, 6, 0, 0)
]
x = date2num(x)

y = [4, 9, 2]
z = [1, 2, 3]
k = [11, 12, 13]

ax = plt.subplot(111)
ax.bar(x-0.2, y, width=0.2, color='b', align='center')
ax.bar(x, z, width=0.2, color='g', align='center')
ax.bar(x+0.2, k, width=0.2, color='r', align='center')
ax.xaxis_date()

plt.show()

enter image description here

I don't know what's the "y values are also overlapping" means, does the following code solve your problem?

ax = plt.subplot(111)
w = 0.3
ax.bar(x-w, y, width=w, color='b', align='center')
ax.bar(x, z, width=w, color='g', align='center')
ax.bar(x+w, k, width=w, color='r', align='center')
ax.xaxis_date()
ax.autoscale(tight=True)

plt.show()

enter image description here

kill -3 to get java thread dump

You could alternatively use jstack (Included with JDK) to take a thread dump and write the output wherever you want. Is that not available in a unix environment?

jstack PID > outfile

Declaring array of objects

After seeing how you responded in the comments. It seems like it would be best to use push as others have suggested. This way you don't need to know the indices, but you can still add to the array.

var arr = [];
function funcInJsFile() {
    // Do Stuff
    var obj = {x: 54, y: 10};
    arr.push(obj);
}

In this case, every time you use that function, it will push a new object into the array.

Array formula on Excel for Mac

This doesn't seem to work in Mac Excel 2016. After a bit of digging, it looks like the key combination for entering the array formula has changed from ?+RETURN to CTRL+SHIFT+RETURN.

Select first occurring element after another element

#many .more.selectors h4 + p { ... }

This is called the adjacent sibling selector.

How should I use try-with-resources with JDBC?

As others have stated, your code is basically correct though the outer try is unneeded. Here are a few more thoughts.

DataSource

Other answers here are correct and good, such the accepted Answer by bpgergo. But none of the show the use of DataSource, commonly recommended over use of DriverManager in modern Java.

So for the sake of completeness, here is a complete example that fetches the current date from the database server. The database used here is Postgres. Any other database would work similarly. You would replace the use of org.postgresql.ds.PGSimpleDataSource with an implementation of DataSource appropriate to your database. An implementation is likely provided by your particular driver, or connection pool if you go that route.

A DataSource implementation need not be closed, because it is never “opened”. A DataSource is not a resource, is not connected to the database, so it is not holding networking connections nor resources on the database server. A DataSource is simply information needed when making a connection to the database, with the database server's network name or address, the user name, user password, and various options you want specified when a connection is eventually made. So your DataSource implementation object does not go inside your try-with-resources parentheses.

Nested try-with-resources

Your code makes proper used of nested try-with-resources statements.

Notice in the example code below that we also use the try-with-resources syntax twice, one nested inside the other. The outer try defines two resources: Connection and PreparedStatement. The inner try defines the ResultSet resource. This is a common code structure.

If an exception is thrown from the inner one, and not caught there, the ResultSet resource will automatically be closed (if it exists, is not null). Following that, the PreparedStatement will be closed, and lastly the Connection is closed. Resources are automatically closed in reverse order in which they were declared within the try-with-resource statements.

The example code here is overly simplistic. As written, it could be executed with a single try-with-resources statement. But in a real work you will likely be doing more work between the nested pair of try calls. For example, you may be extracting values from your user-interface or a POJO, and then passing those to fulfill ? placeholders within your SQL via calls to PreparedStatement::set… methods.

Syntax notes

Trailing semicolon

Notice that the semicolon trailing the last resource statement within the parentheses of the try-with-resources is optional. I include it in my own work for two reasons: Consistency and it looks complete, and it makes copy-pasting a mix of lines easier without having to worry about end-of-line semicolons. Your IDE may flag the last semicolon as superfluous, but there is no harm in leaving it.

Java 9 – Use existing vars in try-with-resources

New in Java 9 is an enhancement to try-with-resources syntax. We can now declare and populate the resources outside the parentheses of the try statement. I have not yet found this useful for JDBC resources, but keep it in mind in your own work.

ResultSet should close itself, but may not

In an ideal world the ResultSet would close itself as the documentation promises:

A ResultSet object is automatically closed when the Statement object that generated it is closed, re-executed, or used to retrieve the next result from a sequence of multiple results.

Unfortunately, in the past some JDBC drivers infamously failed to fulfill this promise. As a result, many JDBC programmers learned to explicitly close all their JDBC resources including Connection, PreparedStatement, and ResultSet too. The modern try-with-resources syntax has made doing so easier, and with more compact code. Notice that the Java team went to the bother of marking ResultSet as AutoCloseable, and I suggest we make use of that. Using a try-with-resources around all your JDBC resources makes your code more self-documenting as to your intentions.

Code example

package work.basil.example;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.time.LocalDate;
import java.util.Objects;

public class App
{
    public static void main ( String[] args )
    {
        App app = new App();
        app.doIt();
    }

    private void doIt ( )
    {
        System.out.println( "Hello World!" );

        org.postgresql.ds.PGSimpleDataSource dataSource = new org.postgresql.ds.PGSimpleDataSource();

        dataSource.setServerName( "1.2.3.4" );
        dataSource.setPortNumber( 5432 );

        dataSource.setDatabaseName( "example_db_" );
        dataSource.setUser( "scott" );
        dataSource.setPassword( "tiger" );

        dataSource.setApplicationName( "ExampleApp" );

        System.out.println( "INFO - Attempting to connect to database: " );
        if ( Objects.nonNull( dataSource ) )
        {
            String sql = "SELECT CURRENT_DATE ;";
            try (
                    Connection conn = dataSource.getConnection() ;
                    PreparedStatement ps = conn.prepareStatement( sql ) ;
            )
            {
                … make `PreparedStatement::set…` calls here.
                try (
                        ResultSet rs = ps.executeQuery() ;
                )
                {
                    if ( rs.next() )
                    {
                        LocalDate ld = rs.getObject( 1 , LocalDate.class );
                        System.out.println( "INFO - date is " + ld );
                    }
                }
            }
            catch ( SQLException e )
            {
                e.printStackTrace();
            }
        }

        System.out.println( "INFO - all done." );
    }
}

How do I iterate over a JSON structure?

_x000D_
_x000D_
var arr = [ {"id":"10", "class": "child-of-9"}, {"id":"11", "class": "child-of-10"}];
    
for (var i = 0; i < arr.length; i++){
  document.write("<br><br>array index: " + i);
  var obj = arr[i];
  for (var key in obj){
    var value = obj[key];
    document.write("<br> - " + key + ": " + value);
  }
}
_x000D_
_x000D_
_x000D_

note: the for-in method is cool for simple objects. Not very smart to use with DOM object.

How to show Page Loading div until the page has finished loading?

I have another below simple solution for this which perfectly worked for me.

First of all, create a CSS with name Lockon class which is transparent overlay along with loading GIF as shown below

.LockOn {
    display: block;
    visibility: visible;
    position: absolute;
    z-index: 999;
    top: 0px;
    left: 0px;
    width: 105%;
    height: 105%;
    background-color:white;
    vertical-align:bottom;
    padding-top: 20%; 
    filter: alpha(opacity=75); 
    opacity: 0.75; 
    font-size:large;
    color:blue;
    font-style:italic;
    font-weight:400;
    background-image: url("../Common/loadingGIF.gif");
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-position: center;
}

Now we need to create our div with this class which cover entire page as an overlay whenever the page is getting loaded

<div id="coverScreen"  class="LockOn">
</div>

Now we need to hide this cover screen whenever the page is ready and so that we can restrict the user from clicking/firing any event until the page is ready

$(window).on('load', function () {
$("#coverScreen").hide();
});

Above solution will be fine whenever the page is loading.

Now the question is after the page is loaded, whenever we click a button or an event which will take a long time, we need to show this in the client click event as shown below

$("#ucNoteGrid_grdViewNotes_ctl01_btnPrint").click(function () {
$("#coverScreen").show();
});

That means when we click this print button (which will take a long time to give the report) it will show our cover screen with GIF which gives this result and once the page is ready above windows on load function will fire and which hide the cover screen once the screen is fully loaded.

How to drop all tables from a database with one SQL query?

Use the INFORMATION_SCHEMA.TABLES view to get the list of tables. Generate Drop scripts in the select statement and drop it using Dynamic SQL:

DECLARE @sql NVARCHAR(max)=''

SELECT @sql += ' Drop table ' + QUOTENAME(TABLE_SCHEMA) + '.'+ QUOTENAME(TABLE_NAME) + '; '
FROM   INFORMATION_SCHEMA.TABLES
WHERE  TABLE_TYPE = 'BASE TABLE'

Exec Sp_executesql @sql

Sys.Tables Version

DECLARE @sql NVARCHAR(max)=''

SELECT @sql += ' Drop table ' + QUOTENAME(s.NAME) + '.' + QUOTENAME(t.NAME) + '; '
FROM   sys.tables t
       JOIN sys.schemas s
         ON t.[schema_id] = s.[schema_id]
WHERE  t.type = 'U'

Exec sp_executesql @sql

Note: If you have any foreign Keys defined between tables then first run the below query to disable all foreign keys present in your database.

EXEC sp_msforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"

For more information, check here.

What Regex would capture everything from ' mark to the end of a line?

'.*

I believe you need the option, Multiline.

PIG how to count a number of rows in alias

COUNT is part of pig see the manual

LOGS= LOAD 'log';
LOGS_GROUP= GROUP LOGS ALL;
LOG_COUNT = FOREACH LOGS_GROUP GENERATE COUNT(LOGS);

Adding sheets to end of workbook in Excel (normal method not working?)

mainWB.Sheets.Add(After:=Sheets(Sheets.Count)).Name = new_sheet_name 

should probably be

mainWB.Sheets.Add(After:=mainWB.Sheets(mainWB.Sheets.Count)).Name = new_sheet_name 

Filtering Pandas Dataframe using OR statement

You can do like below to achieve your result:

import seaborn as sns
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
....
....
#use filter with plot
#or
fg=sns.factorplot('Retailer country', data=df1[(df1['Retailer country']=='United States') | (df1['Retailer country']=='France')], kind='count')

fg.set_xlabels('Retailer country')
plt.show()


#also
#and
fg=sns.factorplot('Retailer country', data=df1[(df1['Retailer country']=='United States') & (df1['Year']=='2013')], kind='count')

fg.set_xlabels('Retailer country')
plt.show()

How to check for empty array in vba macro

You can use the below function to check if variant or string array is empty in vba

Function IsArrayAllocated(Arr As Variant) As Boolean
        On Error Resume Next
        IsArrayAllocated = IsArray(Arr) And _
                           Not IsError(LBound(Arr, 1)) And _
                           LBound(Arr, 1) <= UBound(Arr, 1)
End Function

Sample usage

Public Function test()
Dim Arr(1) As String
Arr(0) = "d"
Dim x As Boolean
x = IsArrayAllocated(Arr)
End Function

How to delete node from XML file using C#

It may be easier to use XPath to locate the nodes that you wish to delete. This stackoverflow thread might give you some ideas.

In your case you will find the four nodes that you want using this expression:

XmlDocument doc = new XmlDocument();
doc.Load(fileName);
XmlNodeList nodes = doc.SelectNodes("//Setting[@name='File1']");

FontAwesome icons not showing. Why?

Make sure you include the rel and type as in " rel="stylesheet" type='text/css'" in the link to the awesomefont css file. Without these the file wasn't loading correctly for me.

Output a NULL cell value in Excel

As you've indicated, you can't output NULL in an excel formula. I think this has to do with the fact that the formula itself causes the cell to not be able to be NULL. "" is the next best thing, but sometimes it's useful to use 0.

--EDIT--

Based on your comment, you might want to check out this link. http://peltiertech.com/WordPress/mind-the-gap-charting-empty-cells/

It goes in depth on the graphing issues and what the various values represent, and how to manipulate their output on a chart.

I'm not familiar with VSTO I'm afraid. So I won't be much help there. But if you are really placing formulas in the cell, then there really is no way. ISBLANK() only tests to see if a cell is blank or not, it doesn't have a way to make it blank. It's possible to write code in VBA (and VSTO I imagine) that would run on a worksheet_change event and update the various values instead of using formulas. But that would be cumbersome and performance would take a hit.

Tomcat is not running even though JAVA_HOME path is correct

Try installing java somewhere else - in a directory without spaces. Set again the JAVA_HOME variable and try again. I remember Tomcat had some problems on Window XP with spaces if any variables it was using while starting contained spaces. Maybe it's similar with Windows 7.

I remember I had to change some lines in Tomcat java classes which were handling Tomcat startup.

@Edit: Luciano beat me to noticing it but you should also remove bin from JAVA_HOME

@Edit: I also remember that another fix (didn't test it myself, though) was to set JAVA_HOME to the shorthand version e.g. C:\Progra~1\Java\jdk1.6.0_25

How do you delete an ActiveRecord object?

It's destroy and destroy_all methods, like

user.destroy
User.find(15).destroy
User.destroy(15)
User.where(age: 20).destroy_all
User.destroy_all(age: 20)

Alternatively you can use delete and delete_all which won't enforce :before_destroy and :after_destroy callbacks or any dependent association options.

User.delete_all(condition: 'value') will allow you to delete records without a primary key

Note: from @hammady's comment, user.destroy won't work if User model has no primary key.

Note 2: From @pavel-chuchuva's comment, destroy_all with conditions and delete_all with conditions has been deprecated in Rails 5.1 - see guides.rubyonrails.org/5_1_release_notes.html

Mockito : doAnswer Vs thenReturn

doAnswer and thenReturn do the same thing if:

  1. You are using Mock, not Spy
  2. The method you're stubbing is returning a value, not a void method.

Let's mock this BookService

public interface BookService {
    String getAuthor();
    void queryBookTitle(BookServiceCallback callback);
}

You can stub getAuthor() using doAnswer and thenReturn.

BookService service = mock(BookService.class);
when(service.getAuthor()).thenReturn("Joshua");
// or..
doAnswer(new Answer() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        return "Joshua";
    }
}).when(service).getAuthor();

Note that when using doAnswer, you can't pass a method on when.

// Will throw UnfinishedStubbingException
doAnswer(invocation -> "Joshua").when(service.getAuthor());

So, when would you use doAnswer instead of thenReturn? I can think of two use cases:

  1. When you want to "stub" void method.

Using doAnswer you can do some additionals actions upon method invocation. For example, trigger a callback on queryBookTitle.

BookServiceCallback callback = new BookServiceCallback() {
    @Override
    public void onSuccess(String bookTitle) {
        assertEquals("Effective Java", bookTitle);
    }
};
doAnswer(new Answer() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        BookServiceCallback callback = (BookServiceCallback) invocation.getArguments()[0];
        callback.onSuccess("Effective Java");
        // return null because queryBookTitle is void
        return null;
    }
}).when(service).queryBookTitle(callback);
service.queryBookTitle(callback);
  1. When you are using Spy instead of Mock

When using when-thenReturn on Spy Mockito will call real method and then stub your answer. This can cause a problem if you don't want to call real method, like in this sample:

List list = new LinkedList();
List spy = spy(list);
// Will throw java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
when(spy.get(0)).thenReturn("java");
assertEquals("java", spy.get(0));

Using doAnswer we can stub it safely.

List list = new LinkedList();
List spy = spy(list);
doAnswer(invocation -> "java").when(spy).get(0);
assertEquals("java", spy.get(0));

Actually, if you don't want to do additional actions upon method invocation, you can just use doReturn.

List list = new LinkedList();
List spy = spy(list);
doReturn("java").when(spy).get(0);
assertEquals("java", spy.get(0));

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>)

Not really solve your question but it's an important alternative.

If you want to add custom html to the beginning of the page (inside <body> element), you may use Page.ClientScript.RegisterClientScriptBlock().

Although the method is called "script", but you can add arbitary string, including html.

How to sum data.frame column values?

You can just use sum(people$Weight).

sum sums up a vector, and people$Weight retrieves the weight column from your data frame.

Note - you can get built-in help by using ?sum, ?colSums, etc. (by the way, colSums will give you the sum for each column).

Blur effect on a div element

I think this is what you are looking for? If you are looking to add a blur effect to a div element, you can do this directly through CSS Filters-- See fiddle: http://jsfiddle.net/ayhj9vb0/

 div {
  -webkit-filter: blur(5px);
  -moz-filter: blur(5px);
  -o-filter: blur(5px);
  -ms-filter: blur(5px);
  filter: blur(5px);
  width: 100px;
  height: 100px;
  background-color: #ccc;

}

How to print the contents of RDD?

Instead of typing each time, you can;

[1] Create a generic print method inside Spark Shell.

def p(rdd: org.apache.spark.rdd.RDD[_]) = rdd.foreach(println)

[2] Or even better, using implicits, you can add the function to RDD class to print its contents.

implicit class Printer(rdd: org.apache.spark.rdd.RDD[_]) {
    def print = rdd.foreach(println)
}

Example usage:

val rdd = sc.parallelize(List(1,2,3,4)).map(_*2)

p(rdd) // 1
rdd.print // 2

Output:

2
6
4
8

Important

This only makes sense if you are working in local mode and with a small amount of data set. Otherwise, you either will not be able to see the results on the client or run out of memory because of the big dataset result.

How to revert the last migration?

You can revert by migrating to the previous migration.

For example use below command:

./manage.py migrate example_app one_left_to_the_last_migration

then delete last_migration file.

How can I concatenate a string and a number in Python?

Python is strongly typed. There are no implicit type conversions.

You have to do one of these:

"asd%d" % 9
"asd" + str(9)

"VT-x is not available" when I start my Virtual machine

VT-x can normally be disabled/enabled in your BIOS.

When your PC is just starting up you should press DEL (or something) to get to the BIOS settings. There you'll find an option to enable VT-technology (or something).

select from one table, insert into another table oracle sql query

You can use

insert into <table_name> select <fieldlist> from <tables>

org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class

Just leaving this here for future visitors:

In my case the /WEB-INF/classes directory was missing. If you are using Eclipse, make sure the .settings/org.eclipse.wst.common.component is correct (Deployment Assembly in the project settings).

In my case it was missing

    <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/resources"/>
    <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/test/resources"/>

This file is also a common source of errors as mentioned by Anuj (missing dependencies of other projects).

Otherwise, hopefully the other answers (or the "Problems" tab) will help you.

How to add a class with React.js?

you can also use pure js to accomplish this like the old ways with jquery

try this if you want a simple way

 document.getElementById("myID").classList.add("show-example");

Nginx - Customizing 404 page

You use the error_page property in the nginx config.

For example, if you intend to set the 404 error page to /404.html, use

error_page 404 /404.html;

Setting the 500 error page to /500.html is just as easy as:

error_page 500 /500.html;

Why does "pip install" inside Python raise a SyntaxError?

Initially I too faced this same problem, I installed python and when I run pip command it used to throw me an error like shown in pic below.

enter image description here

Make Sure pip path is added in environmental variables. For me, the python and pip installation path is::
Python: C:\Users\fhhz\AppData\Local\Programs\Python\Python38\
pip: C:\Users\fhhz\AppData\Local\Programs\Python\Python38\Scripts
Both these paths were added to path in environmental variables.

Now Open a new cmd window and type pip, you should be seeing a screen as below.

enter image description here

Now type pip install <<package-name>>. Here I'm installing package spyder so my command line statement will be as pip install spyder and here goes my running screen..

enter image description here

and I hope we are done with this!!

Convert String to Integer in XSLT 1.0

Adding to jelovirt's answer, you can use number() to convert the value to a number, then round(), floor(), or ceiling() to get a whole integer.

Example

<xsl:variable name="MyValAsText" select="'5.14'"/>
<xsl:value-of select="number($MyValAsText) * 2"/> <!-- This outputs 10.28 -->
<xsl:value-of select="floor($MyValAsText)"/> <!-- outputs 5 -->
<xsl:value-of select="ceiling($MyValAsText)"/> <!-- outputs 6 -->
<xsl:value-of select="round($MyValAsText)"/> <!-- outputs 5 -->

How to start up spring-boot application via command line?

Run Spring Boot app using Maven

You can also use Maven plugin to run your Spring Boot app. Use the below example to run your Spring Boot app with Maven plugin:

mvn spring-boot:run

Run Spring Boot App with Gradle

And if you use Gradle you can run the Spring Boot app with the following command:

gradle bootRun

Reset push notification settings for app

After hours of searching, and no luck with the suggestions above, this worked like to a charm for 3.x+

override func viewDidLoad() {
        super.viewDidLoad()


            requestAuthorization()

}

func requestAuthorization() {

        if #available(iOS 10.0, *) {

            UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (granted, error) in
                print("Access granted: \(granted.description)")
            }

        } else {
            // Fallback on earlier versions
        }

    }

All com.android.support libraries must use the exact same version specification

You have defined any other dependency to compile with version 24.0.0 instead of 25.1.1. Please set all dependencies version the same as 25.1.1.

How do I make a WinForms app go Full Screen

I recently made an Mediaplayer application and I used API-calls to make sure the taskbar was hidden when the program was running fullscreen and then restored the taskbar when the program was not in fullscreen or not had focus or was exited.

Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Integer, ByVal hWnd2 As Integer, ByVal lpsz1 As String, ByVal lpsz2 As String) As Integer
Private Declare Function ShowWindow Lib "user32" (ByVal hwnd As Integer, ByVal nCmdShow As Integer) As Integer

Sub HideTrayBar()
    Try


        Dim tWnd As Integer = 0
        Dim bWnd As Integer = 0
        tWnd = FindWindow("Shell_TrayWnd", vbNullString)
        bWnd = FindWindowEx(tWnd, bWnd, "BUTTON", vbNullString)
        ShowWindow(tWnd, 0)
        ShowWindow(bWnd, 0)
    Catch ex As Exception
        'Error hiding the taskbar, do what you want here..
    End Try
End Sub
Sub ShowTraybar()
    Try
        Dim tWnd As Integer = 0
        Dim bWnd As Integer = 0
        tWnd = FindWindow("Shell_TrayWnd", vbNullString)
        bWnd = FindWindowEx(tWnd, bWnd, "BUTTON", vbNullString)
        ShowWindow(bWnd, 1)
        ShowWindow(tWnd, 1)
    Catch ex As Exception
    'Error showing the taskbar, do what you want here..     
               End Try


End Sub

What is an AssertionError? In which case should I throw it from my own code?

AssertionError is an Unchecked Exception which rises explicitly by programmer or by API Developer to indicate that assert statement fails.

assert(x>10);

Output:

AssertionError

If x is not greater than 10 then you will get runtime exception saying AssertionError.

How to increment a variable on a for loop in jinja template?

if anyone want to add a value inside loop then you can use this its working 100%

{% set ftotal= {'total': 0} %} 
{%- for pe in payment_entry -%}
    {% if ftotal.update({'total': ftotal.total + 5}) %}{% endif %} 
{%- endfor -%}

{{ftotal.total}}

output = 5

Find a class somewhere inside dozens of JAR files?

Script to find jar file: find_jar.sh

IFS=$(echo -en "\n\b") # Set the field separator newline

for f in `find ${1} -iname *.jar`; do
  jar -tf ${f}| grep --color $2
  if [ $? == 0 ]; then
    echo -n "Match found: "
    echo -e "${f}\n"
  fi
done
unset IFS

Usage: ./find_jar.sh < top-level directory containing jar files > < Class name to find>

This is similar to most answers given here. But it only outputs the file name, if grep finds something. If you want to suppress grep output you may redirect that to /dev/null but I prefer seeing the output of grep as well so that I can use partial class names and figure out the correct one from a list of output shown.

The class name can be both simple class name Like "String" or fully qualified name like "java.lang.String"

Fixing the order of facets in ggplot

Here's a solution that keeps things within a dplyr pipe chain. You sort the data in advance, and then using mutate_at to convert to a factor. I've modified the data slightly to show how this solution can be applied generally, given data that can be sensibly sorted:

# the data
temp <- data.frame(type=rep(c("T", "F", "P"), 4),
                    size=rep(c("50%", "100%", "200%", "150%"), each=3), # cannot sort this
                    size_num = rep(c(.5, 1, 2, 1.5), each=3), # can sort this
                    amount=c(48.4, 48.1, 46.8, 
                             25.9, 26.0, 24.9,
                             20.8, 21.5, 16.5,
                             21.1, 21.4, 20.1))

temp %>% 
  arrange(size_num) %>% # sort
  mutate_at(vars(size), funs(factor(., levels=unique(.)))) %>% # convert to factor

  ggplot() + 
  geom_bar(aes(x = type, y=amount, fill=type), 
           position="dodge", stat="identity") + 
  facet_grid(~ size)

You can apply this solution to arrange the bars within facets, too, though you can only choose a single, preferred order:

    temp %>% 
  arrange(size_num) %>%
  mutate_at(vars(size), funs(factor(., levels=unique(.)))) %>%
  arrange(desc(amount)) %>%
  mutate_at(vars(type), funs(factor(., levels=unique(.)))) %>%
  ggplot() + 
  geom_bar(aes(x = type, y=amount, fill=type), 
           position="dodge", stat="identity") + 
  facet_grid(~ size)


  ggplot() + 
  geom_bar(aes(x = type, y=amount, fill=type), 
           position="dodge", stat="identity") + 
  facet_grid(~ size)

How to get first N number of elements from an array

arr.length = n

This might be surprising but length property of an array is not only used to get number of array elements but it's also writable and can be used to set array's length MDN link. This will mutate the array.

If you don't care about immutability or don't want to allocate memory i.e. for a game this will be the fastest way.

to empty an array

arr.length = 0

How to update a single pod without touching other dependencies

Make sure you have the latest version of CocoaPods installed. $ pod update POD was introduced recently.

See this issue thread for more information:

$ pod update

When you run pod update SomePodName, CocoaPods will try to find an updated version of the pod SomePodName, without taking into account the version listed in Podfile.lock. It will update the pod to the latest version possible (as long as it matches the version restrictions in your Podfile).

If you run pod update without any pod name, CocoaPods will update every pod listed in your Podfile to the latest version possible.

Get file name from a file location in Java

From Apache Commons IO FileNameUtils

String fileName = FilenameUtils.getName(stringNameWithPath);

jQuery - Add ID instead of Class

if you want to 'add to the id' rather than replace it

capture the current id first, then append your new id. especially useful for twitter bootstrap which uses input states on their forms.

    new_id = '{{old_id}} inputSuccess';
    old_id = that.attr('id');
    that.attr('id', new_id.replace( /{{old_id}}/ig,old_id));

if you do not - you will lose any properties you previous set.

hth,

List append() in for loop

No need to re-assign.

a=[]
for i in range(5):    
    a.append(i)
a

Consider defining a bean of type 'package' in your configuration [Spring-Boot]

This can also happen if you are using Lombok and you add the @RequiredArgsConstructor and @NonNull for fields but some of your fields are not to be injected in the constructor. This is only one of the possibilities to get the the same error.

parameter 0 required a bean of type MissingBeanName that could not be found

In my case the error told me what Controller the problem was in, after removing @NonNull the application started fine

Android: Go back to previous activity

You can try this:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

        finish();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

'printf' with leading zeros in C

Your format specifier is incorrect. From the printf() man page on my machine:

0 A zero '0' character indicating that zero-padding should be used rather than blank-padding. A '-' overrides a '0' if both are used;

Field Width: An optional digit string specifying a field width; if the output string has fewer characters than the field width it will be blank-padded on the left (or right, if the left-adjustment indicator has been given) to make up the field width (note that a leading zero is a flag, but an embedded zero is part of a field width);

Precision: An optional period, '.', followed by an optional digit string giving a precision which specifies the number of digits to appear after the decimal point, for e and f formats, or the maximum number of characters to be printed from a string; if the digit string is missing, the precision is treated as zero;

For your case, your format would be %09.3f:

#include <stdio.h>

int main(int argc, char **argv)
{
  printf("%09.3f\n", 4917.24);
  return 0;
}

Output:

$ make testapp
cc     testapp.c   -o testapp
$ ./testapp 
04917.240

Note that this answer is conditional on your embedded system having a printf() implementation that is standard-compliant for these details - many embedded environments do not have such an implementation.

How to read PDF files using Java?

PDFBox contains tools for text extraction.

iText has more low-level support for text manipulation, but you'd have to write a considerable amount of code to get text extraction.

iText in Action contains a good overview of the limitations of text extraction from PDF, regardless of the library used (Section 18.2: Extracting and editing text), and a convincing explanation why the library does not have text extraction support. In short, it's relatively easy to write a code that will handle simple cases, but it's basically impossible to extract text from PDF in general.