Programs & Examples On #Autocmd

Vim commands you can specify to be executed automatically when reading or writing a file, when entering or leaving a buffer or window, and when exiting Vim

Android: How to change CheckBox size?

I use

android:scaleX="0.70" android:scaleY="0.70"

to ajust the size of checkbox

then I set margins like this

android:layout_marginLeft="-10dp"

to adjust ths location of the checkbox.

How to loop through elements of forms with JavaScript?

$(function() {
    $('form button').click(function() {
        var allowSubmit = true;
        $.each($('form input:text'), function(index, formField) {
            if($(formField).val().trim().length == 0) {
                alert('field is empty!');
                allowSubmit = false;
            }
        });
        return allowSubmit;
    });
});

DEMO

Creating an XmlNode/XmlElement in C# without an XmlDocument?

From W3C Document Object Model (Core) Level 1 specification (bold is mine):

Most of the APIs defined by this specification are interfaces rather than classes. That means that an actual implementation need only expose methods with the defined names and specified operation, not actually implement classes that correspond directly to the interfaces. This allows the DOM APIs to be implemented as a thin veneer on top of legacy applications with their own data structures, or on top of newer applications with different class hierarchies. This also means that ordinary constructors (in the Java or C++ sense) cannot be used to create DOM objects, since the underlying objects to be constructed may have little relationship to the DOM interfaces. The conventional solution to this in object-oriented design is to define factory methods that create instances of objects that implement the various interfaces. In the DOM Level 1, objects implementing some interface "X" are created by a "createX()" method on the Document interface; this is because all DOM objects live in the context of a specific Document.

AFAIK, you can not create any XmlNode (XmlElement, XmlAttribute, XmlCDataSection, etc) except XmlDocument from a constructor.

Moreover, note that you can not use XmlDocument.AppendChild() for nodes that are not created via the factory methods of the same document. In case you have a node from another document, you must use XmlDocument.ImportNode().

write() versus writelines() and concatenated strings

Exercise 16 from Zed Shaw's book? You can use escape characters as follows:

paragraph1 = "%s \n %s \n %s \n" % (line1, line2, line3)
target.write(paragraph1)
target.close()

What are callee and caller saved registers?

The caller-saved / callee-saved terminology is based on a pretty braindead inefficient model of programming where callers actually do save/restore all the call-clobbered registers (instead of keeping long-term-useful values elsewhere), and callees actually do save/restore all the call-preserved registers (instead of just not using some or any of them).

Or you have to understand that "caller-saved" means "saved somehow if you want the value later".

In reality, efficient code lets values get destroyed when they're no longer needed. Compilers typically make functions that save a few call-preserved registers at the start of a function (and restore them at the end). Inside the function, they use those regs for values that need to survive across function calls.

I prefer "call-preserved" vs. "call-clobbered", which are unambiguous and self-describing once you've heard of the basic concept, and don't require any serious mental gymnastics to think about from the caller's perspective or the callee's perspective. (Both terms are from the same perspective).

Plus, these terms differ by more than one letter.

The terms volatile / non-volatile are pretty good, by analogy with storage which loses its value on power-loss or not, (like DRAM vs. Flash). But the C volatile keyword has a totally different technical meaning, so that's a downside to "(non)-volatile" when describing C calling conventions.


  • Call-clobbered, aka caller-saved or volatile registers are good for scratch / temporary values that aren't needed after the next function call.

From the callee's perspective, your function can freely overwrite (aka clobber) these registers without saving/restoring.

From a caller's perspective, call foo destroys (aka clobbers) all the call-clobbered registers, or at least you have to assume it does.

You can write private helper functions that have a custom calling convention, e.g. you know they don't modify a certain register. But if all you know (or want to assume or depend on) is that the target function follows the normal calling convention, then you have to treat a function call as if it does destroy all the call-clobbered registers. That's literally what the name come from: a call clobbers those registers.

Some compilers that do inter-procedural optimization can also create internal-use-only definitions of functions that don't follow the ABI, using a custom calling convention.

  • Call-preserved, aka callee-saved or non-volatile registers keep their values across function calls. This is useful for loop variables in a loop that makes function calls, or basically anything in a non-leaf function in general.

From a callee's perspective, these registers can't be modified unless you save the original value somewhere so you can restore it before returning. Or for registers like the stack pointer (which is almost always call-preserved), you can subtract a known offset and add it back again before returning, instead of actually saving the old value anywhere. i.e. you can restore it by dead reckoning, unless you allocate a runtime-variable amount of stack space. Then typically you restore the stack pointer from another register.

A function that can benefit from using a lot of registers can save/restore some call-preserved registers just so it can use them as more temporaries, even if it doesn't make any function calls. Normally you'd only do this after running out of call-clobbered registers to use, because save/restore typically costs a push/pop at the start/end of the function. (Or if your function has multiple exit paths, a pop in each of them.)


The name "caller-saved" is misleading: you don't have to specially save/restore them. Normally you arrange your code to have values that need to survive a function call in call-preserved registers, or somewhere on the stack, or somewhere else that you can reload from. It's normal to let a call destroy temporary values.


An ABI or calling convention defines which are which

See for example What registers are preserved through a linux x86-64 function call for the x86-64 System V ABI.

Also, arg-passing registers are always call-clobbered in all function-calling conventions I'm aware of. See Are rdi and rsi caller saved or callee saved registers?

But system-call calling conventions typically make all the registers except the return value call-preserved. (Usually including even condition-codes / flags.) See What are the calling conventions for UNIX & Linux system calls on i386 and x86-64

Python conversion from binary string to hexadecimal

To convert binary string to hexadecimal string, we don't need any external libraries. Use formatted string literals (known as f-strings). This feature was added in python 3.6 (PEP 498)

>>> bs = '0000010010001101'
>>> hexs = f'{int(bs, 2):X}'
>>> print(hexs)
>>> '48D'

If you want hexadecimal strings in small-case, use small "x" as follows

f'{int(bs, 2):x}'

Where bs inside f-string is a variable which contains binary strings assigned prior

f-strings are lost more useful and effective. They are not being used at their full potential.

Disable browser 'Save Password' functionality

This is my html code for solution. It works for Chrome-Safari-Internet Explorer. I created new font which all characters seem as "?". Then I use this font for my password text. Note: My font name is "passwordsecretregular".

<style type="text/css">
         #login_parola {
             font-family: 'passwordsecretregular' !important;
            -webkit-text-security: disc !important;
            font-size: 22px !important;
         }
    </style>


<input type="text" class="w205 has-keyboard-alpha"  name="login_parola" id="login_parola" onkeyup="checkCapsWarning(event)"  
   onfocus="checkCapsWarning(event)" onblur="removeCapsWarning()" onpaste="return false;" maxlength="32"/>

jquery Ajax call - data parameters are not being passed to MVC Controller action

In my case, if I remove the the contentType, I get the Internal Server Error.

This is what I got working after multiple attempts:

var request =  $.ajax({
    type: 'POST',
    url: '/ControllerName/ActionName' ,
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({ projId: 1, userId:1 }), //hard-coded value used for simplicity
    dataType: 'json'
});

request.done(function(msg) {
    alert(msg);
});

request.fail(function (jqXHR, textStatus, errorThrown) {
    alert("Request failed: " + jqXHR.responseStart +"-" + textStatus + "-" + errorThrown);
});

And this is the controller code:

public JsonResult ActionName(int projId, int userId)
{
    var obj = new ClassName();

    var result = obj.MethodName(projId, userId); // variable used for readability
    return Json(result, JsonRequestBehavior.AllowGet);
}

Please note, the case of ASP.NET is little different, we have to apply JSON.stringify() to the data as mentioned in the update of this answer.

How to download a file from my server using SSH (using PuTTY on Windows)

You can use the WinSPC program. Its access to any server is pretty easy. The program gives its guide too. I hope it's helpfull.

How to check edittext's text is email address or not?

I wrote a library that extends EditText which supports natively some validation methods and is actually very flexible.

Current, as I write, natively supported (through xml attributes) validation methods are:

  1. regexp: for custom regexp
  2. numeric: for an only numeric field
  3. alpha: for an alpha only field
  4. alphaNumeric: guess what?
  5. email: checks that the field is a valid email
  6. creditCard: checks that the field contains a valid credit card using Luhn Algorithm
  7. phone: checks that the field contains a valid phone number
  8. domainName: checks that field contains a valid domain name ( always passes the test in API Level < 8 )
  9. ipAddress: checks that the field contains a valid ip address webUrl: checks that the field contains a valid url ( always passes the test in API Level < 8 )
  10. nocheck: It does not check anything. (Default)

You can check it out here: https://github.com/vekexasia/android-form-edittext

Hope you enjoy it :)

In the page I linked you'll be able to find also an example for email validation. I'll copy the relative snippet here:

<com.andreabaccega.widget.FormEditText
       style="@android:style/Widget.EditText"
       whatever:test="email"
       android:id="@+id/et_email"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:hint="@string/hint_email"
       android:inputType="textEmailAddress"
       />  

There is also a test app showcasing the library possibilities.

This is a screenshot of the app validating the email field.

email validation done thorugh xml+library

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

Get a substring of a char*

Use char* strncpy(char* dest, char* src, int n) from <cstring>. In your case you will need to use the following code:

char* substr = malloc(4);
strncpy(substr, buff+10, 4);

Full documentation on the strncpy function here.

In Java, how do you determine if a thread is running?

I think you can use GetState(); It can return the exact state of a thread.

How to keep the local file or the remote file during merge using Git and the command line?

For the line-end thingie, refer to man git-merge:

--ignore-space-change 
--ignore-all-space 
--ignore-space-at-eol

Be sure to add autocrlf = false and/or safecrlf = false to the windows clone (.git/config)

Using git mergetool

If you configure a mergetool like this:

git config mergetool.cp.cmd '/bin/cp -v "$REMOTE" "$MERGED"'
git config mergetool.cp.trustExitCode true

Then a simple

git mergetool --tool=cp
git mergetool --tool=cp -- paths/to/files.txt
git mergetool --tool=cp -y -- paths/to/files.txt # without prompting

Will do the job

Using simple git commands

In other cases, I assume

git checkout HEAD -- path/to/myfile.txt

should do the trick

Edit to do the reverse (because you screwed up):

git checkout remote/branch_to_merge -- path/to/myfile.txt

What is the "-->" operator in C/C++?

The usage of --> has historical relevance. Decrementing was (and still is in some cases), faster than incrementing on the x86 architecture. Using --> suggests that x is going to 0, and appeals to those with mathematical backgrounds.

What function is to replace a substring from a string in C?

Here is the one that I created based on these requirements:

  1. Replace the pattern regardless of whether is was long or shorter.

  2. Not use any malloc (explicit or implicit) to intrinsically avoid memory leaks.

  3. Replace any number of occurrences of pattern.

  4. Tolerate the replace string having a substring equal to the search string.

  5. Does not have to check that the Line array is sufficient in size to hold the replacement. e.g. This does not work unless the caller knows that line is of sufficient size to hold the new string.

/* returns number of strings replaced.
*/
int replacestr(char *line, const char *search, const char *replace)
{
   int count;
   char *sp; // start of pattern

   //printf("replacestr(%s, %s, %s)\n", line, search, replace);
   if ((sp = strstr(line, search)) == NULL) {
      return(0);
   }
   count = 1;
   int sLen = strlen(search);
   int rLen = strlen(replace);
   if (sLen > rLen) {
      // move from right to left
      char *src = sp + sLen;
      char *dst = sp + rLen;
      while((*dst = *src) != '\0') { dst++; src++; }
   } else if (sLen < rLen) {
      // move from left to right
      int tLen = strlen(sp) - sLen;
      char *stop = sp + rLen;
      char *src = sp + sLen + tLen;
      char *dst = sp + rLen + tLen;
      while(dst >= stop) { *dst = *src; dst--; src--; }
   }
   memcpy(sp, replace, rLen);

   count += replacestr(sp + rLen, search, replace);

   return(count);
}

Any suggestions for improving this code are cheerfully accepted. Just post the comment and I will test it.

Programmatically find the number of cores on a machine

you can use WMI in .net too but you're then dependent on the wmi service running etc. Sometimes it works locally, but then fail when the same code is run on servers. I believe that's a namespace issue, related to the "names" whose values you're reading.

CMD command to check connected USB devices

You could use wmic command:

wmic logicaldisk where drivetype=2 get <DeviceID, VolumeName, Description, ...>

Drivetype 2 indicates that its a removable disk.

how to set the default value to the drop down list control?

if you know the index of the item of default value,just

lstDepartment.SelectedIndex = 1;//the second item

or if you know the value you want to set, just

lstDepartment.SelectedValue = "the value you want to set";

Can I compile all .cpp files in src/ to .o's in obj/, then link to binary in ./?

Makefile part of the question

This is pretty easy, unless you don't need to generalize try something like the code below (but replace space indentation with tabs near g++)

SRC_DIR := .../src
OBJ_DIR := .../obj
SRC_FILES := $(wildcard $(SRC_DIR)/*.cpp)
OBJ_FILES := $(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(SRC_FILES))
LDFLAGS := ...
CPPFLAGS := ...
CXXFLAGS := ...

main.exe: $(OBJ_FILES)
   g++ $(LDFLAGS) -o $@ $^

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
   g++ $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<

Automatic dependency graph generation

A "must" feature for most make systems. With GCC in can be done in a single pass as a side effect of the compilation by adding -MMD flag to CXXFLAGS and -include $(OBJ_FILES:.o=.d) to the end of the makefile body:

CXXFLAGS += -MMD
-include $(OBJ_FILES:.o=.d)

And as guys mentioned already, always have GNU Make Manual around, it is very helpful.

How do I use MySQL through XAMPP?

<?php
if(!@mysql_connect('127.0.0.1', 'root', '*your default password*'))
{
    echo "mysql not connected ".mysql_error();
    exit;

}
echo 'great work';
?>

if no error then you will get greatwork as output.

Try it saved my life XD XD

What is the difference between 'protected' and 'protected internal'?

Think about protected internal as applying two access modifier (protected, and internal) on the same field, property or method.

In the real world, imagine we are issuing privilege for people to visit museum:

  1. Everyone inside the city are allowed to visit museum (internal).
  2. Everyone outside of the city that their parents live here are allowed to visit museum (protected).

And we can put them together in these way:

Everyone inside the city (internal) and everyone outside of city that their parents live here (protected) are allowed to visit the museum (protected internal).

Programming world:

internal: The field is available everywhere in the assembly (project). It is like saying it is public in its project scope (but can not being accessed outside of project scope even by those classes outside of assembly which inherit from that class). Every instance of that type can see it in that assembly (project scope).

protected: simply means that all derived classes can see it (inside or outside of assembly). For example derived classes can see the field or method inside its methods and constructors using: base.NameOfProtectedInternal.

So, putting these two access modifier together (protected internal), you have something that can being public inside the project, and can be seen by those which have inherited from that class inside their scope.

They can be written in the internal protected, and does not change the meaning, but it is convenient to write it protected internal.

How do I sort a VARCHAR column in SQL server that contains numbers?

This seems to work:

select your_column  
from your_table  
order by   
case when isnumeric(your_column) = 1 then your_column else 999999999 end,  
your_column   

Is there a quick change tabs function in Visual Studio Code?

I couldn't find a post for VS Community, so I'll post my solution here.


First, you need to go to Tools -> Options -> Environment -> Keyboard, then find the command Window.NextTab. Near the bottom it should say "Use new shortcut in: ". Set that to Global (should be default), then select the textbox to the right and hit Ctrl + Tab. Remove all current shortcuts for the selected command, and hit Assign. For Ctrl + Shift + Tab, the command should be Window.PreviousTab.

Hope this helps :) If there's a separate post for VS Community, I'd gladly move this post over.

Django Cookies, how can I set them?

Anyone interested in doing this should read the documentation of the Django Sessions framework. It stores a session ID in the user's cookies, but maps all the cookies-like data to your database. This is an improvement on the typical cookies-based workflow for HTTP requests.

Here is an example with a Django view ...

def homepage(request):

    request.session.setdefault('how_many_visits', 0)
    request.session['how_many_visits'] += 1

    print(request.session['how_many_visits'])

    return render(request, 'home.html', {})

If you keep visiting the page over and over, you'll see the value start incrementing up from 1 until you clear your cookies, visit on a new browser, go incognito, or do anything else that sidesteps Django's Session ID cookie.

How to construct a set out of list items in python?

You can also use list comprehension to create set.

s = {i for i in range(5)}

Windows: XAMPP vs WampServer vs EasyPHP vs alternative

I'm using EasyPHP in making my Thesis about Content Management System. So far, this tool is very good and easy to use.

get url content PHP

Try using cURL instead. cURL implements a cookie jar, while file_get_contents doesn't.

Uncaught TypeError: Cannot read property 'value' of undefined

The posts here help me a lot on my way to find a solution for the Uncaught TypeError: Cannot read property 'value' of undefined issue.

There are already here many answers which are correct, but what we don't have here is the combination for 2 answers that i think resolve this issue completely.

function myFunction(field, data){
  if (typeof document.getElementsByName("+field+")[0] != 'undefined'){
  document.getElementsByName("+field+")[0].value=data;
 }
}

The difference is that you make a check(if a property is defined or not) and if the check is true then you can try to assign it a value.

Windows service start failure: Cannot start service from the command line or debugger

To install your service manually

To install or uninstall windows service manually (which was created using .NET Framework) use utility InstallUtil.exe. This tool can be found in the following path (use appropriate framework version number).

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\InstallUtil.exe

To install

installutil yourproject.exe

To uninstall

installutil /u yourproject.exe

See: How to: Install and Uninstall Services (Microsoft)

Install service programmatically

To install service programmatically using C# see the following class ServiceInstaller (c-sharpcorner).

Are strongly-typed functions as parameters possible in TypeScript?

Because you can't easily union a function definition and another data type, I find having these types around useful to strongly type them. Based on Drew's answer.

type Func<TArgs extends any[], TResult> = (...args: TArgs) => TResult; 
//Syntax sugar
type Action<TArgs extends any[]> = Func<TArgs, undefined>; 

Now you can strongly type every parameter and the return type! Here's an example with more parameters than what is above.

save(callback: Func<[string, Object, boolean], number>): number
{
    let str = "";
    let obj = {};
    let bool = true;
    let result: number = callback(str, obj, bool);
    return result;
}

Now you can write a union type, like an object or a function returning an object, without creating a brand new type that may need to be exported or consumed.

//THIS DOESN'T WORK
let myVar1: boolean | (parameters: object) => boolean;

//This works, but requires a type be defined each time
type myBoolFunc = (parameters: object) => boolean;
let myVar1: boolean | myBoolFunc;

//This works, with a generic type that can be used anywhere
let myVar2: boolean | Func<[object], boolean>;

Pure CSS collapse/expand div

Using <summary> and <details>

Using <summary> and <details> elements is the simplest but see browser support as current IE is not supporting it. You can polyfill though (most are jQuery-based). Do note that unsupported browser will simply show the expanded version of course, so that may be acceptable in some cases.

_x000D_
_x000D_
/* Optional styling */_x000D_
summary::-webkit-details-marker {_x000D_
  color: blue;_x000D_
}_x000D_
summary:focus {_x000D_
  outline-style: none;_x000D_
}
_x000D_
<details>_x000D_
  <summary>Summary, caption, or legend for the content</summary>_x000D_
  Content goes here._x000D_
</details>
_x000D_
_x000D_
_x000D_

See also how to style the <details> element (HTML5 Doctor) (little bit tricky).

Pure CSS3

The :target selector has a pretty good browser support, and it can be used to make a single collapsible element within the frame.

_x000D_
_x000D_
.details,_x000D_
.show,_x000D_
.hide:target {_x000D_
  display: none;_x000D_
}_x000D_
.hide:target + .show,_x000D_
.hide:target ~ .details {_x000D_
  display: block;_x000D_
}
_x000D_
<div>_x000D_
  <a id="hide1" href="#hide1" class="hide">+ Summary goes here</a>_x000D_
  <a id="show1" href="#show1" class="show">- Summary goes here</a>_x000D_
  <div class="details">_x000D_
    Content goes here._x000D_
  </div>_x000D_
</div>_x000D_
<div>_x000D_
  <a id="hide2" href="#hide2" class="hide">+ Summary goes here</a>_x000D_
  <a id="show2" href="#show2" class="show">- Summary goes here</a>_x000D_
  <div class="details">_x000D_
    Content goes here._x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to get calendar Quarter from a date in TSQL

Here you see one of the more alternatives :

SELECT CASE
         WHEN @TODAY BETWEEN @FY_START AND DATEADD(M, 3, @FY_START) THEN 'Q1'
         WHEN @TODAY BETWEEN DATEADD(M, 3, @FY_START) AND DATEADD(M, 6, @FY_START) THEN 'Q2'
         WHEN @TODAY BETWEEN DATEADD(M, 6, @FY_START) AND DATEADD(M, 9, @FY_START) THEN 'Q3'
         WHEN @TODAY BETWEEN DATEADD(M, 9, @FY_START) AND DATEADD(M, 12, @FY_START) THEN 'Q4'
       END

beyond top level package error in relative import

Edit: 2020-05-08: Is seems the website I quoted is no longer controlled by the person who wrote the advice, so I'm removing the link to the site. Thanks for letting me know baxx.


If someone's still struggling a bit after the great answers already provided, I found advice on a website that no longer is available.

Essential quote from the site I mentioned:

"The same can be specified programmatically in this way:

import sys

sys.path.append('..')

Of course the code above must be written before the other import statement.

It's pretty obvious that it has to be this way, thinking on it after the fact. I was trying to use the sys.path.append('..') in my tests, but ran into the issue posted by OP. By adding the import and sys.path defintion before my other imports, I was able to solve the problem.

How do I connect to a specific Wi-Fi network in Android programmatically?

Before connecting WIFI network you need to check security type of the WIFI network ScanResult class has a capabilities. This field gives you type of network

Refer: https://developer.android.com/reference/android/net/wifi/ScanResult.html#capabilities

There are three types of WIFI networks.

First, instantiate a WifiConfiguration object and fill in the network’s SSID (note that it has to be enclosed in double quotes), set the initial state to disabled, and specify the network’s priority (numbers around 40 seem to work well).

WifiConfiguration wfc = new WifiConfiguration();

wfc.SSID = "\"".concat(ssid).concat("\"");
wfc.status = WifiConfiguration.Status.DISABLED;
wfc.priority = 40;

Now for the more complicated part: we need to fill several members of WifiConfiguration to specify the network’s security mode. For open networks.

wfc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
wfc.allowedProtocols.set(WifiConfiguration.Protocol.RSN);
wfc.allowedProtocols.set(WifiConfiguration.Protocol.WPA);
wfc.allowedAuthAlgorithms.clear();
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP104);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP);

For networks using WEP; note that the WEP key is also enclosed in double quotes.

wfc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
wfc.allowedProtocols.set(WifiConfiguration.Protocol.RSN);
wfc.allowedProtocols.set(WifiConfiguration.Protocol.WPA);
wfc.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN);
wfc.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.SHARED);
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP104);

if (isHexString(password)) wfc.wepKeys[0] = password;
else wfc.wepKeys[0] = "\"".concat(password).concat("\"");
wfc.wepTxKeyIndex = 0;

For networks using WPA and WPA2, we can set the same values for either.

wfc.allowedProtocols.set(WifiConfiguration.Protocol.RSN);
wfc.allowedProtocols.set(WifiConfiguration.Protocol.WPA);
wfc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK);
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
wfc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP40);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.WEP104);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP);
wfc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP);

wfc.preSharedKey = "\"".concat(password).concat("\"");

Finally, we can add the network to the WifiManager’s known list

WifiManager wfMgr = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
int networkId = wfMgr.addNetwork(wfc);
if (networkId != -1) {
 // success, can call wfMgr.enableNetwork(networkId, true) to connect
} 

How to return a dictionary | Python

I followed approach as shown in code below to return a dictionary. Created a class and declared dictionary as global and created a function to add value corresponding to some keys in dictionary.

**Note have used Python 2.7 so some minor modification might be required for Python 3+

class a:
    global d
    d={}
    def get_config(self,x):
        if x=='GENESYS':
            d['host'] = 'host name'
            d['port'] = '15222'
        return d

Calling get_config method using class instance in a separate python file:

from constant import a
class b:
    a().get_config('GENESYS')
    print a().get_config('GENESYS').get('host')
    print a().get_config('GENESYS').get('port')

Swift alert view with OK and Cancel: which button tapped?

If you are using iOS8, you should be using UIAlertController — UIAlertView is deprecated.

Here is an example of how to use it:

var refreshAlert = UIAlertController(title: "Refresh", message: "All data will be lost.", preferredStyle: UIAlertControllerStyle.Alert)

refreshAlert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: { (action: UIAlertAction!) in
  print("Handle Ok logic here")
  }))

refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { (action: UIAlertAction!) in
  print("Handle Cancel Logic here")
  }))

presentViewController(refreshAlert, animated: true, completion: nil)

As you can see the block handlers for the UIAlertAction handle the button presses. A great tutorial is here (although this tutorial is not written using swift): http://hayageek.com/uialertcontroller-example-ios/

Swift 3 update:

let refreshAlert = UIAlertController(title: "Refresh", message: "All data will be lost.", preferredStyle: UIAlertControllerStyle.alert)

refreshAlert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action: UIAlertAction!) in
    print("Handle Ok logic here")
}))

refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (action: UIAlertAction!) in
    print("Handle Cancel Logic here")
}))

present(refreshAlert, animated: true, completion: nil)

Swift 5 update:

let refreshAlert = UIAlertController(title: "Refresh", message: "All data will be lost.", preferredStyle: UIAlertControllerStyle.alert)

refreshAlert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action: UIAlertAction!) in
      print("Handle Ok logic here")
}))

refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (action: UIAlertAction!) in
      print("Handle Cancel Logic here")
}))

present(refreshAlert, animated: true, completion: nil)

Swift 5.3 update:

let refreshAlert = UIAlertController(title: "Refresh", message: "All data will be lost.", preferredStyle: UIAlertController.Style.alert)

refreshAlert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action: UIAlertAction!) in
      print("Handle Ok logic here")
}))

refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (action: UIAlertAction!) in
      print("Handle Cancel Logic here")
}))

present(refreshAlert, animated: true, completion: nil)

check the null terminating character in char*

You have used '/0' instead of '\0'. This is incorrect: the '\0' is a null character, while '/0' is a multicharacter literal.

Moreover, in C it is OK to skip a zero in your condition:

while (*(forward++)) {
    ...
}

is a valid way to check character, integer, pointer, etc. for being zero.

Check element CSS display with JavaScript

For jQuery, do you mean like this?

$('#object').css('display');

You can check it like this:

if($('#object').css('display') === 'block')
{
    //do something
}
else
{
    //something else
}

'module' object is not callable - calling method in another file

  • from a directory_of_modules, you can import a specific_module.py
  • this specific_module.py, can contain a Class with some_methods() or just functions()
  • from a specific_module.py, you can instantiate a Class or call functions()
  • from this Class, you can execute some_method()

Example:

#!/usr/bin/python3
from directory_of_modules import specific_module
instance = specific_module.DbConnect("username","password")
instance.login()

Excerpts from PEP 8 - Style Guide for Python Code:

Modules should have short and all-lowercase names.

Notice: Underscores can be used in the module name if it improves readability.

A Python module is simply a source file(*.py), which can expose:

  • Class: names using the "CapWords" convention.

  • Function: names in lowercase, words separated by underscores.

  • Global Variables: the conventions are about the same as those for Functions.

How to create empty constructor for data class in Kotlin Android

You have 2 options here:

  1. Assign a default value to each primary constructor parameter:

    data class Activity(
        var updated_on: String = "",
        var tags: List<String> = emptyList(),
        var description: String = "",
        var user_id: List<Int> = emptyList(),
        var status_id: Int = -1,
        var title: String = "",
        var created_at: String = "",
        var data: HashMap<*, *> = hashMapOf<Any, Any>(),
        var id: Int = -1,
        var counts: LinkedTreeMap<*, *> = LinkedTreeMap<Any, Any>()
    ) 
    
  2. Declare a secondary constructor that has no parameters:

    data class Activity(
        var updated_on: String,
        var tags: List<String>,
        var description: String,
        var user_id: List<Int>,
        var status_id: Int,
        var title: String,
        var created_at: String,
        var data: HashMap<*, *>,
        var id: Int,
        var counts: LinkedTreeMap<*, *>
    ) {
        constructor() : this("", emptyList(), 
                             "", emptyList(), -1, 
                             "", "", hashMapOf<Any, Any>(), 
                             -1, LinkedTreeMap<Any, Any>()
                             )
    }
    

If you don't rely on copy or equals of the Activity class or don't use the autogenerated data class methods at all you could use regular class like so:

class ActivityDto {
    var updated_on: String = "",
    var tags: List<String> = emptyList(),
    var description: String = "",
    var user_id: List<Int> = emptyList(),
    var status_id: Int = -1,
    var title: String = "",
    var created_at: String = "",
    var data: HashMap<*, *> = hashMapOf<Any, Any>(),
    var id: Int = -1,
    var counts: LinkedTreeMap<*, *> = LinkedTreeMap<Any, Any>()
}

Not every DTO needs to be a data class and vice versa. In fact in my experience I find data classes to be particularly useful in areas that involve some complex business logic.

Error while installing json gem 'mkmf.rb can't find header files for ruby'

You may need to install gcc after install ruby-devel

File content into unix variable with newlines

This is due to IFS (Internal Field Separator) variable which contains newline.

$ cat xx1
1
2

$ A=`cat xx1`
$ echo $A
1 2

$ echo "|$IFS|"
|       
|

A workaround is to reset IFS to not contain the newline, temporarily:

$ IFSBAK=$IFS
$ IFS=" "
$ A=`cat xx1` # Can use $() as well
$ echo $A
1
2
$ IFS=$IFSBAK

To REVERT this horrible change for IFS:

IFS=$IFSBAK

How do I convert a string to enum in TypeScript?

Enum

enum MyEnum {
    First,
    Second,
    Three
}

Sample usage

const parsed = Parser.parseEnum('FiRsT', MyEnum);
// parsed = MyEnum.First 

const parsedInvalid= Parser.parseEnum('other', MyEnum);
// parsedInvalid = undefined

Ignore case sensitive parse

class Parser {
    public static parseEnum<T>(value: string, enumType: T): T[keyof T] | undefined {
        if (!value) {
            return undefined;
        }

        for (const property in enumType) {
            const enumMember = enumType[property];
            if (typeof enumMember === 'string') {
                if (enumMember.toUpperCase() === value.toUpperCase()) {
                    const key = enumMember as string as keyof typeof enumType;
                    return enumType[key];
                }
            }
        }
        return undefined;
    }
}

WordPress is giving me 404 page not found for all pages except the homepage

You may have .htaccess disallowed in webhost settings. Setting to default permalinks would work in that case.

How to capture a backspace on the onkeydown event

In your function check for the keycode 8 (backspace) or 46 (delete)

Keycode information
Keycode list

MySQL Select Date Equal to Today

SELECT users.id, DATE_FORMAT(users.signup_date, '%Y-%m-%d') 
FROM users 
WHERE DATE(signup_date) = CURDATE()

Update style of a component onScroll in React.js

Update for an answer with React Hooks

These are two hooks - one for direction(up/down/none) and one for the actual position

Use like this:

useScrollPosition(position => {
    console.log(position)
  })

useScrollDirection(direction => {
    console.log(direction)
  })

Here are the hooks:

import { useState, useEffect } from "react"

export const SCROLL_DIRECTION_DOWN = "SCROLL_DIRECTION_DOWN"
export const SCROLL_DIRECTION_UP = "SCROLL_DIRECTION_UP"
export const SCROLL_DIRECTION_NONE = "SCROLL_DIRECTION_NONE"

export const useScrollDirection = callback => {
  const [lastYPosition, setLastYPosition] = useState(window.pageYOffset)
  const [timer, setTimer] = useState(null)

  const handleScroll = () => {
    if (timer !== null) {
      clearTimeout(timer)
    }
    setTimer(
      setTimeout(function () {
        callback(SCROLL_DIRECTION_NONE)
      }, 150)
    )
    if (window.pageYOffset === lastYPosition) return SCROLL_DIRECTION_NONE

    const direction = (() => {
      return lastYPosition < window.pageYOffset
        ? SCROLL_DIRECTION_DOWN
        : SCROLL_DIRECTION_UP
    })()

    callback(direction)
    setLastYPosition(window.pageYOffset)
  }

  useEffect(() => {
    window.addEventListener("scroll", handleScroll)
    return () => window.removeEventListener("scroll", handleScroll)
  })
}

export const useScrollPosition = callback => {
  const handleScroll = () => {
    callback(window.pageYOffset)
  }

  useEffect(() => {
    window.addEventListener("scroll", handleScroll)
    return () => window.removeEventListener("scroll", handleScroll)
  })
}

Adding quotes to a string in VBScript

You can do like:

a="""xyz"""  
g="abcd " & a  

Or:

a=chr(34) & "xyz" & chr(34)
g="abcd " & a  

Get full query string in C# ASP.NET

I have tested your example, and while Request.QueryString is not convertible to a string neither implicit nor explicit still the .ToString() method returns the correct result.

Further more when concatenating with a string using the "+" operator as in your example it will also return the correct result (because this behaves as if .ToString() was called).

As such there is nothing wrong with your code, and I would suggest that your issue was because of a typo in your code writing "Querystring" instead of "QueryString".

And this makes more sense with your error message since if the problem is that QueryString is a collection and not a string it would have to give another error message.

Java Long primitive type maximum limit

Long.MAX_VALUE is 9,223,372,036,854,775,807.

If you were executing your function once per nanosecond, it would still take over 292 years to encounter this situation according to this source.

When that happens, it'll just wrap around to Long.MIN_VALUE, or -9,223,372,036,854,775,808 as others have said.

Remove duplicates from a list of objects based on property in Java 8

Another solution is to use a Predicate, then you can use this in any filter:

public static <T> Predicate<T> distinctBy(Function<? super T, ?> f) {
  Set<Object> objects = new ConcurrentHashSet<>();
  return t -> objects.add(f.apply(t));
}

Then simply reuse the predicate anywhere:

employees.stream().filter(distinctBy(e -> e.getId));

Note: in the JavaDoc of filter, which says it takes a stateless Predicte. Actually, this works fine even if the stream is parallel.


About other solutions:

1) Using .collect(Collectors.toConcurrentMap(..)).values() is a good solution, but it's annoying if you want to sort and keep the order.

2) stream.removeIf(e->!seen.add(e.getID())); is also another very good solution. But we need to make sure the collection implemented removeIf, for example it will throw exception if we construct the collection use Arrays.asList(..).

How to display HTML <FORM> as inline element?

You can try this code:

<form action="#" method="get" id="login" style=" display:inline!important;">

  <label for='User'>User:</label> 
  <input type='text' name='User' id='User'>

  <label for='password'>Password:</label><input type='password' name='password' id='password'>
  <input type="submit" name="log" id="log" class="botton" value="Login" />

</form> 

The important thing to note is the css style property in the <form> tag.

display:inline!important;

Removing spaces from a variable input using PowerShell 4.0

You can use:

$answer.replace(' ' , '')

or

$answer -replace " ", ""

if you want to remove all whitespace you can use:

$answer -replace "\s", ""

How to pass arguments to a Dockerfile?

You are looking for --build-arg and the ARG instruction. These are new as of Docker 1.9. Check out https://docs.docker.com/engine/reference/builder/#arg. This will allow you to add ARG arg to the Dockerfile and then build with docker build --build-arg arg=2.3 ..

Calling one method from another within same class in Python

To call the method, you need to qualify function with self.. In addition to that, if you want to pass a filename, add a filename parameter (or other name you want).

class MyHandler(FileSystemEventHandler):

    def on_any_event(self, event):
        srcpath = event.src_path
        print (srcpath, 'has been ',event.event_type)
        print (datetime.datetime.now())
        filename = srcpath[12:]
        self.dropbox_fn(filename) # <----

    def dropbox_fn(self, filename):  # <-----
        print('In dropbox_fn:', filename)

What are the proper permissions for an upload folder with PHP/Apache?

I would go with Ryan's answer if you really want to do this.

In general on a *nix environment, you always want to err on giving away as little permissions as possible.

9 times out of 10, 755 is the ideal permission for this - as the only user with the ability to modify the files will be the webserver. Change this to 775 with your ftp user in a group if you REALLY need to change this.

Since you're new to php by your own admission, here's a helpful link for improving the security of your upload service: move_uploaded_file

SSIS cannot convert because a potential loss of data

For me just removed the OLE DB source from SSIS and added again. Worked!

Convert to/from DateTime and Time in Ruby

Improving on Gordon Wilson solution, here is my try:

def to_time
  #Convert a fraction of a day to a number of microseconds
  usec = (sec_fraction * 60 * 60 * 24 * (10**6)).to_i
  t = Time.gm(year, month, day, hour, min, sec, usec)
  t - offset.abs.div(SECONDS_IN_DAY)
end

You'll get the same time in UTC, loosing the timezone (unfortunately)

Also, if you have ruby 1.9, just try the to_time method

How to resolve the error "Unable to access jarfile ApacheJMeter.jar errorlevel=1" while initiating Jmeter?

I faced with the same error, when i downloaded the Jmeter Source, and it got fixed once i downloaded Jmeter Binary. Please watch this video.

'xmlParseEntityRef: no name' warnings while loading xml into a php file

The XML is most probably invalid.

The problem could be the "&"

$text=preg_replace('/&(?!#?[a-z0-9]+;)/', '&amp;', $text);

will get rid of the "&" and replace it with it's HTML code version...give it a try.

Number of elements in a javascript object

AFAIK, there is no way to do this reliably, unless you switch to an array. Which honestly, doesn't seem strange - it's seems pretty straight forward to me that arrays are countable, and objects aren't.

Probably the closest you'll get is something like this

// Monkey patching on purpose to make a point
Object.prototype.length = function()
{
  var i = 0;
  for ( var p in this ) i++;
  return i;
}

alert( {foo:"bar", bar: "baz"}.length() ); // alerts 3

But this creates problems, or at least questions. All user-created properties are counted, including the _length function itself! And while in this simple example you could avoid it by just using a normal function, that doesn't mean you can stop other scripts from doing this. so what do you do? Ignore function properties?

Object.prototype.length = function()
{
  var i = 0;
  for ( var p in this )
  {
      if ( 'function' == typeof this[p] ) continue;
      i++;
  }
  return i;
}

alert( {foo:"bar", bar: "baz"}.length() ); // alerts 2

In the end, I think you should probably ditch the idea of making your objects countable and figure out another way to do whatever it is you're doing.

How can we store into an NSDictionary? What is the difference between NSDictionary and NSMutableDictionary?

The key difference: NSMutableDictionary can be modified in place, NSDictionary cannot. This is true for all the other NSMutable* classes in Cocoa. NSMutableDictionary is a subclass of NSDictionary, so everything you can do with NSDictionary you can do with both. However, NSMutableDictionary also adds complementary methods to modify things in place, such as the method setObject:forKey:.

You can convert between the two like this:

NSMutableDictionary *mutable = [[dict mutableCopy] autorelease];
NSDictionary *dict = [[mutable copy] autorelease]; 

Presumably you want to store data by writing it to a file. NSDictionary has a method to do this (which also works with NSMutableDictionary):

BOOL success = [dict writeToFile:@"/file/path" atomically:YES];

To read a dictionary from a file, there's a corresponding method:

NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:@"/file/path"];

If you want to read the file as an NSMutableDictionary, simply use:

NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithContentsOfFile:@"/file/path"];

read file in classpath

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class readFile {
    /**
     * feel free to make any modification I have have been here so I feel you
     * 
     * @param args
     * @throws InterruptedException
     */
    public static void main(String[] args) throws InterruptedException {
        File dir = new File(".");// read file from same directory as source //
        if (dir.isDirectory()) {
            File[] files = dir.listFiles();
            for (File file : files) {
                // if you wanna read file name with txt files
                if (file.getName().contains("txt")) {
                    System.out.println(file.getName());
                }

                // if you want to open text file and read each line then
                if (file.getName().contains("txt")) {
                    try {
                        // FileReader reads text files in the default encoding.
                        FileReader fileReader = new FileReader(
                                file.getAbsolutePath());
                        // Always wrap FileReader in BufferedReader.
                        BufferedReader bufferedReader = new BufferedReader(
                                fileReader);
                        String line;
                        // get file details and get info you need.
                        while ((line = bufferedReader.readLine()) != null) {
                            System.out.println(line);
                            // here you can say...
                            // System.out.println(line.substring(0, 10)); this
                            // prints from 0 to 10 indext
                        }
                    } catch (FileNotFoundException ex) {
                        System.out.println("Unable to open file '"
                                + file.getName() + "'");
                    } catch (IOException ex) {
                        System.out.println("Error reading file '"
                                + file.getName() + "'");
                        // Or we could just do this:
                        ex.printStackTrace();
                    }
                }
            }
        }

    }`enter code here`

}

How would I find the second largest salary from the employee table?

Simple Answer:

SELECT distinct(sal)
FROM emp
ORDER BY sal DESC
LIMIT 1, 1;

You will get only the second max salary.

And if you need any 3rd or 4th or Nth value you can increase the first value followed by LIMIT (n-1) ie. for 4th salary : LIMIT 3, 1;

How does jQuery work when there are multiple elements with the same ID value?

From the id Selector jQuery page:

Each id value must be used only once within a document. If more than one element has been assigned the same ID, queries that use that ID will only select the first matched element in the DOM. This behavior should not be relied on, however; a document with more than one element using the same ID is invalid.

Naughty Google. But they don't even close their <html> and <body> tags I hear. The question is though, why Misha's 2nd and 3rd queries return 2 and not 1 as well.

How to delete the first row of a dataframe in R?

Keep the labels from your original file like this:

df = read.table('data.txt', header = T)

If you have columns named x and y, you can address them like this:

df$x
df$y

If you'd like to actually delete the first row from a data.frame, you can use negative indices like this:

df = df[-1,]

If you'd like to delete a column from a data.frame, you can assign NULL to it:

df$x = NULL

Here are some simple examples of how to create and manipulate a data.frame in R:

# create a data.frame with 10 rows
> x = rnorm(10)
> y = runif(10)
> df = data.frame( x, y )

# write it to a file
> write.table( df, 'test.txt', row.names = F, quote = F )

# read a data.frame from a file: 
> read.table( df, 'test.txt', header = T )

> df$x
 [1] -0.95343778 -0.63098637 -1.30646529  1.38906143  0.51703237 -0.02246754
 [7]  0.20583548  0.21530721  0.69087460  2.30610998
> df$y
 [1] 0.66658148 0.15355851 0.60098886 0.14284576 0.20408723 0.58271061
 [7] 0.05170994 0.83627336 0.76713317 0.95052671

> df$x = x
> df
            y           x
1  0.66658148 -0.95343778
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df[-1,]
            y           x
2  0.15355851 -0.63098637
3  0.60098886 -1.30646529
4  0.14284576  1.38906143
5  0.20408723  0.51703237
6  0.58271061 -0.02246754
7  0.05170994  0.20583548
8  0.83627336  0.21530721
9  0.76713317  0.69087460
10 0.95052671  2.30610998

> df$x = NULL
> df 
            y
1  0.66658148
2  0.15355851
3  0.60098886
4  0.14284576
5  0.20408723
6  0.58271061
7  0.05170994
8  0.83627336
9  0.76713317
10 0.95052671

Decoding JSON String in Java

Well your jsonString is wrong.

String jsonString = "{\"stat\":{\"sdr\": \"aa:bb:cc:dd:ee:ff\",\"rcv\": \"aa:bb:cc:dd:ee:ff\",\"time\": \"UTC in millis\",\"type\": 1,\"subt\": 1,\"argv\": [{\"1\":2},{\"2\":3}]}}";

use this jsonString and if you use the same JSONParser and ContainerFactory in the example you will see that it will be encoded/decoded.

Additionally if you want to print your string after stat here it goes:

     try{
        Map json = (Map)parser.parse(jsonString, containerFactory);
        Iterator iter = json.entrySet().iterator();
        System.out.println("==iterate result==");
        Object entry = json.get("stat");
        System.out.println(entry);
      }

And about the json libraries, there are a lot of them. Better you check this.

Unable to simultaneously satisfy constraints, will attempt to recover by breaking constraint

I am getting this same error, but only on a specific view, when I touch the first textfield, and then the next textfield down.

I am writing in SwiftUI for iOS 13.4

 Unable to simultaneously satisfy constraints.
        Probably at least one of the constraints in the following list is one you don't want. 
        Try this: 
            (1) look at each constraint and try to figure out which you don't expect; 
            (2) find the code that added the unwanted constraint or constraints and fix it. 
    (
        "<NSLayoutConstraint:0x2809b6760 'assistantHeight' TUISystemInputAssistantView:0x105710da0.height == 44   (active)>",
        "<NSLayoutConstraint:0x2809ccff0 'assistantView.bottom' TUISystemInputAssistantView:0x105710da0.bottom == _UIKBCompatInputView:0x10525ae10.top   (active)>",
        "<NSLayoutConstraint:0x2809cccd0 'assistantView.top' V:|-(0)-[TUISystemInputAssistantView:0x105710da0]   (active, names: '|':UIInputSetHostView:0x105215010 )>",
        "<NSLayoutConstraint:0x2809ca300 'inputView.top' V:|-(0)-[_UIKBCompatInputView:0x10525ae10]   (active, names: '|':UIInputSetHostView:0x105215010 )>"
    )

    Will attempt to recover by breaking constraint 
    <NSLayoutConstraint:0x2809ccff0 'assistantView.bottom' TUISystemInputAssistantView:0x105710da0.bottom == _UIKBCompatInputView:0x10525ae10.top   (active)>

    Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
    The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.

Remove a HTML tag but keep the innerHtml

Another native solution (in coffee):

el = document.getElementsByTagName 'b'

docFrag = document.createDocumentFragment()
docFrag.appendChild el.firstChild while el.childNodes.length

el.parentNode.replaceChild docFrag, el

I don't know if it's faster than user113716's solution, but it might be easier to understand for some.

How to scroll UITableView to specific position

Use [tableView scrollToRowAtIndexPath:indexPath atScrollPosition:scrollPosition animated:YES]; Scrolls the receiver until a row identified by index path is at a particular location on the screen.

And

scrollToNearestSelectedRowAtScrollPosition:animated:

Scrolls the table view so that the selected row nearest to a specified position in the table view is at that position.

What is [Serializable] and when should I use it?

What is it?

When you create an object in a .Net framework application, you don't need to think about how the data is stored in memory. Because the .Net Framework takes care of that for you. However, if you want to store the contents of an object to a file, send an object to another process or transmit it across the network, you do have to think about how the object is represented because you will need to convert to a different format. This conversion is called SERIALIZATION.

Uses for Serialization

Serialization allows the developer to save the state of an object and recreate it as needed, providing storage of objects as well as data exchange. Through serialization, a developer can perform actions like sending the object to a remote application by means of a Web Service, passing an object from one domain to another, passing an object through a firewall as an XML string, or maintaining security or user-specific information across applications.

Apply SerializableAttribute to a type to indicate that instances of this type can be serialized. Apply the SerializableAttribute even if the class also implements the ISerializable interface to control the serialization process.

All the public and private fields in a type that are marked by the SerializableAttribute are serialized by default, unless the type implements the ISerializable interface to override the serialization process. The default serialization process excludes fields that are marked with NonSerializedAttribute. If a field of a serializable type contains a pointer, a handle, or some other data structure that is specific to a particular environment, and cannot be meaningfully reconstituted in a different environment, then you might want to apply NonSerializedAttribute to that field.

See MSDN for more details.

Edit 1

Any reason to not mark something as serializable

When transferring or saving data, you need to send or save only the required data. So there will be less transfer delays and storage issues. So you can opt out unnecessary chunk of data when serializing.

how to compare the Java Byte[] array?

If you're trying to use the array as a generic HashMap key, that's not going to work. Consider creating a custom wrapper object that holds the array, and whose equals(...) and hashcode(...) method returns the results from the java.util.Arrays methods. For example...

import java.util.Arrays;

public class MyByteArray {
   private byte[] data;

   // ... constructors, getters methods, setter methods, etc...


   @Override
   public int hashCode() {
      return Arrays.hashCode(data);
   }

   @Override
   public boolean equals(Object obj) {
      if (this == obj)
         return true;
      if (obj == null)
         return false;
      if (getClass() != obj.getClass())
         return false;
      MyByteArray other = (MyByteArray) obj;
      if (!Arrays.equals(data, other.data))
         return false;
      return true;
   }


}

Objects of this wrapper class will work fine as a key for your HashMap<MyByteArray, OtherType> and will allow for clean use of equals(...) and hashCode(...) methods.

SimpleXML - I/O warning : failed to load external entity

You can also load the content with cURL, if file_get_contents insn't enabled on your server.

Example:

$ch = curl_init();  

curl_setopt($ch,CURLOPT_URL,"http://feeds.bbci.co.uk/sport/0/football/rss.xml?edition=int");
curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);

$output = curl_exec($ch);

curl_close($ch);

$items = simplexml_load_string($output);

Calculating arithmetic mean (one type of average) in Python

You don't even need numpy or scipy...

>>> a = [1, 2, 3, 4, 5, 6]
>>> print(sum(a) / len(a))
3

Format an Integer using Java String Format

Use %03d in the format specifier for the integer. The 0 means that the number will be zero-filled if it is less than three (in this case) digits.

See the Formatter docs for other modifiers.

How to use a variable for a key in a JavaScript object literal?

Given code:

var thetop = 'top';
<something>.stop().animate(
    { thetop : 10 }, 10
);

Translation:

var thetop = 'top';
var config = { thetop : 10 }; // config.thetop = 10
<something>.stop().animate(config, 10);

As you can see, the { thetop : 10 } declaration doesn't make use of the variable thetop. Instead it creates an object with a key named thetop. If you want the key to be the value of the variable thetop, then you will have to use square brackets around thetop:

var thetop = 'top';
var config = { [thetop] : 10 }; // config.top = 10
<something>.stop().animate(config, 10);

The square bracket syntax has been introduced with ES6. In earlier versions of JavaScript, you would have to do the following:

var thetop = 'top';
var config = (
  obj = {},
  obj['' + thetop] = 10,
  obj
); // config.top = 10
<something>.stop().animate(config, 10);

This action could not be completed. Try Again (-22421)

Tested in Xcode 7.3, 04142016

Instead of clicking the blue Upload to App Store… button from the Organizer or while Archiving, Xcode offers a better tool to do this, but it is a little hidden and the process is not clear how to use it.

Here is what I documented while submitting our latest iOS application to the App Store:

First, do NOT use the blue Upload to App Store… button.

From Xcode's Xcode: Developer Tools: menu, select Application Loader.

Sign in with appropriate credentials that allow you to upload to the App Store.

When Application Loader shows you its main screen, select the Choose button on the lower right of the main window and open your IPA that you exported for the App Store.

Proceed with the submission.

Why you want to do this:

  1. Detailed app submission error reporting. Exact explanations of submission errors. It tells you what's incorrect in your app that you are trying to submit.
  2. You don't have to deal with the insipid error that prompted this question in the first place.
  3. It works consistently in my tests where Xcode's Submit App to Store… from the Archive menu does not.

sql delete statement where date is greater than 30 days

You could also use

SELECT * from Results WHERE date < NOW() - INTERVAL 30 DAY;

Oracle "ORA-01008: not all variables bound" Error w/ Parameters

It seems daft, but I think when you use the same bind variable twice you have to set it twice:

cmd.Parameters.Add("VarA", "24");
cmd.Parameters.Add("VarB", "test");
cmd.Parameters.Add("VarB", "test");
cmd.Parameters.Add("VarC", "1234");
cmd.Parameters.Add("VarC", "1234");

Certainly that's true with Native Dynamic SQL in PL/SQL:

SQL> begin
  2     execute immediate 'select * from emp where ename=:name and ename=:name'
  3     using 'KING';
  4  end;
  5  /
begin
*
ERROR at line 1:
ORA-01008: not all variables bound


SQL> begin
  2     execute immediate 'select * from emp where ename=:name and ename=:name' 
  3     using 'KING', 'KING';
  4  end;
  5  /

PL/SQL procedure successfully completed.

jQuery: Uncheck other checkbox on one checked

$('.cw2').change(function () {
    if ($('input.cw2').filter(':checked').length >= 1) {
        $('input.cw2').not(this).prop('checked', false);
    } 
});


$('td, input').prop(function (){
    $(this).css({ 'background-color': '#DFD8D1' });
    $(this).addClass('changed');
});

What is the different between RESTful and RESTless

Any model which don't identify resource and the action associated with is restless. restless is not any term but a slang term to represent all other services that doesn't abide with the above definition. In restful model resource is identified by URL (NOUN) and the actions(VERBS) by the predefined methods in HTTP protocols i.e. GET, POST, PUT, DELETE etc.

How to append the output to a file?

you can append the file with >> sign. It insert the contents at the last of the file which we are using.e.g if file let its name is myfile contains xyz then cat >> myfile abc ctrl d

after the above process the myfile contains xyzabc.

How to get the function name from within that function?

You can use constructor name like:

{your_function}.prototype.constructor.name

this code simply return name of a method.

Fix footer to bottom of page

We can use FlexBox for Sticky Footer and Header without using POSITIONS in CSS.

_x000D_
_x000D_
.container {_x000D_
  display: flex;_x000D_
  flex-direction: column;_x000D_
  height: 100vh;_x000D_
}_x000D_
_x000D_
header {_x000D_
  height: 50px;_x000D_
  flex-shrink: 0;_x000D_
  background-color: #037cf5;_x000D_
}_x000D_
_x000D_
footer {_x000D_
  height: 50px;_x000D_
  flex-shrink: 0;_x000D_
  background-color: #134c7d;_x000D_
}_x000D_
_x000D_
main {_x000D_
  flex: 1 0 auto;_x000D_
}
_x000D_
<div class="container">_x000D_
  <header>HEADER</header>_x000D_
  <main class="content">_x000D_
_x000D_
  </main>_x000D_
  <footer>FOOTER</footer>_x000D_
</div>
_x000D_
_x000D_
_x000D_

DEMO - JSFiddle

Note : Check browser supports for FlexBox. caniuse

How to enable remote access of mysql in centos?

Bind-address XXX.XX.XX.XXX in /etc/my.cnf

comment line:

skip-networking

or

skip-external-locking

after edit hit service mysqld restart

login into mysql and hit this query:

GRANT ALL PRIVILEGES ON dbname.* TO 'username'@'%' IDENTIFIED BY 'password';

FLUSH PRIVILEGES;
quit;

add firewall rule:

iptables -I INPUT -i eth0 -p tcp --destination-port 3306 -j ACCEPT

C# equivalent of the IsNull() function in SQL Server

You Write Two Function

    //When Expression is Number
    public static double? isNull(double? Expression, double? Value)
    {
        if (Expression ==null)
        {
            return Value;
        }
        else
        {
            return Expression;
        }
    }


    //When Expression is string (Can not send Null value in string Expression
    public static string isEmpty(string Expression, string Value)
    {
        if (Expression == "")
        {
            return Value;
        }
        else
        {
            return Expression;
        }
    }

They Work Very Well

Generating a WSDL from an XSD file

we can generate wsdl file from xsd but you have to use oracle enterprise pack of eclipse(OEPE). simply create xsd and then right click->new->wsdl...

If...Then...Else with multiple statements after Then

This works with multiple statements:

if condition1 Then stmt1:stmt2 Else if condition2 Then stmt3:stmt4 Else stmt5:stmt6

Or you can split it over multiple lines:

if condition1 Then stmt1:stmt2
Else if condition2 Then stmt3:stmt4
Else stmt5:stmt6

Android REST client, Sample?

There is plenty of libraries out there and I'm using this one: https://github.com/nerde/rest-resource. This was created by me, and, as you can see in the documentation, it's way cleaner and simpler than the other ones. It's not focused on Android, but I'm using in it and it's working pretty well.

It supports HTTP Basic Auth. It does the dirty job of serializing and deserializing JSON objects. You will like it, specially if your API is Rails like.

MVC ajax post to controller action method

$('#loginBtn').click(function(e) {
    e.preventDefault(); /// it should not have this code or else it wont continue
    //....
});

How to fit a smooth curve to my data in R?

I like loess() a lot for smoothing:

x <- 1:10
y <- c(2,4,6,8,7,12,14,16,18,20)
lo <- loess(y~x)
plot(x,y)
lines(predict(lo), col='red', lwd=2)

Venables and Ripley's MASS book has an entire section on smoothing that also covers splines and polynomials -- but loess() is just about everybody's favourite.

Python element-wise tuple operations like sum

Sort of combined the first two answers, with a tweak to ironfroggy's code so that it returns a tuple:

import operator

class stuple(tuple):
    def __add__(self, other):
        return self.__class__(map(operator.add, self, other))
        # obviously leaving out checking lengths

>>> a = stuple([1,2,3])
>>> b = stuple([3,2,1])
>>> a + b
(4, 4, 4)

Note: using self.__class__ instead of stuple to ease subclassing.

how to kill the tty in unix

If you want to close tty for specific user with all the process, above command is the easiest. You can use:

killall -u user_name

How to concatenate two strings in C++?

It is better to use C++ string class instead of old style C string, life would be much easier.

if you have existing old style string, you can covert to string class

    char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
    cout<<greeting + "and there \n"; //will not compile because concat does \n not work on old C style string
    string trueString = string (greeting);
    cout << trueString + "and there \n"; // compiles fine
    cout << trueString + 'c'; // this will be fine too. if one of the operand if C++ string, this will work too

Tests not running in Test Explorer

For me having a property called TestContext in a base class was causing this behavior. For example:

[TestClass]
public abstract class TestClassBase
{
    protected object TestContext { get; private set; }
}

[TestClass]
public class TestClass : TestClassBase
{
    // This method not found
    [TestMethod]
    public void TestCase() {}
}

MySQL direct INSERT INTO with WHERE clause

you can use UPDATE command.

UPDATE table_name SET name=@name, email=@email, phone=@phone WHERE client_id=@client_id

Sort Go map values by keys

All of the answers here now contain the old behavior of maps. In Go 1.12+, you can just print a map value and it will be sorted by key automatically. This has been added because it allows the testing of map values easily.

func main() {
    m := map[int]int{3: 5, 2: 4, 1: 3}
    fmt.Println(m)

    // In Go 1.12+
    // Output: map[1:3 2:4 3:5]

    // Before Go 1.12 (the order was undefined)
    // map[3:5 2:4 1:3]
}

Maps are now printed in key-sorted order to ease testing. The ordering rules are:

  • When applicable, nil compares low
  • ints, floats, and strings order by <
  • NaN compares less than non-NaN floats
  • bool compares false before true
  • Complex compares real, then imaginary
  • Pointers compare by machine address
  • Channel values compare by machine address
  • Structs compare each field in turn
  • Arrays compare each element in turn
  • Interface values compare first by reflect.Type describing the concrete type and then by concrete value as described in the previous rules.

When printing maps, non-reflexive key values like NaN were previously displayed as <nil>. As of this release, the correct values are printed.

Read more here.

How to access form methods and controls from a class in C#?

You are trying to access the class as opposed to the object. That statement can be confusing to beginners, but you are effectively trying to open your house door by picking up the door on your house plans.

If you actually wanted to access the form components directly from a class (which you don't) you would use the variable that instantiates your form.

Depending on which way you want to go you'd be better of either sending the text of a control or whatever to a method in your classes eg

public void DoSomethingWithText(string formText)
{
   // do something text in here
}

or exposing properties on your form class and setting the form text in there - eg

string SomeProperty
{
   get 
   {
      return textBox1.Text;
   }
   set
   {
      textBox1.Text = value;
   }
}

ssh: The authenticity of host 'hostname' can't be established

Add these to your /etc/ssh/ssh_config

Host *
UserKnownHostsFile=/dev/null
StrictHostKeyChecking=no

npm notice created a lockfile as package-lock.json. You should commit this file

You can update the existing package-lock.json file instead of creating a new one. Just change the version number to a different one.

{ "name": "theme","version": "1.0.1", "description": "theme description"}

simple Jquery hover enlarge

Well I'm not exactly sure why your code is not working because I usually follow a different approach when trying to accomplish something similar.

But your code is erroring out.. There seems to be an issue with the way you are using scale I got the jQuery to actually execute by changing your code to the following.

$(document).ready(function(){
    $('img').hover(function() {
        $(this).css("cursor", "pointer");
        $(this).toggle({
          effect: "scale",
          percent: "90%"
        },200);
    }, function() {
         $(this).toggle({
           effect: "scale",
           percent: "80%"
         },200);

    });
});  

But I have always done it by using CSS to setup my scaling and transition..

Here is an example, hopefully it helps.

$(document).ready(function(){
    $('#content').hover(function() {
        $("#content").addClass('transition');

    }, function() {
        $("#content").removeClass('transition');
    });
});

http://jsfiddle.net/y4yAP/

How to format an inline code in Confluence?

By default Confluence renders monospaced text with transparent background. You can edit global CSS to add grey color. From Confluence manual:

  1. Choose the cog icon at top right of the screen, then choose Confluence Admin.
  2. Choose Stylesheet.
  3. Choose Edit.
  4. Paste your custom CSS into the text field.
  5. Choose Save.

Custom CSS for displaying grey background in monospaced blocks:

code {
    padding: 1px 5px 1px 5px; 
    font-family: Consolas, Menlo, Monaco, Lucida Console, Liberation Mono, DejaVu Sans Mono, Bitstream Vera Sans Mono, Courier New, monospace, serif;
    background-color: #eeeeee;
}

If you're using Confluence OnDemand (cloud):

  1. Click the cog/gear in the bottom of the sidebar on the left
  2. Select Look and Feel
  3. Click the Sidebar, Header and Footer tab
  4. Paste your custom CSS into the Header field
  5. Wrap the code in a {style} block
  6. Save

Paste the following:

{style}
code {
    padding: 1px 5px 1px 5px; 
    font-family: Consolas, Menlo, Monaco, Lucida Console, Liberation Mono, DejaVu Sans Mono, Bitstream Vera Sans Mono, Courier New, monospace, serif;
    background-color: #eeeeee;
}
{style}

After that you'll get nice and tidy stackoverflow-stylish inline code spans just by writing {{sometext}}.

XAMPP Start automatically on Windows 7 startup

I am using XAMPP on Win 7 and 8.1 too...it start normally.

Did you try to check the services on Start > RUN > services.msc

Find the service: Apache 2.x. (right click) choose Properties. At form "Startup type" choose "Automatically" and Start the service on.

you should reset the PC and check out again.

Do the same with mySQL.

If you can not solve the problem, use XAMPP Panel to start it manually.

How to make php display \t \n as tab and new line instead of characters

Put it in double quotes:

echo "\t";

Single quotes do not expand escaped characters.

Use the documentation when in doubt.

How to increase font size in the Xcode editor?

You can use this plugin to change the font size using ? + or ? - (Control - and Control + in the latest versions of Xcode. The plugin developers changed the shortcut to avoid conflict with Interface Builder hotkeys):

https://github.com/zats/AdjustFontSize-Xcode-Plugin

Pass Model To Controller using Jquery/Ajax

Use the following JS:

$(document).ready(function () {
    $("#btnsubmit").click(function () {

             $.ajax({
                 type: "POST",
                 url: '/Plan/PlanManage',     //your action
                 data: $('#PlanForm').serialize(),   //your form name.it takes all the values of model               
                 dataType: 'json',
                 success: function (result) {
                     console.log(result);
                 }
             })
        return false;
    });
});

and the following code on your controller:

[HttpPost]
public string PlanManage(Plan objplan)  //model plan
{
}

How many parameters are too many?

I'd say as long as you have overloads that have 2-4 than you're good to go up higher if you need it.

NLTK and Stopwords Fail #lookuperror

import nltk

nltk.download()

  • A GUI pops up and in that go the Corpora section, select the required corpus.
  • Verified Result

Java Programming: call an exe from Java and passing parameters

You're on the right track. The two constructors accept arguments, or you can specify them post-construction with ProcessBuilder#command(java.util.List) and ProcessBuilder#command(String...).

Inject service in app.config

I don't think you're supposed to be able to do this, but I have successfully injected a service into a config block. (AngularJS v1.0.7)

angular.module('dogmaService', [])
    .factory('dogmaCacheBuster', [
        function() {
            return function(path) {
                return path + '?_=' + Date.now();
            };
        }
    ]);

angular.module('touch', [
        'dogmaForm',
        'dogmaValidate',
        'dogmaPresentation',
        'dogmaController',
        'dogmaService',
    ])
    .config([
        '$routeProvider',
        'dogmaCacheBusterProvider',
        function($routeProvider, cacheBuster) {
            var bust = cacheBuster.$get[0]();

            $routeProvider
                .when('/', {
                    templateUrl: bust('touch/customer'),
                    controller: 'CustomerCtrl'
                })
                .when('/screen2', {
                    templateUrl: bust('touch/screen2'),
                    controller: 'Screen2Ctrl'
                })
                .otherwise({
                    redirectTo: bust('/')
                });
        }
    ]);

angular.module('dogmaController', [])
    .controller('CustomerCtrl', [
        '$scope',
        '$http',
        '$location',
        'dogmaCacheBuster',
        function($scope, $http, $location, cacheBuster) {

            $scope.submit = function() {
                $.ajax({
                    url: cacheBuster('/customers'),  //server script to process data
                    type: 'POST',
                    //Ajax events
                    // Form data
                    data: formData,
                    //Options to tell JQuery not to process data or worry about content-type
                    cache: false,
                    contentType: false,
                    processData: false,
                    success: function() {
                        $location
                            .path('/screen2');

                        $scope.$$phase || $scope.$apply();
                    }
                });
            };
        }
    ]);

jquery function val() is not equivalent to "$(this).value="?

You want:

this.value = ''; // straight JS, no jQuery

or

$(this).val(''); // jQuery

With $(this).value = '' you're assigning an empty string as the value property of the jQuery object that wraps this -- not the value of this itself.

Insert if not exists Oracle

Coming late to the party, but...

With oracle 11.2.0.1 there is a semantic hint that can do this: IGNORE_ROW_ON_DUPKEY_INDEX

Example:

insert /*+ IGNORE_ROW_ON_DUPKEY_INDEX(customer_orders,pk_customer_orders) */
  into customer_orders
       (order_id, customer, product)
values (    1234,     9876,  'K598')
     ;

UPDATE: Although this hint works (if you spell it correctly), there are better approaches which don't require Oracle 11R2:

First approach—direct translation of above semantic hint:

begin
  insert into customer_orders
         (order_id, customer, product)
  values (    1234,     9876,  'K698')
  ;
  commit;
exception
  when DUP_VAL_ON_INDEX
  then ROLLBACK;
end;

Second aproach—a lot faster than both above hints when there's a lot of contention:

begin
    select count (*)
    into   l_is_matching_row
    from   customer_orders
    where  order_id = 1234
    ;

    if (l_is_matching_row = 0)
    then
      insert into customer_orders
             (order_id, customer, product)
      values (    1234,     9876,  'K698')
      ;
      commit;
    end if;
exception
  when DUP_VAL_ON_INDEX
  then ROLLBACK;
end;

Error:attempt to apply non-function

I got the error because of a clumsy typo:

This errors:

knitr::opts_chunk$seet(echo = FALSE)

Error: attempt to apply non-function

After correcting the typo, it works:

knitr::opts_chunk$set(echo = FALSE)

This Handler class should be static or leaks might occur: IncomingHandler

Here is a generic example of using a weak reference and static handler class to resolve the problem (as recommended in the Lint documentation):

public class MyClass{

  //static inner class doesn't hold an implicit reference to the outer class
  private static class MyHandler extends Handler {
    //Using a weak reference means you won't prevent garbage collection
    private final WeakReference<MyClass> myClassWeakReference; 

    public MyHandler(MyClass myClassInstance) {
      myClassWeakReference = new WeakReference<MyClass>(myClassInstance);
    }

    @Override
    public void handleMessage(Message msg) {
      MyClass myClass = myClassWeakReference.get();
      if (myClass != null) {
        ...do work here...
      }
    }
  }

  /**
   * An example getter to provide it to some external class
   * or just use 'new MyHandler(this)' if you are using it internally.
   * If you only use it internally you might even want it as final member:
   * private final MyHandler mHandler = new MyHandler(this);
   */
  public Handler getHandler() {
    return new MyHandler(this);
  }
}

How to change Android usb connect mode to charge only?

Nothing worked until I went this way: Settings>Developer options>Default USB configuration now you can choose your default USB connection purpose.

How to upload a file in Django?

Not sure if there any disadvantages to this approach but even more minimal, in views.py:

entry = form.save()

# save uploaded file
if request.FILES['myfile']:
    entry.myfile.save(request.FILES['myfile']._name, request.FILES['myfile'], True)

How can I use break or continue within for loop in Twig template?

From docs TWIG docs:

Unlike in PHP, it's not possible to break or continue in a loop.

But still:

You can however filter the sequence during iteration which allows you to skip items.

Example 1 (for huge lists you can filter posts using slice, slice(start, length)):

{% for post in posts|slice(0,10) %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

Example 2:

{% for post in posts if post.id < 10 %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

You can even use own TWIG filters for more complexed conditions, like:

{% for post in posts|onlySuperPosts %}
    <h2>{{ post.heading }}</h2>
{% endfor %}

How to convert 1 to true or 0 to false upon model fetch

Here's another option that's longer but may be more readable:

Boolean(Number("0")); // false
Boolean(Number("1")); // true

What is the difference between tinyint, smallint, mediumint, bigint and int in MySQL?

The difference is the amount of memory allocated to each integer, and how large a number they each can store.

Package name does not correspond to the file path - IntelliJ

You should declare in the Project structure(Ctrl+Alt+Shift+s) in the Module section mark your folders which of them are source package(blue one) and which are test ...

Time in milliseconds in C

You can use gettimeofday() together with the timedifference_msec() function below to calculate the number of milliseconds elapsed between two samples:

#include <sys/time.h>
#include <stdio.h>

float timedifference_msec(struct timeval t0, struct timeval t1)
{
    return (t1.tv_sec - t0.tv_sec) * 1000.0f + (t1.tv_usec - t0.tv_usec) / 1000.0f;
}

int main(void)
{
   struct timeval t0;
   struct timeval t1;
   float elapsed;

   gettimeofday(&t0, 0);
   /* ... YOUR CODE HERE ... */
   gettimeofday(&t1, 0);

   elapsed = timedifference_msec(t0, t1);

   printf("Code executed in %f milliseconds.\n", elapsed);

   return 0;
}

Note that, when using gettimeofday(), you need to take seconds into account even if you only care about microsecond differences because tv_usec will wrap back to zero every second and you have no way of knowing beforehand at which point within a second each sample is obtained.

Is there a way to only install the mysql client (Linux)?

[root@localhost administrador]# yum search mysql | grep client
community-mysql.i686 : MySQL client programs and shared libraries
                            : client
community-mysql-libs.i686 : The shared libraries required for MySQL clients
root-sql-mysql.i686 : MySQL client plugin for ROOT
mariadb-libs.i686 : The shared libraries required for MariaDB/MySQL clients
[root@localhost administrador]# yum install  -y community-mysql

Can enums be subclassed to add new elements?

Under the covers your ENUM is just a regular class generated by the compiler. That generated class extends java.lang.Enum. The technical reason you can't extend the generated class is that the generated class is final. The conceptual reasons for it being final are discussed in this topic. But I'll add the mechanics to the discussion.

Here is a test enum:

public enum TEST {  
    ONE, TWO, THREE;
}

The resulting code from javap:

public final class TEST extends java.lang.Enum<TEST> {
  public static final TEST ONE;
  public static final TEST TWO;
  public static final TEST THREE;
  static {};
  public static TEST[] values();
  public static TEST valueOf(java.lang.String);
}

Conceivably you could type this class on your own and drop the "final". But the compiler prevents you from extending "java.lang.Enum" directly. You could decide NOT to extend java.lang.Enum, but then your class and its derived classes would not be an instanceof java.lang.Enum ... which might not really matter to you any way!

When to favor ng-if vs. ng-show/ng-hide?

If you use ng-show or ng-hide the content (eg. thumbnails from server) will be loaded irrespective of the value of expression but will be displayed based on the value of the expression.

If you use ng-if the content will be loaded only if the expression of the ng-if evaluates to truthy.

Using ng-if is a good idea in a situation where you are going to load data or images from the server and show those only depending on users interaction. This way your page load will not be blocked by unnecessary nw intensive tasks.

Dynamically add item to jQuery Select2 control that uses AJAX

To get dynamic tagging to work with ajax, here's what I did.

Select2 version 3.5

This is easy in version 3.5 because it offers the createSearchChoice hook. It even works for multiple select, as long as multiple: true and tags: true are set.

HTML

<input type="hidden" name="locations" value="Whistler, BC" />

JS

$('input[name="locations"]').select2({
  tags: true,
  multiple: true,
  createSearchChoice: function(term, data) {
    if (!data.length)
      return { id: term, text: term };
    },
  ajax: {
    url: '/api/v1.1/locations',
    dataType: 'json'
  }
});

The idea here is to use select2's createSearchChoice hook which passes you both the term that the user entered and the ajax response (as data). If ajax returns an empty list, then tell select2 to offer the user-entered term as an option.

Demo: https://johnny.netlify.com/select2-examples/version3


Select2 version 4.X

Version 4.X doesn't have a createSearchChoice hook anymore, but here's how I did the same thing.

HTML

  <select name="locations" multiple>
    <option value="Whistler, BC" selected>Whistler, BC</option>
  </select>

JS

$('select[name="locations"]').select2({
  ajax: {
    url: '/api/v1.1/locations',
    dataType: 'json',
    data: function(params) {
      this.data('term', params.term);
      return params;
    },
    processResults: function(data) {
      if (data.length)
        return {
          results: data
        };
      else
        return {
          results: [{ id: this.$element.data('term'), text: this.$element.data('term') }]
        };
    }
  }
});

The ideas is to stash the term that the user typed into jQuery's data store inside select2's data hook. Then in select2's processResults hook, I check if the ajax response is empty. If it is, I grab the stashed term that the user typed and return it as an option to select2.

Demo: https://johnny.netlify.com/select2-examples/version4

Are there such things as variables within an Excel formula?

Not related to variables, your example will also be solved by MOD:

=Mod(VLOOKUP(A1, B:B, 1, 0);10)

Parser Error when deploy ASP.NET application

Looking at the error message, part of the code of your Default.aspx is :

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="AmeriaTestTask.Default" %>

but AmeriaTestTask.Default does not exists, so you have to change it, most probably to the class defined in Default.aspx.cs. For example for web api aplications, the class defined in Global.asax.cs is : public class WebApiApplication : System.Web.HttpApplication and in the asax page you have :

<%@ Application Codebehind="Global.asax.cs" Inherits="MyProject.WebApiApplication" Language="C#" %>

htaccess redirect to https://www

I used the below code from this website, it works great https://www.freecodecamp.org/news/how-to-redirect-http-to-https-using-htaccess/

_x000D_
_x000D_
RewriteEngine On_x000D_
RewriteCond %{SERVER_PORT} 80_x000D_
RewriteRule ^(.*)$ https://www.yourdomain.com/$1 [R,L]
_x000D_
_x000D_
_x000D_

Hope it helps

Cannot install packages using node package manager in Ubuntu

Simple solution from here

curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash --
sudo apt-get install nodejs

You can specify version by changing setup_x.x value, for example to setup_5.x

Getting Git to work with a proxy server - fails with "Request timed out"

I followed the most of the answers which was recommended here. First I got the following error:

fatal: unable to access 'https://github.com/folder/sample.git/': schannel: next InitializeSecurityContext failed: Unknown error (0x80092012) - The revocation function was unable to check revocation for the certificate.

Then I have tried the following command by @Salim Hamidi

git config --global http.proxy http://proxyuser:[email protected]:8080

But I got the following error:

fatal: unable to access 'https://github.com/folder/sample.git/': Received HTTP code 407 from proxy after CONNECT

This could happen if the proxy server can't verify the SSL certificate. So we want to make sure that the ssl verification is off (not recommended for non trusted sites), so I have done the following steps which was recommended by @Arpit but with slight changes:

1.First make sure to remove any previous proxy settings:

git config --global --unset http.proxy

2.Then list and get the gitconfig content

git config --list --show-origin

3.Last update the content of the gitconfig file as below:

[http]
sslCAInfo = C:/yourfolder/AppData/Local/Programs/Git/mingw64/ssl/certs/ca-bundle.crt
sslBackend = schannel
proxy = http://proxyuser:[email protected]:8080
sslverify = false
[https]
proxy = http://proxyuser:[email protected]:8080
sslverify = false

Customizing the template within a Directive

The above answers unfortunately don't quite work. In particular, the compile stage does not have access to scope, so you can't customize the field based on dynamic attributes. Using the linking stage seems to offer the most flexibility (in terms of asynchronously creating dom, etc.) The below approach addresses that:

<!-- Usage: -->
<form>
  <form-field ng-model="formModel[field.attr]" field="field" ng-repeat="field in fields">
</form>
// directive
angular.module('app')
.directive('formField', function($compile, $parse) {
  return { 
    restrict: 'E', 
    compile: function(element, attrs) {
      var fieldGetter = $parse(attrs.field);

      return function (scope, element, attrs) {
        var template, field, id;
        field = fieldGetter(scope);
        template = '..your dom structure here...'
        element.replaceWith($compile(template)(scope));
      }
    }
  }
})

I've created a gist with more complete code and a writeup of the approach.

Make a URL-encoded POST request using `http.NewRequest(...)`

URL-encoded payload must be provided on the body parameter of the http.NewRequest(method, urlStr string, body io.Reader) method, as a type that implements io.Reader interface.

Based on the sample code:

package main

import (
    "fmt"
    "net/http"
    "net/url"
    "strconv"
    "strings"
)

func main() {
    apiUrl := "https://api.com"
    resource := "/user/"
    data := url.Values{}
    data.Set("name", "foo")
    data.Set("surname", "bar")

    u, _ := url.ParseRequestURI(apiUrl)
    u.Path = resource
    urlStr := u.String() // "https://api.com/user/"

    client := &http.Client{}
    r, _ := http.NewRequest(http.MethodPost, urlStr, strings.NewReader(data.Encode())) // URL-encoded payload
    r.Header.Add("Authorization", "auth_token=\"XXXXXXX\"")
    r.Header.Add("Content-Type", "application/x-www-form-urlencoded")
    r.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))

    resp, _ := client.Do(r)
    fmt.Println(resp.Status)
}

resp.Status is 200 OK this way.

Git pull - Please move or remove them before you can merge

If you are getting error like

  • branch master -> FETCH_HEAD error: The following untracked working tree files would be overwritten by merge: src/dj/abc.html Please move or remove them before you merge. Aborting

Try removing the above file manually(Careful). Git will merge this file from master branch.

Declaring static constants in ES6 classes?

Here is one more way you can do

_x000D_
_x000D_
/*
one more way of declaring constants in a class,
Note - the constants have to be declared after the class is defined
*/
class Auto{
   //other methods
}
Auto.CONSTANT1 = "const1";
Auto.CONSTANT2 = "const2";

console.log(Auto.CONSTANT1)
console.log(Auto.CONSTANT2);
_x000D_
_x000D_
_x000D_

Note - the Order is important, you cannot have the constants above

Usage

console.log(Auto.CONSTANT1);

Script Tag - async & defer

HTML5: async, defer

In HTML5, you can tell browser when to run your JavaScript code. There are 3 possibilities:

<script       src="myscript.js"></script>

<script async src="myscript.js"></script>

<script defer src="myscript.js"></script>
  1. Without async or defer, browser will run your script immediately, before rendering the elements that's below your script tag.

  2. With async (asynchronous), browser will continue to load the HTML page and render it while the browser load and execute the script at the same time.

  3. With defer, browser will run your script when the page finished parsing. (not necessary finishing downloading all image files. This is good.)

Python Variable Declaration

There's no need to declare new variables in Python. If we're talking about variables in functions or modules, no declaration is needed. Just assign a value to a name where you need it: mymagic = "Magic". Variables in Python can hold values of any type, and you can't restrict that.

Your question specifically asks about classes, objects and instance variables though. The idiomatic way to create instance variables is in the __init__ method and nowhere else — while you could create new instance variables in other methods, or even in unrelated code, it's just a bad idea. It'll make your code hard to reason about or to maintain.

So for example:

class Thing(object):

    def __init__(self, magic):
        self.magic = magic

Easy. Now instances of this class have a magic attribute:

thingo = Thing("More magic")
# thingo.magic is now "More magic"

Creating variables in the namespace of the class itself leads to different behaviour altogether. It is functionally different, and you should only do it if you have a specific reason to. For example:

class Thing(object):

    magic = "Magic"

    def __init__(self):
        pass

Now try:

thingo = Thing()
Thing.magic = 1
# thingo.magic is now 1

Or:

class Thing(object):

    magic = ["More", "magic"]

    def __init__(self):
        pass

thing1 = Thing()
thing2 = Thing()
thing1.magic.append("here")
# thing1.magic AND thing2.magic is now ["More", "magic", "here"]

This is because the namespace of the class itself is different to the namespace of the objects created from it. I'll leave it to you to research that a bit more.

The take-home message is that idiomatic Python is to (a) initialise object attributes in your __init__ method, and (b) document the behaviour of your class as needed. You don't need to go to the trouble of full-blown Sphinx-level documentation for everything you ever write, but at least some comments about whatever details you or someone else might need to pick it up.

In Django, how do I check if a user is in a certain group?

I have done it the following way. Seems inefficient but I had no other way in my mind:

@login_required
def list_track(request):

usergroup = request.user.groups.values_list('name', flat=True).first()
if usergroup in 'appAdmin':
    tracks = QuestionTrack.objects.order_by('pk')
    return render(request, 'cmit/appadmin/list_track.html', {'tracks': tracks})

else:
    return HttpResponseRedirect('/cmit/loggedin')

Getting "project" nuget configuration is invalid error

NOTE: This is mentioned in the question but restarting Visual Studio fixes the issue in most cases.

Updating Visual Studio to 'Update 2' got it working again.

Tools -> Extensions and Updates ->Visual Studio Update 2

As mentioned in the question and the link i posted therein, I'd already updated NuGet Package Manager to 3.4.4 prior to this and restarted to no avail, so I don't know if the combination of both these actions worked.

plot a circle with pyplot

Similarly to scatter plot you can also use normal plot with circle line style. Using markersize parameter you can adjust radius of a circle:

import matplotlib.pyplot as plt

plt.plot(200, 2, 'o', markersize=7)

Installing packages in Sublime Text 2

The Installed Packages Directory You will find this directory in the data directory. It contains a copy of every sublime-package installed. Used to restore Packages

So, you shouldn't put any plugin to this folder. For getting works of SidebarEnhancements plugin try to disable and reenable this plugin with using Package Control. If it doesn't work then try to remove folder "SidebarEnhancements" from "Packages" folder and install it again via Package Control.

Best way to return a value from a python script

If you want your script to return values, just do return [1,2,3] from a function wrapping your code but then you'd have to import your script from another script to even have any use for that information:

Return values (from a wrapping-function)

(again, this would have to be run by a separate Python script and be imported in order to even do any good):

import ...
def main():
    # calculate stuff
    return [1,2,3]

Exit codes as indicators

(This is generally just good for when you want to indicate to a governor what went wrong or simply the number of bugs/rows counted or w/e. Normally 0 is a good exit and >=1 is a bad exit but you could inter-prate them in any way you want to get data out of it)

import sys
# calculate and stuff
sys.exit(100)

And exit with a specific exit code depending on what you want that to tell your governor. I used exit codes when running script by a scheduling and monitoring environment to indicate what has happened.

(os._exit(100) also works, and is a bit more forceful)

Stdout as your relay

If not you'd have to use stdout to communicate with the outside world (like you've described). But that's generally a bad idea unless it's a parser executing your script and can catch whatever it is you're reporting to.

import sys
# calculate stuff
sys.stdout.write('Bugs: 5|Other: 10\n')
sys.stdout.flush()
sys.exit(0)

Are you running your script in a controlled scheduling environment then exit codes are the best way to go.

Files as conveyors

There's also the option to simply write information to a file, and store the result there.

# calculate
with open('finish.txt', 'wb') as fh:
    fh.write(str(5)+'\n')

And pick up the value/result from there. You could even do it in a CSV format for others to read simplistically.

Sockets as conveyors

If none of the above work, you can also use network sockets locally *(unix sockets is a great way on nix systems). These are a bit more intricate and deserve their own post/answer. But editing to add it here as it's a good option to communicate between processes. Especially if they should run multiple tasks and return values.

Remove Item in Dictionary based on Value

Are you trying to remove a single value or all matching values?

If you are trying to remove a single value, how do you define the value you wish to remove?

The reason you don't get a key back when querying on values is because the dictionary could contain multiple keys paired with the specified value.

If you wish to remove all matching instances of the same value, you can do this:

foreach(var item in dic.Where(kvp => kvp.Value == value).ToList())
{
    dic.Remove(item.Key);
}

And if you wish to remove the first matching instance, you can query to find the first item and just remove that:

var item = dic.First(kvp => kvp.Value == value);

dic.Remove(item.Key);

Note: The ToList() call is necessary to copy the values to a new collection. If the call is not made, the loop will be modifying the collection it is iterating over, causing an exception to be thrown on the next attempt to iterate after the first value is removed.

How can I see function arguments in IPython Notebook Server 3?

Try Shift-Tab-Tab a bigger documentation appears, than with Shift-Tab. It's the same but you can scroll down.

Shift-Tab-Tab-Tab and the tooltip will linger for 10 seconds while you type.

Shift-Tab-Tab-Tab-Tab and the docstring appears in the pager (small part at the bottom of the window) and stays there.

Can I target all <H> tags with a single selector?

To tackle this with vanilla CSS look for patterns in the ancestors of the h1..h6 elements:

<section class="row">
  <header>
    <h1>AMD RX Series</h1>
    <small>These come in different brands and types</small>
  </header>
</header>

<div class="row">
  <h3>Sapphire RX460 OC 2/4GB</h3>
  <small>Available in 2GB and 4GB models</small>
</div>

If you can spot patterns you may be able to write a selector which targets what you want. Given the above example all h1..h6 elements may be targeted by combining the :first-child and :not pseudo-classes from CSS3, available in all modern browsers, like so:

.row :first-child:not(header) { /* ... */ }

In the future advanced pseudo-class selectors like :has(), and subsequent-sibling combinators (~), will provide even more control as Web standards continue to evolve over time.

Using Intent in an Android application to show another activity

When you create any activity in android file you have to specify it in AndroidManifest.xml like

<uses-sdk android:minSdkVersion="8" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
        android:name=".MyCreativityActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>


     <activity android:name=".OrderScreen"></activity>


</application>

Unsupported Media Type in postman

You need to set the content-type in postman as JSON (application/json).

Go to the body inside your POST request, there you will find the raw option.

Right next to it, there will be a drop down, select JSON (application.json).

Detecting an undefined object property

I'm surprised I haven't seen this suggestion yet, but it gets even more specificity than testing with typeof. Use Object.getOwnPropertyDescriptor() if you need to know whether an object property was initialized with undefined or if it was never initialized:

// to test someObject.someProperty
var descriptor = Object.getOwnPropertyDescriptor(someObject, 'someProperty');

if (typeof descriptor === 'undefined') {
  // was never initialized
} else if (typeof descriptor.value === 'undefined') {
  if (descriptor.get || descriptor.set) {
    // is an accessor property, defined via getter and setter
  } else {
    // is initialized with `undefined`
  }
} else {
  // is initialized with some other value
}

What's the best way of scraping data from a website?

You will definitely want to start with a good web scraping framework. Later on you may decide that they are too limiting and you can put together your own stack of libraries but without a lot of scraping experience your design will be much worse than pjscrape or scrapy.

Note: I use the terms crawling and scraping basically interchangeable here. This is a copy of my answer to your Quora question, it's pretty long.

Tools

Get very familiar with either Firebug or Chrome dev tools depending on your preferred browser. This will be absolutely necessary as you browse the site you are pulling data from and map out which urls contain the data you are looking for and what data formats make up the responses.

You will need a good working knowledge of HTTP as well as HTML and will probably want to find a decent piece of man in the middle proxy software. You will need to be able to inspect HTTP requests and responses and understand how the cookies and session information and query parameters are being passed around. Fiddler (http://www.telerik.com/fiddler) and Charles Proxy (http://www.charlesproxy.com/) are popular tools. I use mitmproxy (http://mitmproxy.org/) a lot as I'm more of a keyboard guy than a mouse guy.

Some kind of console/shell/REPL type environment where you can try out various pieces of code with instant feedback will be invaluable. Reverse engineering tasks like this are a lot of trial and error so you will want a workflow that makes this easy.

Language

PHP is basically out, it's not well suited for this task and the library/framework support is poor in this area. Python (Scrapy is a great starting point) and Clojure/Clojurescript (incredibly powerful and productive but a big learning curve) are great languages for this problem. Since you would rather not learn a new language and you already know Javascript I would definitely suggest sticking with JS. I have not used pjscrape but it looks quite good from a quick read of their docs. It's well suited and implements an excellent solution to the problem I describe below.

A note on Regular expressions: DO NOT USE REGULAR EXPRESSIONS TO PARSE HTML. A lot of beginners do this because they are already familiar with regexes. It's a huge mistake, use xpath or css selectors to navigate html and only use regular expressions to extract data from actual text inside an html node. This might already be obvious to you, it becomes obvious quickly if you try it but a lot of people waste a lot of time going down this road for some reason. Don't be scared of xpath or css selectors, they are WAY easier to learn than regexes and they were designed to solve this exact problem.

Javascript-heavy sites

In the old days you just had to make an http request and parse the HTML reponse. Now you will almost certainly have to deal with sites that are a mix of standard HTML HTTP request/responses and asynchronous HTTP calls made by the javascript portion of the target site. This is where your proxy software and the network tab of firebug/devtools comes in very handy. The responses to these might be html or they might be json, in rare cases they will be xml or something else.

There are two approaches to this problem:

The low level approach:

You can figure out what ajax urls the site javascript is calling and what those responses look like and make those same requests yourself. So you might pull the html from http://example.com/foobar and extract one piece of data and then have to pull the json response from http://example.com/api/baz?foo=b... to get the other piece of data. You'll need to be aware of passing the correct cookies or session parameters. It's very rare, but occasionally some required parameters for an ajax call will be the result of some crazy calculation done in the site's javascript, reverse engineering this can be annoying.

The embedded browser approach:

Why do you need to work out what data is in html and what data comes in from an ajax call? Managing all that session and cookie data? You don't have to when you browse a site, the browser and the site javascript do that. That's the whole point.

If you just load the page into a headless browser engine like phantomjs it will load the page, run the javascript and tell you when all the ajax calls have completed. You can inject your own javascript if necessary to trigger the appropriate clicks or whatever is necessary to trigger the site javascript to load the appropriate data.

You now have two options, get it to spit out the finished html and parse it or inject some javascript into the page that does your parsing and data formatting and spits the data out (probably in json format). You can freely mix these two options as well.

Which approach is best?

That depends, you will need to be familiar and comfortable with the low level approach for sure. The embedded browser approach works for anything, it will be much easier to implement and will make some of the trickiest problems in scraping disappear. It's also quite a complex piece of machinery that you will need to understand. It's not just HTTP requests and responses, it's requests, embedded browser rendering, site javascript, injected javascript, your own code and 2-way interaction with the embedded browser process.

The embedded browser is also much slower at scale because of the rendering overhead but that will almost certainly not matter unless you are scraping a lot of different domains. Your need to rate limit your requests will make the rendering time completely negligible in the case of a single domain.

Rate Limiting/Bot behaviour

You need to be very aware of this. You need to make requests to your target domains at a reasonable rate. You need to write a well behaved bot when crawling websites, and that means respecting robots.txt and not hammering the server with requests. Mistakes or negligence here is very unethical since this can be considered a denial of service attack. The acceptable rate varies depending on who you ask, 1req/s is the max that the Google crawler runs at but you are not Google and you probably aren't as welcome as Google. Keep it as slow as reasonable. I would suggest 2-5 seconds between each page request.

Identify your requests with a user agent string that identifies your bot and have a webpage for your bot explaining it's purpose. This url goes in the agent string.

You will be easy to block if the site wants to block you. A smart engineer on their end can easily identify bots and a few minutes of work on their end can cause weeks of work changing your scraping code on your end or just make it impossible. If the relationship is antagonistic then a smart engineer at the target site can completely stymie a genius engineer writing a crawler. Scraping code is inherently fragile and this is easily exploited. Something that would provoke this response is almost certainly unethical anyway, so write a well behaved bot and don't worry about this.

Testing

Not a unit/integration test person? Too bad. You will now have to become one. Sites change frequently and you will be changing your code frequently. This is a large part of the challenge.

There are a lot of moving parts involved in scraping a modern website, good test practices will help a lot. Many of the bugs you will encounter while writing this type of code will be the type that just return corrupted data silently. Without good tests to check for regressions you will find out that you've been saving useless corrupted data to your database for a while without noticing. This project will make you very familiar with data validation (find some good libraries to use) and testing. There are not many other problems that combine requiring comprehensive tests and being very difficult to test.

The second part of your tests involve caching and change detection. While writing your code you don't want to be hammering the server for the same page over and over again for no reason. While running your unit tests you want to know if your tests are failing because you broke your code or because the website has been redesigned. Run your unit tests against a cached copy of the urls involved. A caching proxy is very useful here but tricky to configure and use properly.

You also do want to know if the site has changed. If they redesigned the site and your crawler is broken your unit tests will still pass because they are running against a cached copy! You will need either another, smaller set of integration tests that are run infrequently against the live site or good logging and error detection in your crawling code that logs the exact issues, alerts you to the problem and stops crawling. Now you can update your cache, run your unit tests and see what you need to change.

Legal Issues

The law here can be slightly dangerous if you do stupid things. If the law gets involved you are dealing with people who regularly refer to wget and curl as "hacking tools". You don't want this.

The ethical reality of the situation is that there is no difference between using browser software to request a url and look at some data and using your own software to request a url and look at some data. Google is the largest scraping company in the world and they are loved for it. Identifying your bots name in the user agent and being open about the goals and intentions of your web crawler will help here as the law understands what Google is. If you are doing anything shady, like creating fake user accounts or accessing areas of the site that you shouldn't (either "blocked" by robots.txt or because of some kind of authorization exploit) then be aware that you are doing something unethical and the law's ignorance of technology will be extraordinarily dangerous here. It's a ridiculous situation but it's a real one.

It's literally possible to try and build a new search engine on the up and up as an upstanding citizen, make a mistake or have a bug in your software and be seen as a hacker. Not something you want considering the current political reality.

Who am I to write this giant wall of text anyway?

I've written a lot of web crawling related code in my life. I've been doing web related software development for more than a decade as a consultant, employee and startup founder. The early days were writing perl crawlers/scrapers and php websites. When we were embedding hidden iframes loading csv data into webpages to do ajax before Jesse James Garrett named it ajax, before XMLHTTPRequest was an idea. Before jQuery, before json. I'm in my mid-30's, that's apparently considered ancient for this business.

I've written large scale crawling/scraping systems twice, once for a large team at a media company (in Perl) and recently for a small team as the CTO of a search engine startup (in Python/Javascript). I currently work as a consultant, mostly coding in Clojure/Clojurescript (a wonderful expert language in general and has libraries that make crawler/scraper problems a delight)

I've written successful anti-crawling software systems as well. It's remarkably easy to write nigh-unscrapable sites if you want to or to identify and sabotage bots you don't like.

I like writing crawlers, scrapers and parsers more than any other type of software. It's challenging, fun and can be used to create amazing things.

How to efficiently concatenate strings in go

If you know the total length of the string that you're going to preallocate then the most efficient way to concatenate strings may be using the builtin function copy. If you don't know the total length before hand, do not use copy, and read the other answers instead.

In my tests, that approach is ~3x faster than using bytes.Buffer and much much faster (~12,000x) than using the operator +. Also, it uses less memory.

I've created a test case to prove this and here are the results:

BenchmarkConcat  1000000    64497 ns/op   502018 B/op   0 allocs/op
BenchmarkBuffer  100000000  15.5  ns/op   2 B/op        0 allocs/op
BenchmarkCopy    500000000  5.39  ns/op   0 B/op        0 allocs/op

Below is code for testing:

package main

import (
    "bytes"
    "strings"
    "testing"
)

func BenchmarkConcat(b *testing.B) {
    var str string
    for n := 0; n < b.N; n++ {
        str += "x"
    }
    b.StopTimer()

    if s := strings.Repeat("x", b.N); str != s {
        b.Errorf("unexpected result; got=%s, want=%s", str, s)
    }
}

func BenchmarkBuffer(b *testing.B) {
    var buffer bytes.Buffer
    for n := 0; n < b.N; n++ {
        buffer.WriteString("x")
    }
    b.StopTimer()

    if s := strings.Repeat("x", b.N); buffer.String() != s {
        b.Errorf("unexpected result; got=%s, want=%s", buffer.String(), s)
    }
}

func BenchmarkCopy(b *testing.B) {
    bs := make([]byte, b.N)
    bl := 0

    b.ResetTimer()
    for n := 0; n < b.N; n++ {
        bl += copy(bs[bl:], "x")
    }
    b.StopTimer()

    if s := strings.Repeat("x", b.N); string(bs) != s {
        b.Errorf("unexpected result; got=%s, want=%s", string(bs), s)
    }
}

// Go 1.10
func BenchmarkStringBuilder(b *testing.B) {
    var strBuilder strings.Builder

    b.ResetTimer()
    for n := 0; n < b.N; n++ {
        strBuilder.WriteString("x")
    }
    b.StopTimer()

    if s := strings.Repeat("x", b.N); strBuilder.String() != s {
        b.Errorf("unexpected result; got=%s, want=%s", strBuilder.String(), s)
    }
}

How to Calculate Jump Target Address and Branch Target Address?

For small functions like this you could just count by hand how many hops it is to the target, from the instruction under the branch instruction. If it branches backwards make that hop number negative. if that number doesn't require all 16 bits, then for every number to the left of the most significant of your hop number, make them 1's, if the hop number is positive make them all 0's Since most branches are close to they're targets, this saves you a lot of extra arithmetic for most cases.

  • chris

How do I print the content of a .txt file in Python?

to input a file:

fin = open(filename) #filename should be a string type: e.g filename = 'file.txt'

to output this file you can do:

for element in fin:
    print element 

if the elements are a string you'd better add this before print:

element = element.strip()

strip() remove notations like this: /n

Git - What is the difference between push.default "matching" and "simple"

From GIT documentation: Git Docs

Below gives the full information. In short, simple will only push the current working branch and even then only if it also has the same name on the remote. This is a very good setting for beginners and will become the default in GIT 2.0

Whereas matching will push all branches locally that have the same name on the remote. (Without regard to your current working branch ). This means potentially many different branches will be pushed, including those that you might not even want to share.

In my personal usage, I generally use a different option: current which pushes the current working branch, (because I always branch for any changes). But for a beginner I'd suggest simple

push.default
Defines the action git push should take if no refspec is explicitly given. Different values are well-suited for specific workflows; for instance, in a purely central workflow (i.e. the fetch source is equal to the push destination), upstream is probably what you want. Possible values are:

nothing - do not push anything (error out) unless a refspec is explicitly given. This is primarily meant for people who want to avoid mistakes by always being explicit.

current - push the current branch to update a branch with the same name on the receiving end. Works in both central and non-central workflows.

upstream - push the current branch back to the branch whose changes are usually integrated into the current branch (which is called @{upstream}). This mode only makes sense if you are pushing to the same repository you would normally pull from (i.e. central workflow).

simple - in centralized workflow, work like upstream with an added safety to refuse to push if the upstream branch's name is different from the local one.

When pushing to a remote that is different from the remote you normally pull from, work as current. This is the safest option and is suited for beginners.

This mode will become the default in Git 2.0.

matching - push all branches having the same name on both ends. This makes the repository you are pushing to remember the set of branches that will be pushed out (e.g. if you always push maint and master there and no other branches, the repository you push to will have these two branches, and your local maint and master will be pushed there).

To use this mode effectively, you have to make sure all the branches you would push out are ready to be pushed out before running git push, as the whole point of this mode is to allow you to push all of the branches in one go. If you usually finish work on only one branch and push out the result, while other branches are unfinished, this mode is not for you. Also this mode is not suitable for pushing into a shared central repository, as other people may add new branches there, or update the tip of existing branches outside your control.

This is currently the default, but Git 2.0 will change the default to simple.

"No rule to make target 'install'"... But Makefile exists

I was receiving the same error message, and my issue was that I was not in the correct directory when running the command make install. When I changed to the directory that had my makefile it worked.

So possibly you aren't in the right directory.

Adding a view controller as a subview in another view controller

Thanks to Rob, Updated Swift 4.2 syntax

let controller:WalletView = self.storyboard!.instantiateViewController(withIdentifier: "MyView") as! WalletView
controller.view.frame = self.view.bounds
self.view.addSubview(controller.view)
self.addChild(controller)
controller.didMove(toParent: self)

Pattern matching using a wildcard

You're on the right track - the keyword you should be googling is Regular Expressions. R does support them in a more direct way than this using grep() and a few other alternatives.

Here's a detailed discussion: http://www.regular-expressions.info/rlanguage.html

How to extract img src, title and alt from html using php?

I have read the many comments on this page that complain that using a dom parser is unnecessary overhead. Well, it may be more expensive than a mere regex call, but the OP has stated that there is no control over the order of the attributes in the img tags. This fact leads to unnecessary regex pattern convolution. Beyond that, using a dom parser provides the additional benefits of readability, maintainability, and dom-awareness (regex is not dom-aware).

I love regex and I answer lots of regex questions, but when dealing with valid HTML there is seldom a good reason to regex over a parser.

In the demonstration below, see how easy and clean DOMDocument handles img tag attributes in any order with a mixture of quoting (and no quoting at all). Also notice that tags without a targeted attribute are not disruptive at all -- an empty string is provided as a value.

Code: (Demo)

$test = <<<HTML
<img src="/image/fluffybunny.jpg" title="Harvey the bunny" alt="a cute little fluffy bunny" />
<img src='/image/pricklycactus.jpg' title='Roger the cactus' alt='a big green prickly cactus' />
<p>This is irrelevant text.</p>
<img alt="an annoying white cockatoo" title="Polly the cockatoo" src="/image/noisycockatoo.jpg">
<img title=something src=somethingelse>
HTML;

libxml_use_internal_errors(true);  // silences/forgives complaints from the parser (remove to see what is generated)
$dom = new DOMDocument();
$dom->loadHTML($test);
foreach ($dom->getElementsByTagName('img') as $i => $img) {
    echo "IMG#{$i}:\n";
    echo "\tsrc = " , $img->getAttribute('src') , "\n";
    echo "\ttitle = " , $img->getAttribute('title') , "\n";
    echo "\talt = " , $img->getAttribute('alt') , "\n";
    echo "---\n";
}

Output:

IMG#0:
    src = /image/fluffybunny.jpg
    title = Harvey the bunny
    alt = a cute little fluffy bunny
---
IMG#1:
    src = /image/pricklycactus.jpg
    title = Roger the cactus
    alt = a big green prickly cactus
---
IMG#2:
    src = /image/noisycockatoo.jpg
    title = Polly the cockatoo
    alt = an annoying white cockatoo
---
IMG#3:
    src = somethingelse
    title = something
    alt = 
---

Using this technique in professional code will leave you with a clean script, fewer hiccups to contend with, and fewer colleagues that wish you worked somewhere else.

Groovy method with optional parameters

Can't be done as it stands... The code

def myMethod(pParm1='1', pParm2='2'){
    println "${pParm1}${pParm2}"
}

Basically makes groovy create the following methods:

Object myMethod( pParm1, pParm2 ) {
    println "$pParm1$pParm2"
}

Object myMethod( pParm1 ) {
    this.myMethod( pParm1, '2' )
}

Object myMethod() {
    this.myMethod( '1', '2' )
}

One alternative would be to have an optional Map as the first param:

def myMethod( Map map = [:], String mandatory1, String mandatory2 ){
    println "${mandatory1} ${mandatory2} ${map.parm1 ?: '1'} ${map.parm2 ?: '2'}"
}

myMethod( 'a', 'b' )                // prints 'a b 1 2'
myMethod( 'a', 'b', parm1:'value' ) // prints 'a b value 2'
myMethod( 'a', 'b', parm2:'2nd')    // prints 'a b 1 2nd'

Obviously, documenting this so other people know what goes in the magical map and what the defaults are is left to the reader ;-)

"Uncaught TypeError: a.indexOf is not a function" error when opening new foundation project

This error is often caused by incompatible jQuery versions. I encountered the same error with a foundation 6 repository. My repository was using jQuery 3, but foundation requires an earlier version. I then changed it and it worked.

If you look at the version of jQuery required by the foundation 5 dependencies it states "jquery": "~2.1.0".

Can you confirm that you are loading the correct version of jQuery?

I hope this helps.

Check if argparse optional argument is set or not

If your argument is positional (ie it doesn't have a "-" or a "--" prefix, just the argument, typically a file name) then you can use the nargs parameter to do this:

parser = argparse.ArgumentParser(description='Foo is a program that does things')
parser.add_argument('filename', nargs='?')
args = parser.parse_args()

if args.filename is not None:
    print('The file name is {}'.format(args.filename))
else:
    print('Oh well ; No args, no problems')

Difference between using Throwable and Exception in a try catch

I have seen people use Throwable to catch some errors that might happen due to infra failure/ non availability.

Difference between logical addresses, and physical addresses?

A logical address is a reference to memory location independent of the current assignment of data to memory. A physical address or absolute address is an actual location in main memory.

It is in chapter 7.2 of Stallings.

Android: Scale a Drawable or background image?

The Below code make the bitmap perfectly with same size of the imageview. Get the bitmap image height and width and then calculate the new height and width with the help of imageview's parameters. That give you required image with best aspect ratio.

int bwidth=bitMap1.getWidth();
int bheight=bitMap1.getHeight();
int swidth=imageView_location.getWidth();
int sheight=imageView_location.getHeight();
new_width=swidth;
new_height = (int) Math.floor((double) bheight *( (double) new_width / (double) bwidth));
Bitmap newbitMap = Bitmap.createScaledBitmap(bitMap1,new_width,new_height, true);
imageView_location.setImageBitmap(newbitMap)

How to insert a file in MySQL database?

File size by MySQL type:

  • TINYBLOB 255 bytes = 0.000255 Mb
  • BLOB 65535 bytes = 0.0655 Mb
  • MEDIUMBLOB 16777215 bytes = 16.78 Mb
  • LONGBLOB 4294967295 bytes = 4294.97 Mb = 4.295 Gb

How to install an apk on the emulator in Android Studio?

1.Install Android studio. 2.Launch AVD Manager 3.Verify environment variable in set properly based on OS(.bash_profile in mac and environment Variable in windows) 4. launch emulator 5. verify via adb devices command. 6.use adb install apkFileName.apk

How do I tell if .NET 3.5 SP1 is installed?

Take a look at this article which shows the registry keys you need to look for and provides a .NET library that will do this for you.

First, you should to determine if .NET 3.5 is installed by looking at HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5\Install, which is a DWORD value. If that value is present and set to 1, then that version of the Framework is installed.

Look at HKLM\Software\Microsoft\NET Framework Setup\NDP\v3.5\SP, which is a DWORD value which indicates the Service Pack level (where 0 is no service pack).

To be correct about things, you really need to ensure that .NET Fx 2.0 and .NET Fx 3.0 are installed first and then check to see if .NET 3.5 is installed. If all three are true, then you can check for the service pack level.

Regex match one of two words

This will do:

/^(apple|banana)$/

to exclude from captured strings (e.g. $1,$2):

(?:apple|banana)

How to Make A Chevron Arrow Using CSS?

This can be solved much easier than the other suggestions.

Simply draw a square and apply a border property to just 2 joining sides.

Then rotate the square according to the direction you want the arrow to point, for exaple: transform: rotate(<your degree here>)

_x000D_
_x000D_
.triangle {_x000D_
    border-right: 10px solid; _x000D_
    border-bottom: 10px solid;_x000D_
    height: 30px;_x000D_
    width: 30px;_x000D_
    transform: rotate(-45deg);_x000D_
}
_x000D_
<div class="triangle"></div>
_x000D_
_x000D_
_x000D_

Express.js: how to get remote client address

In my case, similar to this solution, I ended up using the following x-forwarded-for approach:

let ip = (req.headers['x-forwarded-for'] || '').split(',')[0];

x-forwarded-for header will keep on adding the route of the IP from the origin all the way to the final destination server, thus if you need to retrieve the origin client's IP, this would be the first item of the array.

incompatible character encodings: ASCII-8BIT and UTF-8

I encountered the error while migrating an app from Ruby 1.8.7 to 1.9.3 and it only occured in production. It turned out that I had some leftovers in my Memcache store. The now encoding sensitive Ruby 1.9.3 version of my app tried to mix old ASCII-8BIT values with new UTF-8.

It was as simple as flushing the cache to fix it for me.

VBA array sort function?

Take a look here:
Edit: The referenced source (allexperts.com) has since closed, but here are the relevant author comments:

There are many algorithms available on the web for sorting. The most versatile and usually the quickest is the Quicksort algorithm. Below is a function for it.

Call it simply by passing an array of values (string or numeric; it doesn't matter) with the Lower Array Boundary (usually 0) and the Upper Array Boundary (i.e. UBound(myArray).)

Example: Call QuickSort(myArray, 0, UBound(myArray))

When it's done, myArray will be sorted and you can do what you want with it.
(Source: archive.org)

Public Sub QuickSort(vArray As Variant, inLow As Long, inHi As Long)
  Dim pivot   As Variant
  Dim tmpSwap As Variant
  Dim tmpLow  As Long
  Dim tmpHi   As Long

  tmpLow = inLow
  tmpHi = inHi

  pivot = vArray((inLow + inHi) \ 2)

  While (tmpLow <= tmpHi)
     While (vArray(tmpLow) < pivot And tmpLow < inHi)
        tmpLow = tmpLow + 1
     Wend

     While (pivot < vArray(tmpHi) And tmpHi > inLow)
        tmpHi = tmpHi - 1
     Wend

     If (tmpLow <= tmpHi) Then
        tmpSwap = vArray(tmpLow)
        vArray(tmpLow) = vArray(tmpHi)
        vArray(tmpHi) = tmpSwap
        tmpLow = tmpLow + 1
        tmpHi = tmpHi - 1
     End If
  Wend

  If (inLow < tmpHi) Then QuickSort vArray, inLow, tmpHi
  If (tmpLow < inHi) Then QuickSort vArray, tmpLow, inHi
End Sub

Note that this only works with single-dimensional (aka "normal"?) arrays. (There's a working multi-dimensional array QuickSort here.)

Checking character length in ruby

I think you could just use the String#length method...

http://ruby-doc.org/core-1.9.3/String.html#method-i-length

Example:

text = 'The quick brown fox jumps over the lazy dog.'
puts text.length > 25 ? 'Too many characters' : 'Accepted'

Can't compile C program on a Mac after upgrade to Mojave

The problem is that Xcode, especially Xcode 10.x, has not installed everything, so ensure the command line tools are installed, type this in a terminal shell:

xcode-select --install

also start Xcode and ensure all the required installation is installed ( you should get prompted if it is not.) and since Xcode 10 does not install the full Mac OS SDK, run the installer at

/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

as this package is not installed by Xcode 10.

Remove all occurrences of char from string

Use replaceAll instead of replace

str = str.replaceAll("X,"");

This should give you the desired answer.

Why are elementwise additions much faster in separate loops than in a combined loop?

OK, the right answer definitely has to do something with the CPU cache. But to use the cache argument can be quite difficult, especially without data.

There are many answers, that led to a lot of discussion, but let's face it: Cache issues can be very complex and are not one dimensional. They depend heavily on the size of the data, so my question was unfair: It turned out to be at a very interesting point in the cache graph.

@Mysticial's answer convinced a lot of people (including me), probably because it was the only one that seemed to rely on facts, but it was only one "data point" of the truth.

That's why I combined his test (using a continuous vs. separate allocation) and @James' Answer's advice.

The graphs below shows, that most of the answers and especially the majority of comments to the question and answers can be considered completely wrong or true depending on the exact scenario and parameters used.

Note that my initial question was at n = 100.000. This point (by accident) exhibits special behavior:

  1. It possesses the greatest discrepancy between the one and two loop'ed version (almost a factor of three)

  2. It is the only point, where one-loop (namely with continuous allocation) beats the two-loop version. (This made Mysticial's answer possible, at all.)

The result using initialized data:

Enter image description here

The result using uninitialized data (this is what Mysticial tested):

Enter image description here

And this is a hard-to-explain one: Initialized data, that is allocated once and reused for every following test case of different vector size:

Enter image description here

Proposal

Every low-level performance related question on Stack Overflow should be required to provide MFLOPS information for the whole range of cache relevant data sizes! It's a waste of everybody's time to think of answers and especially discuss them with others without this information.

Can't open and lock privilege tables: Table 'mysql.user' doesn't exist

in laragon delete all internal data files from "C:\laragon\data\mysql" and restart it, that worked for me

How to rotate portrait/landscape Android emulator?

See the Android documentation on controlling the emulator; it's Ctrl + F11 / Ctrl + F12.

On ThinkPad running Ubuntu, you may try CTRL + Left Arrow Key or Right Arrow Key

How to check if a function exists on a SQL database

I've found you can use a very non verbose and straightforward approach to checking for the existence various SQL Server objects this way:

IF OBJECTPROPERTY (object_id('schemaname.scalarfuncname'), 'IsScalarFunction') = 1
IF OBJECTPROPERTY (object_id('schemaname.tablefuncname'), 'IsTableFunction') = 1
IF OBJECTPROPERTY (object_id('schemaname.procname'), 'IsProcedure') = 1

This is based on the OBJECTPROPERTY function which is available in SQL 2005+. The MSDN article can be found here.

The OBJECTPROPERTY function uses the following signature:

OBJECTPROPERTY ( id , property ) 

You pass a literal value into the property parameter, designating the type of object you are looking for. There's a massive list of values you can supply.

Convert a string representation of a hex dump to a byte array using Java?

The Hex class in commons-codec should do that for you.

http://commons.apache.org/codec/

import org.apache.commons.codec.binary.Hex;
...
byte[] decoded = Hex.decodeHex("00A0BF");
// 0x00 0xA0 0xBF

How do I set response headers in Flask?

This was how added my headers in my flask application and it worked perfectly

@app.after_request
def add_header(response):
    response.headers['X-Content-Type-Options'] = 'nosniff'
    return response

SmartGit Installation and Usage on Ubuntu

Now on the Smartgit webpage (I don't know since when) there is the possibility to download directly the .deb package. Once installed, it will upgrade automagically itself when a new version is released.

How do I install Python 3 on an AWS EC2 instance?

As @NickT said, there's no python3[4-6] in the default yum repos in Amazon Linux 2, as of today it uses 3.7 and looking at all answers here we can say it will be changed over time.

I was looking for python3.6 on Amazon Linux 2 but amazon-linux-extras shows a lot of options but no python at all. in fact, you can try to find the version you know in epel repo:

sudo amazon-linux-extras install epel

yum search python | grep "^python3..x8"

python34.x86_64 : Version 3 of the Python programming language aka Python 3000
python36.x86_64 : Interpreter of the Python programming language

Getting multiple keys of specified value of a generic Dictionary?

Then layman's solution

A function similar to the one below could be written to make such a dictionary:

    public Dictionary<TValue, TKey> Invert(Dictionary<TKey, TValue> dict) {
    Dictionary<TValue, TKey> ret = new Dictionary<TValue, TKey>();
    foreach (var kvp in dict) {ret[kvp.value] = kvp.key;} return ret; }

Git commit with no commit message

The commit message is a best practice that should be followed at all times. Unless you're the only developer and that isn't going to change any time soon.

git commit -a -m 'asdfasdfadsfsdf'

How to make input type= file Should accept only pdf and xls

You could do so by using the attribute accept and adding allowed mime-types to it. But not all browsers do respect that attribute and it could easily be removed via some code inspector. So in either case you need to check the file type on the server side (your second question).

Example:

<input type="file" name="upload" accept="application/pdf,application/vnd.ms-excel" />

To your third question "And when I click the files (PDF/XLS) on webpage it automatically should open.":

You can't achieve that. How a PDF or XLS is opened on the client machine is set by the user.

sudo echo "something" >> /etc/privilegedFile doesn't work

The issue is that it's your shell that handles redirection; it's trying to open the file with your permissions not those of the process you're running under sudo.

Use something like this, perhaps:

sudo sh -c "echo 'something' >> /etc/privilegedFile"

'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.

Eclipse: Error ".. overlaps the location of another project.." when trying to create new project

In my case checking the check-box

"Copy project into workspace"

did the trick.

"Permission Denied" trying to run Python on Windows 10

This appears to be a limitation in git-bash. The recommendation to use winpty python.exe worked for me. See Python not working in the command line of git bash for additional information.

call javascript function onchange event of dropdown list

Your code is working just fine, you have to declare javscript method before DOM ready.

your working example

Django database query: How to get object by id?

I got here for the same problem, but for a different reason:

Class.objects.get(id=1)

This code was raising an ImportError exception. What was confusing me was that the code below executed fine and returned a result set as expected:

Class.objects.all()

Tail of the traceback for the get() method:

File "django/db/models/loading.py", line 197, in get_models
    self._populate()
File "django/db/models/loading.py", line 72, in _populate
    self.load_app(app_name, True)
File "django/db/models/loading.py", line 94, in load_app
    app_module = import_module(app_name)
File "django/utils/importlib.py", line 35, in import_module
    __import__(name)
ImportError: No module named myapp

Reading the code inside Django's loading.py, I came to the conclusion that my settings.py had a bad path to my app which contains my Class model definition. All I had to do was correct the path to the app and the get() method executed fine.

Here is my settings.py with the corrected path:

INSTALLED_APPS = (
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    # ...
    'mywebproject.myapp',

)

All the confusion was caused because I am using Django's ORM as a standalone, so the namespace had to reflect that.

Apache error: _default_ virtualhost overlap on port 443

On a vanilla Apache2 install in CentOS, when you install mod_ssl it will automatically add a configuration file in:

{apache_dir}/conf.d/ssl.conf

This configuration file contains a default virtual host definition for port 443, named default:443. If you also have your own virtual host definition for 443 (i.e. in httpd.conf) then you will have a confict. Since the conf.d files are included first, they will win over yours.

To solve the conflict you can either remove the virtual host definition from conf.d/ssl.conf or update it to your own settings.

How to ISO 8601 format a Date with Timezone Offset in JavaScript?

function setDate(){
    var now = new Date();
    now.setMinutes(now.getMinutes() - now.getTimezoneOffset());
    var timeToSet = now.toISOString().slice(0,16);

    /*
        If you have an element called "eventDate" like the following:

        <input type="datetime-local" name="eventdate" id="eventdate" />

        and you would like to  set the current and minimum time then use the following:
    */

    var elem = document.getElementById("eventDate");
    elem.value = timeToSet;
    elem.min = timeToSet;
}

Getting the minimum of two values in SQL

Use a temp table to insert the range of values, then select the min/max of the temp table from within a stored procedure or UDF. This is a basic construct, so feel free to revise as needed.

For example:

CREATE PROCEDURE GetMinSpeed() AS
BEGIN

    CREATE TABLE #speed (Driver NVARCHAR(10), SPEED INT);
    '
    ' Insert any number of data you need to sort and pull from
    '
    INSERT INTO #speed (N'Petty', 165)
    INSERT INTO #speed (N'Earnhardt', 172)
    INSERT INTO #speed (N'Patrick', 174)

    SELECT MIN(SPEED) FROM #speed

    DROP TABLE #speed

END

Error: "setFile(null,false) call failed" when using log4j

i just add write permission to "logs" folder and it works for me

add write permission