Programs & Examples On #Hex

Hexadecimal (also base 16, or hex) is the base-16 positional numeral system, using the 16 symbols 0–9 and A‒F.

Python Hexadecimal

Another solution is:

>>> "".join(list(hex(255))[2:])
'ff'

Probably an archaic answer, but functional.

Javascript: Unicode string to hex

Here you go. :D

"??".split("").reduce((hex,c)=>hex+=c.charCodeAt(0).toString(16).padStart(4,"0"),"")
"6f225b57"

for non unicode

"hi".split("").reduce((hex,c)=>hex+=c.charCodeAt(0).toString(16).padStart(2,"0"),"")
"6869"

ASCII (utf-8) binary HEX string to string

"68656c6c6f20776f726c6421".match(/.{1,2}/g).reduce((acc,char)=>acc+String.fromCharCode(parseInt(char, 16)),"")

String to ASCII (utf-8) binary HEX string

"hello world!".split("").reduce((hex,c)=>hex+=c.charCodeAt(0).toString(16).padStart(2,"0"),"")

--- unicode ---

String to UNICODE (utf-16) binary HEX string

"hello world!".split("").reduce((hex,c)=>hex+=c.charCodeAt(0).toString(16).padStart(4,"0"),"")

UNICODE (utf-16) binary HEX string to string

"00680065006c006c006f00200077006f0072006c00640021".match(/.{1,4}/g).reduce((acc,char)=>acc+String.fromCharCode(parseInt(char, 16)),"")

How to convert numbers between hexadecimal and decimal

It looks like you can say

Convert.ToInt64(value, 16)

to get the decimal from hexdecimal.

The other way around is:

otherVar.ToString("X");

byte[] to hex string

You have to know the encoding of the string represented in bytes, but you can say System.Text.UTF8Encoding.GetString(bytes) or System.Text.ASCIIEncoding.GetString(bytes). (I'm doing this from memory, so the API may not be exactly correct, but it's very close.)

For the answer to your second question, see this question.

Need a good hex editor for Linux

I am a VIMer. I can do some rare Hex edits with:

  • :%!xxd to switch into hex mode

  • :%!xxd -r to exit from hex mode

But I strongly recommend ht

apt-cache show ht

Package: ht
Version: 2.0.18-1
Installed-Size: 1780
Maintainer: Alexander Reichle-Schmehl <[email protected]>

Homepage: http://hte.sourceforge.net/

Note: The package is called ht, whereas the executable is named hte after the package was installed.

  1. Supported file formats
    • common object file format (COFF/XCOFF32)
    • executable and linkable format (ELF)
    • linear executables (LE)
    • standard DO$ executables (MZ)
    • new executables (NE)
    • portable executables (PE32/PE64)
    • java class files (CLASS)
    • Mach exe/link format (MachO)
    • X-Box executable (XBE)
    • Flat (FLT)
    • PowerPC executable format (PEF)
  2. Code & Data Analyser
    • finds branch sources and destinations recursively
    • finds procedure entries
    • creates labels based on this information
    • creates xref information
    • allows to interactively analyse unexplored code
    • allows to create/rename/delete labels
    • allows to create/edit comments
    • supports x86, ia64, alpha, ppc and java code
  3. Target systems
    • DJGPP
    • GNU/Linux
    • FreeBSD
    • OpenBSD
    • Win32

How to convert decimal to hexadecimal in JavaScript

Constrained/padded to a set number of characters:

function decimalToHex(decimal, chars) {
    return (decimal + Math.pow(16, chars)).toString(16).slice(-chars).toUpperCase();
}

How to display hexadecimal numbers in C?

You can use the following snippet code:

#include<stdio.h>
int main(int argc, char *argv[]){
    unsigned int i;
    printf("decimal  hexadecimal\n");
    for (i = 0; i <= 256; i+=16)
        printf("%04d     0x%04X\n", i, i);
    return 0;
}

It prints both decimal and hexadecimal numbers in 4 places with zero padding.

Print a variable in hexadecimal in Python

Convert the string to an integer base 16 then to hexadecimal.

print hex(int(string, base=16))

These are built-in functions.

http://docs.python.org/2/library/functions.html#int

Example

>>> string = 'AA'
>>> _int = int(string, base=16)
>>> _hex = hex(_int)
>>> print _int
170
>>> print _hex
0xaa
>>> 

How do you convert a byte array to a hexadecimal string, and vice versa?

Another way is by using stackalloc to reduce GC memory pressure:

static string ByteToHexBitFiddle(byte[] bytes)
{
        var c = stackalloc char[bytes.Length * 2 + 1];
        int b; 
        for (int i = 0; i < bytes.Length; ++i)
        {
            b = bytes[i] >> 4;
            c[i * 2] = (char)(55 + b + (((b - 10) >> 31) & -7));
            b = bytes[i] & 0xF;
            c[i * 2 + 1] = (char)(55 + b + (((b - 10) >> 31) & -7));
        }
        c[bytes.Length * 2 ] = '\0';
        return new string(c);
}

What is 0x10 in decimal?

The simple version is 0x is a prefix denoting a hexadecimal number, source.

So the value you're computing is after the prefix, in this case 10.

But that is not the number 10. The most significant bit 1 denotes the hex value while 0 denotes the units.

So the simple math you would do is

0x10

1 * 16 + 0 = 16

Note - you use 16 because hex is base 16.

Another example:

0xF7

15 * 16 + 7 = 247

You can get a list of values by searching for a hex table. For instance in this chart notice F corresponds with 15.

What's the correct way to convert bytes to a hex string in Python 3?

New in python 3.8, you can pass a delimiter argument to the hex function, as in this example

>>> value = b'\xf0\xf1\xf2'
>>> value.hex('-')
'f0-f1-f2'
>>> value.hex('_', 2)
'f0_f1f2'
>>> b'UUDDLRLRAB'.hex(' ', -4)
'55554444 4c524c52 4142'

https://docs.python.org/3/library/stdtypes.html#bytes.hex

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

EDIT: as pointed out by @mmyers, this method doesn't work on input that contains substrings corresponding to bytes with the high bit set ("80" - "FF"). The explanation is at Bug ID: 6259307 Byte.parseByte not working as advertised in the SDK Documentation.

public static final byte[] fromHexString(final String s) {
    byte[] arr = new byte[s.length()/2];
    for ( int start = 0; start < s.length(); start += 2 )
    {
        String thisByte = s.substring(start, start+2);
        arr[start/2] = Byte.parseByte(thisByte, 16);
    }
    return arr;
}

Python convert decimal to hex

def tohex(dec):
    x = (dec%16)
    igits = "0123456789ABCDEF"
    digits = list(igits)
    rest = int(dec/16)
    if (rest == 0):
        return digits[x]
    return tohex(rest) + digits[x]

numbers = [0,16,32,48,46,2,55,887]
hex_ = ["0x"+tohex(i) for i in numbers]
print(hex_)

Convert from ASCII string encoded in Hex to plain ASCII?

Here's my solution when working with hex integers and not hex strings:

def convert_hex_to_ascii(h):
    chars_in_reverse = []
    while h != 0x0:
        chars_in_reverse.append(chr(h & 0xFF))
        h = h >> 8

    chars_in_reverse.reverse()
    return ''.join(chars_in_reverse)

print convert_hex_to_ascii(0x7061756c)

Convert A String (like testing123) To Binary In Java

You can also do this with the ol' good method :

String inputLine = "test123";
String translatedString = null;
char[] stringArray = inputLine.toCharArray();
for(int i=0;i<stringArray.length;i++){
      translatedString += Integer.toBinaryString((int) stringArray[i]);
}

RGB to hex and hex to RGB

I found this and because I think it is pretty straight forward and has validation tests and supports alpha values (optional), this will fit the case.

Just comment out the regex line if you know what you're doing and it's a tiny bit faster.

function hexToRGBA(hex, alpha){
    hex = (""+hex).trim().replace(/#/g,""); //trim and remove any leading # if there (supports number values as well)
    if (!/^(?:[0-9a-fA-F]{3}){1,2}$/.test(hex)) throw ("not a valid hex string"); //Regex Validator
    if (hex.length==3){hex=hex[0]+hex[0]+hex[1]+hex[1]+hex[2]+hex[2]} //support short form
    var b_int = parseInt(hex, 16);
    return "rgba("+[
        (b_int >> 16) & 255, //R
        (b_int >> 8) & 255, //G
        b_int & 255, //B
        alpha || 1  //add alpha if is set
    ].join(",")+")";
}

How to convert hex string to Java string?

byte[] bytes = javax.xml.bind.DatatypeConverter.parseHexBinary(hexString);
String result= new String(bytes, encoding);

Convert a hexadecimal string to an integer efficiently in C?

For larger Hex strings like in the example I needed to use strtoul.

How to create a hex dump of file containing only the hex characters without spaces in bash?

It seems to depend on the details of the version of od. On OSX, use this:

od -t x1 -An file |tr -d '\n '

(That's print as type hex bytes, with no address. And whitespace deleted afterwards, of course.)

Converting Hexadecimal String to Decimal Integer

This is a little library that should help you with hexadecimals in Java: https://github.com/PatrykSitko/HEX4J

It can convert from and to hexadecimals. It supports:

  • byte
  • boolean
  • char
  • char[]
  • String
  • short
  • int
  • long
  • float
  • double (signed and unsigned)

With it, you can convert your String to hexadecimal and the hexadecimal to a float/double.

Example:

String hexValue = HEX4J.Hexadecimal.from.String("Hello World");
double doubleValue = HEX4J.Hexadecimal.to.Double(hexValue);

Convert decimal to hexadecimal in UNIX shell script

Tried printf(1)?

printf "%x\n" 34
22

There are probably ways of doing that with builtin functions in all shells but it would be less portable. I've not checked the POSIX sh specs to see whether it has such capabilities.

Printing hexadecimal characters in C

You are probably printing from a signed char array. Either print from an unsigned char array or mask the value with 0xff: e.g. ar[i] & 0xFF. The c0 values are being sign extended because the high (sign) bit is set.

How can I convert a hex string to a byte array?

I think this may work.

public static byte[] StrToByteArray(string str)
    {
        Dictionary<string, byte> hexindex = new Dictionary<string, byte>();
        for (int i = 0; i <= 255; i++)
            hexindex.Add(i.ToString("X2"), (byte)i);

        List<byte> hexres = new List<byte>();
        for (int i = 0; i < str.Length; i += 2)            
            hexres.Add(hexindex[str.Substring(i, 2)]);

        return hexres.ToArray();
    }

Why are hexadecimal numbers prefixed with 0x?

It's a prefix to indicate the number is in hexadecimal rather than in some other base. The C programming language uses it to tell compiler.

Example:

0x6400 translates to 6*16^3 + 4*16^2 + 0*16^1 +0*16^0 = 25600. When compiler reads 0x6400, It understands the number is hexadecimal with the help of 0x term. Usually we can understand by (6400)16 or (6400)8 or whatever ..

For binary it would be:

0b00000001

Hope I have helped in some way.

Good day!

How to convert an int to a hex string?

This worked best for me

"0x%02X" % 5  # => 0x05
"0x%02X" % 17 # => 0x11

Change the (2) if you want a number with a bigger width (2 is for 2 hex printned chars) so 3 will give you the following

"0x%03X" % 5  # => 0x005
"0x%03X" % 17 # => 0x011

Understanding colors on Android (six characters)

On Android, colors are can be specified as RGB or ARGB.

http://en.wikipedia.org/wiki/ARGB

In RGB you have two characters for every color (red, green, blue), and in ARGB you have two additional chars for the alpha channel.

So, if you have 8 characters, it's ARGB, with the first two characters specifying the alpha channel. If you remove the leading two characters it's only RGB (solid colors, no alpha/transparency). If you want to specify a color in your Java source code, you have to use:

int Color.argb (int alpha, int red, int green, int blue)

alpha  Alpha component [0..255] of the color
red    Red component [0..255] of the color
green  Green component [0..255] of the color
blue   Blue component [0..255] of the color

Reference: argb

Hexadecimal To Decimal in Shell Script

The error as reported appears when the variables are null (or empty):

$ unset var3 var4; var5=$(($var4-$var3))
bash: -: syntax error: operand expected (error token is "-")

That could happen because the value given to bc was incorrect. That might well be that bc needs UPPERcase values. It needs BFCA3000, not bfca3000. That is easily fixed in bash, just use the ^^ expansion:

var3=bfca3000; var3=`echo "ibase=16; ${var1^^}" | bc`

That will change the script to this:

#!/bin/bash

var1="bfca3000"
var2="efca3250"

var3="$(echo "ibase=16; ${var1^^}" | bc)"
var4="$(echo "ibase=16; ${var2^^}" | bc)"

var5="$(($var4-$var3))"

echo "Diference $var5"

But there is no need to use bc [1], as bash could perform the translation and substraction directly:

#!/bin/bash

var1="bfca3000"
var2="efca3250"

var5="$(( 16#$var2 - 16#$var1 ))"

echo "Diference $var5"

[1]Note: I am assuming the values could be represented in 64 bit math, as the difference was calculated in bash in your original script. Bash is limited to integers less than ((2**63)-1) if compiled in 64 bits. That will be the only difference with bc which does not have such limit.

String.Format for Hex

The number 0 in {0:X} refers to the position in the list or arguments. In this case 0 means use the first value, which is Blue. Use {1:X} for the second argument (Green), and so on.

colorstring = String.Format("#{0:X}{1:X}{2:X}{3:X}", Blue, Green, Red, Space);

The syntax for the format parameter is described in the documentation:

Format Item Syntax

Each format item takes the following form and consists of the following components:

{ index[,alignment][:formatString]}

The matching braces ("{" and "}") are required.

Index Component

The mandatory index component, also called a parameter specifier, is a number starting from 0 that identifies a corresponding item in the list of objects. That is, the format item whose parameter specifier is 0 formats the first object in the list, the format item whose parameter specifier is 1 formats the second object in the list, and so on.

Multiple format items can refer to the same element in the list of objects by specifying the same parameter specifier. For example, you can format the same numeric value in hexadecimal, scientific, and number format by specifying a composite format string like this: "{0:X} {0:E} {0:N}".

Each format item can refer to any object in the list. For example, if there are three objects, you can format the second, first, and third object by specifying a composite format string like this: "{1} {0} {2}". An object that is not referenced by a format item is ignored. A runtime exception results if a parameter specifier designates an item outside the bounds of the list of objects.

Alignment Component

The optional alignment component is a signed integer indicating the preferred formatted field width. If the value of alignment is less than the length of the formatted string, alignment is ignored and the length of the formatted string is used as the field width. The formatted data in the field is right-aligned if alignment is positive and left-aligned if alignment is negative. If padding is necessary, white space is used. The comma is required if alignment is specified.

Format String Component

The optional formatString component is a format string that is appropriate for the type of object being formatted. Specify a standard or custom numeric format string if the corresponding object is a numeric value, a standard or custom date and time format string if the corresponding object is a DateTime object, or an enumeration format string if the corresponding object is an enumeration value. If formatString is not specified, the general ("G") format specifier for a numeric, date and time, or enumeration type is used. The colon is required if formatString is specified.

Note that in your case you only have the index and the format string. You have not specified (and do not need) an alignment component.

Decimal to Hexadecimal Converter in Java

One possible solution:

import java.lang.StringBuilder;

class Test {
  private static final int sizeOfIntInHalfBytes = 8;
  private static final int numberOfBitsInAHalfByte = 4;
  private static final int halfByte = 0x0F;
  private static final char[] hexDigits = { 
    '0', '1', '2', '3', '4', '5', '6', '7', 
    '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
  };

  public static String decToHex(int dec) {
    StringBuilder hexBuilder = new StringBuilder(sizeOfIntInHalfBytes);
    hexBuilder.setLength(sizeOfIntInHalfBytes);
    for (int i = sizeOfIntInHalfBytes - 1; i >= 0; --i)
    {
      int j = dec & halfByte;
      hexBuilder.setCharAt(i, hexDigits[j]);
      dec >>= numberOfBitsInAHalfByte;
    }
    return hexBuilder.toString(); 
  }

  public static void main(String[] args) {
     int dec = 305445566;
     String hex = decToHex(dec);
     System.out.println(hex);       
  }
}

Output:

1234BABE

Anyway, there is a library method for this:

String hex = Integer.toHexString(dec);

How to convert hex strings to byte values in Java

Looking at the sample I guess you mean that a string array is actually an array of HEX representation of bytes, don't you?

If yes, then for each string item I would do the following:

  1. check that a string consists only of 2 characters
  2. these chars are in '0'..'9' or 'a'..'f' interval (take their case into account as well)
  3. convert each character to a corresponding number, subtracting code value of '0' or 'a'
  4. build a byte value, where first char is higher bits and second char is lower ones. E.g.

    int byteVal = (firstCharNumber << 4) | secondCharNumber;
    

Python 3.1.1 string to hex

You've already got some good answers, but I thought you might be interested in a bit of the background too.

Firstly you're missing the quotes. It should be:

"hello".encode("hex")

Secondly this codec hasn't been ported to Python 3.1. See here. It seems that they haven't yet decided whether or not these codecs should be included in Python 3 or implemented in a different way.

If you look at the diff file attached to that bug you can see the proposed method of implementing it:

import binascii
output = binascii.b2a_hex(input)

What's a good hex editor/viewer for the Mac?

On http://www.synalysis.net/ you can get the hex editor I'm developing for the Mac - Synalyze It!. It costs 7 € / 40 € (Pro version) and offers some extra features like histogram, incremental search, support of many text encodings and interactive definition of a "grammar" for your file format.

The grammar helps to interpret the files and colors the hex view for easier analysis.

Synalyze It!

C++ convert hex string to signed integer

use std::stringstream

unsigned int x;   
std::stringstream ss;
ss << std::hex << "fffefffe";
ss >> x;

the following example produces -65538 as its result:

#include <sstream>
#include <iostream>

int main() {
    unsigned int x;   
    std::stringstream ss;
    ss << std::hex << "fffefffe";
    ss >> x;
    // output it as a signed type
    std::cout << static_cast<int>(x) << std::endl;
}

In the new C++11 standard, there are a few new utility functions which you can make use of! specifically, there is a family of "string to number" functions (http://en.cppreference.com/w/cpp/string/basic_string/stol and http://en.cppreference.com/w/cpp/string/basic_string/stoul). These are essentially thin wrappers around C's string to number conversion functions, but know how to deal with a std::string

So, the simplest answer for newer code would probably look like this:

std::string s = "0xfffefffe";
unsigned int x = std::stoul(s, nullptr, 16);

NOTE: Below is my original answer, which as the edit says is not a complete answer. For a functional solution, stick the code above the line :-).

It appears that since lexical_cast<> is defined to have stream conversion semantics. Sadly, streams don't understand the "0x" notation. So both the boost::lexical_cast and my hand rolled one don't deal well with hex strings. The above solution which manually sets the input stream to hex will handle it just fine.

Boost has some stuff to do this as well, which has some nice error checking capabilities as well. You can use it like this:

try {
    unsigned int x = lexical_cast<int>("0x0badc0de");
} catch(bad_lexical_cast &) {
    // whatever you want to do...
}

If you don't feel like using boost, here's a light version of lexical cast which does no error checking:

template<typename T2, typename T1>
inline T2 lexical_cast(const T1 &in) {
    T2 out;
    std::stringstream ss;
    ss << in;
    ss >> out;
    return out;
}

which you can use like this:

// though this needs the 0x prefix so it knows it is hex
unsigned int x = lexical_cast<unsigned int>("0xdeadbeef"); 

Convert integer to hexadecimal and back again

NET FRAMEWORK

Very well explained and few programming lines GOOD JOB

// Store integer 182
int intValue = 182;
// Convert integer 182 as a hex in a string variable
string hexValue = intValue.ToString("X");
// Convert the hex string back to the number
int intAgain = int.Parse(hexValue, System.Globalization.NumberStyles.HexNumber);

PASCAL >> C#

http://files.hddguru.com/download/Software/Seagate/St_mem.pas

Something from the old school very old procedure of pascal converted to C #

    /// <summary>
    /// Conver number from Decadic to Hexadecimal
    /// </summary>
    /// <param name="w"></param>
    /// <returns></returns>
    public string MakeHex(int w)
    {
        try
        {
           char[] b =  {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
           char[] S = new char[7];

              S[0] = b[(w >> 24) & 15];
              S[1] = b[(w >> 20) & 15];
              S[2] = b[(w >> 16) & 15];
              S[3] = b[(w >> 12) & 15];
              S[4] = b[(w >> 8) & 15];
              S[5] = b[(w >> 4) & 15];
              S[6] = b[w & 15];

              string _MakeHex = new string(S, 0, S.Count());

              return _MakeHex;
        }
        catch (Exception ex)
        {

            throw;
        }
    }

Convert bytes to bits in python

To binary:

bin(byte)[2:].zfill(8)

bitwise XOR of hex numbers in python

If the two hex strings are the same length and you want a hex string output then you might try this.

def hexxor(a, b):    # xor two hex strings of the same length
    return "".join(["%x" % (int(x,16) ^ int(y,16)) for (x, y) in zip(a, b)])

How do I convert a single character into it's hex ascii value in python

To use the hex encoding in Python 3, use

>>> import codecs
>>> codecs.encode(b"c", "hex")
b'63'

In legacy Python, there are several other ways of doing this:

>>> hex(ord("c"))
'0x63'
>>> format(ord("c"), "x")
'63'
>>> "c".encode("hex")
'63'

Convert hex string to int

This is the right answer:

myPassedColor = "#ffff8c85" int colorInt = Color.parseColor(myPassedColor)

Transparent ARGB hex value

Just came across this and the short code for transparency is simply #00000000.

How to get the background color code of an element in hex?

You have the color you just need to convert it into the format you want.

Here's a script that should do the trick: http://www.phpied.com/rgb-color-parser-in-javascript/

How do I get the color from a hexadecimal color code using .NET?

There is also this neat little extension method:

static class ExtensionMethods
{
    public static Color ToColor(this uint argb)
    {
        return Color.FromArgb((byte)((argb & -16777216)>> 0x18),      
                              (byte)((argb & 0xff0000)>> 0x10),   
                              (byte)((argb & 0xff00) >> 8),
                              (byte)(argb & 0xff));
    }
}

In use:

Color color = 0xFFDFD991.ToColor();

Convert integer to hex and hex to integer

Convert int to hex:

SELECT FORMAT(512+255,'X')

Converting from hex to string

For Unicode support:

public class HexadecimalEncoding
{
    public static string ToHexString(string str)
    {
        var sb = new StringBuilder();

        var bytes = Encoding.Unicode.GetBytes(str);
        foreach (var t in bytes)
        {
            sb.Append(t.ToString("X2"));
        }

        return sb.ToString(); // returns: "48656C6C6F20776F726C64" for "Hello world"
    }

    public static string FromHexString(string hexString)
    {
        var bytes = new byte[hexString.Length / 2];
        for (var i = 0; i < bytes.Length; i++)
        {
            bytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
        }

        return Encoding.Unicode.GetString(bytes); // returns: "Hello world" for "48656C6C6F20776F726C64"
    }
}

Create a hexadecimal colour based on a string with JavaScript

Just porting over the Java from Compute hex color code for an arbitrary string to Javascript:

function hashCode(str) { // java String#hashCode
    var hash = 0;
    for (var i = 0; i < str.length; i++) {
       hash = str.charCodeAt(i) + ((hash << 5) - hash);
    }
    return hash;
} 

function intToRGB(i){
    var c = (i & 0x00FFFFFF)
        .toString(16)
        .toUpperCase();

    return "00000".substring(0, 6 - c.length) + c;
}

To convert you would do:

intToRGB(hashCode(your_string))

Convert string to hex-string in C#

According to this snippet here, this approach should be good for long strings:

private string StringToHex(string hexstring)
{
    StringBuilder sb = new StringBuilder();
    foreach (char t in hexstring)
    { 
        //Note: X for upper, x for lower case letters
        sb.Append(Convert.ToInt32(t).ToString("x")); 
    }
    return sb.ToString();
}

usage:

string result = StringToHex("Hello world"); //returns "48656c6c6f20776f726c64"

Another approach in one line

string input = "Hello world";
string result = String.Concat(input.Select(x => ((int)x).ToString("x")));

Write bytes to file

If I understand you correctly, this should do the trick. You'll need add using System.IO at the top of your file if you don't already have it.

public bool ByteArrayToFile(string fileName, byte[] byteArray)
{
    try
    {
        using (var fs = new FileStream(fileName, FileMode.Create, FileAccess.Write))
        {
            fs.Write(byteArray, 0, byteArray.Length);
            return true;
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine("Exception caught in process: {0}", ex);
        return false;
    }
}

Print a string as hex bytes?

For Python 2.x:

':'.join(x.encode('hex') for x in 'Hello World!')

The code above will not work with Python 3.x, for 3.x, the code below will work:

':'.join(hex(ord(x))[2:] for x in 'Hello World!')

Hex transparency in colors

That chart is not showing percents. "#90" is not "90%". That chart shows the hexadecimal to decimal conversion. The hex number 90 (typically represented as 0x90) is equivalent to the decimal number 144.

Hexadecimal numbers are base-16, so each digit is a value between 0 and F. The maximum value for a two byte hex value (such as the transparency of a color) is 0xFF, or 255 in decimal. Thus 100% is 0xFF.

PHP convert string to hex and hex to string

For people that end up here and are just looking for the hex representation of a (binary) string.

bin2hex("that's all you need");
# 74686174277320616c6c20796f75206e656564

hex2bin('74686174277320616c6c20796f75206e656564');
# that's all you need

Doc: bin2hex, hex2bin.

Convert hexadecimal string (hex) to a binary string

BigInteger.toString(radix) will do what you want. Just pass in a radix of 2.

static String hexToBin(String s) {
  return new BigInteger(s, 16).toString(2);
}

How do you convert a byte array to a hexadecimal string in C?

Solution

Function btox converts arbitrary data *bb to an unterminated string *xp of n hexadecimal digits:

void btox(char *xp, const char *bb, int n) 
{
    const char xx[]= "0123456789ABCDEF";
    while (--n >= 0) xp[n] = xx[(bb[n>>1] >> ((1 - (n&1)) << 2)) & 0xF];
}

Example

#include <stdio.h>

typedef unsigned char uint8;

void main(void) 
{
    uint8 buf[] = {0, 1, 10, 11};
    int n = sizeof buf << 1;
    char hexstr[n + 1];

    btox(hexstr, buf, n);
    hexstr[n] = 0; /* Terminate! */
    printf("%s\n", hexstr);
}

Result: 00010A0B.

Live: Tio.run.

How do I convert hex to decimal in Python?

If by "hex data" you mean a string of the form

s = "6a48f82d8e828ce82b82"

you can use

i = int(s, 16)

to convert it to an integer and

str(i)

to convert it to a decimal string.

Python conversion from binary string to hexadecimal

bstr = '0000 0100 1000 1101'.replace(' ', '')
hstr = '%0*X' % ((len(bstr) + 3) // 4, int(bstr, 2))

Converting an integer to a hexadecimal string in Ruby

Just in case you have a preference for how negative numbers are formatted:

p "%x" % -1   #=> "..f"
p -1.to_s(16) #=> "-1"

Convert hex string to int in Python

Without the 0x prefix, you need to specify the base explicitly, otherwise there's no way to tell:

x = int("deadbeef", 16)

With the 0x prefix, Python can distinguish hex and decimal automatically.

>>> print(int("0xdeadbeef", 0))
3735928559
>>> print(int("10", 0))
10

(You must specify 0 as the base in order to invoke this prefix-guessing behavior; if you omit the second parameter int() will assume base-10.)

How to convert a byte array to a hex string in Java?

  public static byte[] hexStringToByteArray(String s) {
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i < len; i += 2) {
      data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
        + Character.digit(s.charAt(i+1), 16));
    }
  return data;
  } 

What do numbers using 0x notation mean?

It's a hexadecimal number.

0x6400 translates to 4*16^2 + 6*16^3 = 25600

Conversion hex string into ascii in bash command line

This worked for me.

$ echo 54657374696e672031203220330 | xxd -r -p
Testing 1 2 3$

-r tells it to convert hex to ascii as opposed to its normal mode of doing the opposite

-p tells it to use a plain format.

printf() formatting for hex

The "0x" counts towards the eight character count. You need "%#010x".

Note that # does not append the 0x to 0 - the result will be 0000000000 - so you probably actually should just use "0x%08x" anyway.

Ascii/Hex convert in bash

echo -n Aa | hexdump -e '/1 "%02x"'; echo

Hexadecimal to Integer in Java

I finally find answers to my question based on all of your comments. Thanks, I tried this :

public Integer calculateHash(String uuid) {

    try {
        //....
        String hex = hexToString(output);
        //Integer i = Integer.valueOf(hex, 16).intValue();
        //Instead of using Integer, I used BigInteger and I returned the int value.
        BigInteger bi = new BigInteger(hex, 16);
        return bi.intValue();`
    } catch (NoSuchAlgorithmException e) {
        System.out.println("SHA1 not implemented in this system");
    }
    //....
}

This solution is not optimal but I can continue with my project. Thanks again for your help

Convert ascii char[] to hexadecimal char[] in C

#include <stdio.h>
#include <string.h>

int main(void){
    char word[17], outword[33];//17:16+1, 33:16*2+1
    int i, len;

    printf("Intro word:");
    fgets(word, sizeof(word), stdin);
    len = strlen(word);
    if(word[len-1]=='\n')
        word[--len] = '\0';

    for(i = 0; i<len; i++){
        sprintf(outword+i*2, "%02X", word[i]);
    }
    printf("%s\n", outword);
    return 0;
}

How to get a Color from hexadecimal Color String

It's

int color =  Color.parseColor("colorstring");

How to get hex color value rather than RGB value?

my compact version

_x000D_
_x000D_
//Function to convert rgb color to hex format
function rgb2hex(rgb) {
    if(/^#/.test(rgb))return rgb;// if returns colors as hexadecimal
    let re = /\d+/g;
    let hex = x => (x >> 4).toString(16)+(x & 0xf).toString(16);
    return "#"+hex(re.exec(rgb))+hex(re.exec(rgb))+hex(re.exec(rgb));
}
_x000D_
_x000D_
_x000D_

C++ cout hex values?

If you want to print a single hex number, and then revert back to decimal you can use this:

std::cout << std::hex << num << std::dec << std::endl;

How to convert a color integer to a hex String in Android?

Here is what i did

 int color=//your color
 Integer.toHexString(color).toUpperCase();//upercase with alpha
 Integer.toHexString(color).toUpperCase().substring(2);// uppercase without alpha

Thanks guys you answers did the thing

C++ convert string to hexadecimal and vice versa

This is a bit faster:

static const char* s_hexTable[256] = 
{
    "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "0a", "0b", "0c", "0d", "0e", "0f", "10", "11",
    "12", "13", "14", "15", "16", "17", "18", "19", "1a", "1b", "1c", "1d", "1e", "1f", "20", "21", "22", "23",
    "24", "25", "26", "27", "28", "29", "2a", "2b", "2c", "2d", "2e", "2f", "30", "31", "32", "33", "34", "35",
    "36", "37", "38", "39", "3a", "3b", "3c", "3d", "3e", "3f", "40", "41", "42", "43", "44", "45", "46", "47",
    "48", "49", "4a", "4b", "4c", "4d", "4e", "4f", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59",
    "5a", "5b", "5c", "5d", "5e", "5f", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "6a", "6b",
    "6c", "6d", "6e", "6f", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "7a", "7b", "7c", "7d",
    "7e", "7f", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "8a", "8b", "8c", "8d", "8e", "8f",
    "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "9a", "9b", "9c", "9d", "9e", "9f", "a0", "a1",
    "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "aa", "ab", "ac", "ad", "ae", "af", "b0", "b1", "b2", "b3",
    "b4", "b5", "b6", "b7", "b8", "b9", "ba", "bb", "bc", "bd", "be", "bf", "c0", "c1", "c2", "c3", "c4", "c5",
    "c6", "c7", "c8", "c9", "ca", "cb", "cc", "cd", "ce", "cf", "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
    "d8", "d9", "da", "db", "dc", "dd", "de", "df", "e0", "e1", "e2", "e3", "e4", "e5", "e6", "e7", "e8", "e9",
    "ea", "eb", "ec", "ed", "ee", "ef", "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9", "fa", "fb",
    "fc", "fd", "fe", "ff"
};

// Convert binary data sequence [beginIt, endIt) to hexadecimal string
void dataToHexString(const uint8_t*const beginIt, const uint8_t*const endIt, string& str)
{
    str.clear();
    str.reserve((endIt - beginIt) * 2);
    for(const uint8_t* it(beginIt); it != endIt; ++it)
    {
        str += s_hexTable[*it];
    }
}

Java converting int to hex and back again

Try using BigInteger class, it works.

int Val=-32768;
String Hex=Integer.toHexString(Val);

//int FirstAttempt=Integer.parseInt(Hex,16); // Error "Invalid Int"
//int SecondAttempt=Integer.decode("0x"+Hex);  // Error "Invalid Int"
BigInteger i = new BigInteger(Hex,16);
System.out.println(i.intValue());

Integer to hex string in C++

My solution. Only integral types are allowed.

Update. You can set optional prefix 0x in second parameter.

definition.h

#include  <iomanip>
#include <sstream>

template <class T, class T2 = typename std::enable_if<std::is_integral<T>::value>::type>
static std::string ToHex(const T & data, bool addPrefix = true);



template<class T, class>
inline std::string Convert::ToHex(const T & data, bool addPrefix)
{
    std::stringstream sstream;
    sstream << std::hex;
    std::string ret;
    if (typeid(T) == typeid(char) || typeid(T) == typeid(unsigned char) || sizeof(T)==1)
    {
        sstream << static_cast<int>(data);
        ret = sstream.str();
        if (ret.length() > 2)
        {
            ret = ret.substr(ret.length() - 2, 2);
        }
    }
    else
    {
        sstream << data;
        ret = sstream.str();
    }
    return (addPrefix ? u8"0x" : u8"") + ret;
}

main.cpp

#include <definition.h>
int main()
{
    std::cout << ToHex<unsigned char>(254) << std::endl;
    std::cout << ToHex<char>(-2) << std::endl;
    std::cout << ToHex<int>(-2) << std::endl;
    std::cout << ToHex<long long>(-2) << std::endl;

    std::cout<< std::endl;
    std::cout << ToHex<unsigned char>(254, false) << std::endl;
    std::cout << ToHex<char>(-2, false) << std::endl;
    std::cout << ToHex<int>(-2, false) << std::endl;
    std::cout << ToHex<long long>(-2, false) << std::endl;
    return 0;
}

Results:
0xfe
0xfe
0xfffffffe
0xfffffffffffffffe

fe
fe fffffffe
fffffffffffffffe

C++: Converting Hexadecimal to Decimal

#include <iostream>
#include <iomanip>
#include <sstream>

int main()
{
    int x, y;
    std::stringstream stream;

    std::cin >> x;
    stream << x;
    stream >> std::hex >> y;
    std::cout << y;

    return 0;
}

Char array to hex string C++

Here is something:

char const hex_chars[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

for( int i = data; i < data_length; ++i )
{
    char const byte = data[i];

    string += hex_chars[ ( byte & 0xF0 ) >> 4 ];
    string += hex_chars[ ( byte & 0x0F ) >> 0 ];
}

In Java, how do I convert a byte array to a string of hex digits while keeping leading zeros?

A simple approach would be to check how many digits are output by Integer.toHexString() and add a leading zero to each byte if needed. Something like this:

public static String toHexString(byte[] bytes) {
    StringBuilder hexString = new StringBuilder();

    for (int i = 0; i < bytes.length; i++) {
        String hex = Integer.toHexString(0xFF & bytes[i]);
        if (hex.length() == 1) {
            hexString.append('0');
        }
        hexString.append(hex);
    }

    return hexString.toString();
}

Converting A String To Hexadecimal In Java

To go the other way (hex to string), you can use

public String hexToString(String hex) {
    return new String(new BigInteger(hex, 16).toByteArray());
}

Convert a String of Hex into ASCII in Java

So as I understand it, you need to pull out successive pairs of hex digits, then decode that 2-digit hex number and take the corresponding char:

String s = "...";
StringBuilder sb = new StringBuilder(s.length() / 2);
for (int i = 0; i < s.length(); i+=2) {
    String hex = "" + s.charAt(i) + s.charAt(i+1);
    int ival = Integer.parseInt(hex, 16);
    sb.append((char) ival);
}
String string = sb.toString();

How to convert a hex string to hex number

Try this:

hex_str = "0xAD4"
hex_int = int(hex_str, 16)
new_int = hex_int + 0x200
print hex(new_int)

If you don't like the 0x in the beginning, replace the last line with

print hex(new_int)[2:]

Generating a random hex color code with PHP

function random_color(){  
 return sprintf('#%06X', mt_rand(0, 0xFFFFFF));
}

How to create python bytes object from long hex string?

import binascii

binascii.a2b_hex(hex_string)

Thats the way I did it.

Programmatically Lighten or Darken a hex color (or rgb, and blend colors)

I needed it in C#, it may help .net developers

public static string LightenDarkenColor(string color, int amount)
    {
        int colorHex = int.Parse(color, System.Globalization.NumberStyles.HexNumber);
        string output = (((colorHex & 0x0000FF) + amount) | ((((colorHex >> 0x8) & 0x00FF) + amount) << 0x8) | (((colorHex >> 0xF) + amount) << 0xF)).ToString("x6");
        return output;
    }

Convert hex to binary

The binary version of ABC123EFFF is actually 1010101111000001001000111110111111111111

For almost all applications you want the binary version to have a length that is a multiple of 4 with leading padding of 0s.

To get this in Python:

def hex_to_binary( hex_code ):
  bin_code = bin( hex_code )[2:]
  padding = (4-len(bin_code)%4)%4
  return '0'*padding + bin_code

Example 1:

>>> hex_to_binary( 0xABC123EFFF )
'1010101111000001001000111110111111111111'

Example 2:

>>> hex_to_binary( 0x7123 )
'0111000100100011'

Note that this also works in Micropython :)

Get string character by index - Java

CharAt function not working

Edittext.setText(YourString.toCharArray(),0,1);

This code working fine

When and where to use GetType() or typeof()?

typeof is applied to a name of a type or generic type parameter known at compile time (given as identifier, not as string). GetType is called on an object at runtime. In both cases the result is an object of the type System.Type containing meta-information on a type.

Example where compile-time and run-time types are equal

string s = "hello";

Type t1 = typeof(string);
Type t2 = s.GetType();

t1 == t2 ==> true

Example where compile-time and run-time types are different

object obj = "hello";

Type t1 = typeof(object); // ==> object
Type t2 = obj.GetType();  // ==> string!

t1 == t2 ==> false

i.e., the compile time type (static type) of the variable obj is not the same as the runtime type of the object referenced by obj.


Testing types

If, however, you only want to know whether mycontrol is a TextBox then you can simply test

if (mycontrol is TextBox)

Note that this is not completely equivalent to

if (mycontrol.GetType() == typeof(TextBox))    

because mycontrol could have a type that is derived from TextBox. In that case the first comparison yields true and the second false! The first and easier variant is OK in most cases, since a control derived from TextBox inherits everything that TextBox has, probably adds more to it and is therefore assignment compatible to TextBox.

public class MySpecializedTextBox : TextBox
{
}

MySpecializedTextBox specialized = new MySpecializedTextBox();
if (specialized is TextBox)       ==> true

if (specialized.GetType() == typeof(TextBox))        ==> false

Casting

If you have the following test followed by a cast and T is nullable ...

if (obj is T) {
    T x = (T)obj; // The casting tests, whether obj is T again!
    ...
}

... you can change it to ...

T x = obj as T;
if (x != null) {
    ...
}

Testing whether a value is of a given type and casting (which involves this same test again) can both be time consuming for long inheritance chains. Using the as operator followed by a test for null is more performing.

Starting with C# 7.0 you can simplify the code by using pattern matching:

if (obj is T t) {
    // t is a variable of type T having a non-null value.
    ...
}

Btw.: this works for value types as well. Very handy for testing and unboxing. Note that you cannot test for nullable value types:

if (o is int? ni) ===> does NOT compile!

This is because either the value is null or it is an int. This works for int? o as well as for object o = new Nullable<int>(x);:

if (o is int i) ===> OK!

I like it, because it eliminates the need to access the Nullable<T>.Value property.

javac : command not found

I use Fedora (currently 31)

Even with JDK's installed, I still need to specify JAVAC_HOME in the .bashrc, especially since I have 4 Java versions using sudo alternatives --configure java to switch between them.

To find java location of java selected in alternatives

readlink -f $(which java)

In my case: /usr/java/jdk1.8.0_241-amd64/jre/bin/java

So I set following in .bashrc to:

export JAVA_HOME=/usr/java/jdk1.8.0_241-amd64/jre/bin/java

export JAVAC_HOME=/usr/java/jdk1.8.0_241-amd64/bin/javac

export PATH=$PATH:/usr/java/jdk1.8.0_241-amd64/jre/bin

export PATH=$PATH:/usr/java/jdk1.8.0_241-amd64/bin/

Now javac –version gives: javac 1.8.0_241

This is useful for those who want to use Oracle's version. Just remember to change your .bashrc again if you make a change with java alternatives.

Exit a while loop in VBS/VBA

I know this is old as dirt but it ranked pretty high in google.

The problem with the solution maddy implemented (in response to rahul) to maintain the use of a While...Wend loop has some drawbacks

In the example given

num = 0
While num < 10
  If status = "Fail" Then
    num = 10
  End If
  num = num + 1
Wend

After status = "Fail" num will actually equal 11. The loop didn't end on the fail condition, it ends on the next test. All of the code after the check still processed and your counter is not what you might have expected it to be.

Now depending on what you are all doing in your loop it may not matter, but then again if your code looked something more like:

num = 0
While num < 10
  If folder = "System32" Then
    num = 10
  End If
  RecursiveDeleteFunction folder
  num = num + 1
Wend

Using Do While or Do Until allows you to stop execution of the loop using Exit Do instead of using trickery with your loop condition to maintain the While ... Wend syntax. I would recommend using that instead.

java.lang.UnsupportedClassVersionError Unsupported major.minor version 51.0

These guys gave you the reason why is failing but not how to solve it. This problem may appear even if you have a jdk which matches JVM which you are trying it into.

Project -> Properties -> Java Compiler

Enable project specific settings.

Then select Compiler Compliance Level to 1.6 or 1.5, build and test your app.

Now, it should be fine.

Replace special characters in a string with _ (underscore)

string = string.replace(/[&\/\\#,+()$~%.'":*?<>{}]/g,'_');

Alternatively, to change all characters except numbers and letters, try:

string = string.replace(/[^a-zA-Z0-9]/g,'_');

How can I get the intersection, union, and subset of arrays in Ruby?

If Multiset extends from the Array class

x = [1, 1, 2, 4, 7]
y = [1, 2, 2, 2]
z = [1, 1, 3, 7]

UNION

x.union(y)           # => [1, 2, 4, 7]      (ONLY IN RUBY 2.6)
x.union(y, z)        # => [1, 2, 4, 7, 3]   (ONLY IN RUBY 2.6)
x | y                # => [1, 2, 4, 7]

DIFFERENCE

x.difference(y)      # => [4, 7] (ONLY IN RUBY 2.6)
x.difference(y, z)   # => [4] (ONLY IN RUBY 2.6)
x - y                # => [4, 7]

INTERSECTION

x & y                # => [1, 2]

For more info about the new methods in Ruby 2.6, you can check this blog post about its new features

Tool to generate JSON schema from JSON data

json-schema-generator is a neat Ruby based JSON schema generator. It supports both draft 3 and 4 of the JSON schema. It can be run as a standalone executable, or it can be embedded inside of a Ruby script.

Then you can use json-schema to validate JSON samples against your newly generated schema if you want.

Can a Windows batch file determine its own file name?

Bear in mind that 0 is a special case of parameter numbers inside a batch file, where 0 means this file as given on the command line.

So if the file is myfile.bat, you could call it in several ways as follows, each of which would give you a different output from the %0 or %~0 usage:

myfile

myfile.bat

mydir\myfile.bat

c:\mydir\myfile.bat

"c:\mydir\myfile.bat"

All of the above are legal calls if you call it from the correct relative place to the directory in which it exists. %~0 strips the quotes from the last example, whereas %0 does not.

Because these all give different results, %0 and %~0 are very unlikely to be what you actually want to use.

Here's a batch file to illustrate:

@echo Full path and filename: %~f0
@echo Drive: %~d0
@echo Path: %~p0
@echo Drive and path: %~dp0
@echo Filename without extension: %~n0
@echo Filename with    extension: %~nx0
@echo Extension: %~x0
@echo Filename as given on command line: %0
@echo Filename as given on command line minus quotes: %~0
@REM Build from parts
@SETLOCAL
@SET drv=%~d0
@SET pth=%~p0
@SET fpath=%~dp0
@SET fname=%~n0
@SET ext=%~x0
@echo Simply Constructed name: %fpath%%fname%%ext%
@echo Fully  Constructed name: %drv%%pth%%fname%%ext%
@ENDLOCAL
pause

Error: The type exists in both directories

There might be two classes with same name "Helper" in your solution/project. Change name of one of them and then rebuild

To get specific part of a string in c#

Something like this?

string b = a.Split(',')[0];

Get method arguments using Spring AOP?

Your can use either of the following methods.

@Before("execution(* ong.customer.bo.CustomerBo.addCustomer(String))")
public void logBefore1(JoinPoint joinPoint) {
    System.out.println(joinPoint.getArgs()[0]);
 }

or

@Before("execution(* ong.customer.bo.CustomerBo.addCustomer(String)), && args(inputString)")
public void logBefore2(JoinPoint joinPoint, String inputString) {
    System.out.println(inputString);
 }

joinpoint.getArgs() returns object array. Since, input is single string, only one object is returned.

In the second approach, the name should be same in expression and input parameter in the advice method i.e. args(inputString) and public void logBefore2(JoinPoint joinPoint, String inputString)

Here, addCustomer(String) indicates the method with one String input parameter.

Why am I getting this error Premature end of file?

For those who reached this post for Answer:

This happens mainly because the InputStream the DOM parser is consuming is empty

So in what I ran across, there might be two situations:

  1. The InputStream you passed into the parser has been used and thus emptied.
  2. The File or whatever you created the InputStream from may be an empty file or string or whatever. The emptiness might be the reason caused the problem. So you need to check your source of the InputStream.

How do I change the default port (9000) that Play uses when I execute the "run" command?

On windows, I use a start.bat file like this:

java -Dhttp.port=9001 -DapplyEvolutions.default=true -cp "./lib/*;" play.core.server.NettyServer "."

The -DapplyEvolutions.default=true tells evolution to automatically apply evolutions without asking for confirmation. Use with caution on production environment, of course...

Is there a format code shortcut for Visual Studio?

Yes, you can use the two-chord hotkey (Ctrl+K, Ctrl+F if you're using the General profile) to format your selection.

Other formatting options are under menu EditAdvanced, and like all Visual Studio commands, you can set your own hotkey via menu ToolsOptionsEnvironmentKeyboard (the format selection command is called Edit.FormatSelection).

Formatting doesn't do anything with blank lines, but it will indent your code according to some rules that are usually slightly off from what you probably want.

What, why or when it is better to choose cshtml vs aspx?

As other people have answered, .cshtml (or .vbhtml if that's your flavor) provides a handler-mapping to load the MVC engine. The .aspx extension simply loads the aspnet_isapi.dll that performs the compile and serves up web forms. The difference in the handler mapping is simply a method of allowing the two to co-exist on the same server allowing both MVC applications and WebForms applications to live under a common root.

This allows http://www.mydomain.com/MyMVCApplication to be valid and served with MVC rules along with http://www.mydomain.com/MyWebFormsApplication to be valid as a standard web form.

Edit:
As for the difference in the technologies, the MVC (Razor) templating framework is intended to return .Net pages to a more RESTful "web-based" platform of templated views separating the code logic between the model (business/data objects), the view (what the user sees) and the controllers (the connection between the two). The WebForms model (aspx) was an attempt by Microsoft to use complex javascript embedding to simulate a more stateful application similar to a WinForms application complete with events and a page lifecycle that would be capable of retaining its own state from page to page.

The choice to use one or the other is always going to be a contentious one because there are arguments for and against both systems. I for one like the simplicity in the MVC architecture (though routing is anything but simple) and the ease of the Razor syntax. I feel the WebForms architecture is just too heavy to be an effective web platform. That being said, there are a lot of instances where the WebForms framework provides a very succinct and usable model with a rich event structure that is well defined. It all boils down to the needs of the application and the preferences of those building it.

IE7 Z-Index Layering Issues

In IE6 in general, certain UI-elements are implemented with native controls. These controls are rendered in a completely separate phase (window?) and always appear above any other controls, regardless of z-index. Select-boxes are another such problematic control.

The only way to work-around this issue is to construct content which IE renders as a seperate "window" - i.e. you can place a selectbox over a textbox, or, more usefully, an iframe.

In short, you'll need to put "on-hover" like things such as menu's in an iframe in order to let IE place these above built-in UI controls.

This should have been fixed in IE7 (see http://blogs.msdn.com/ie/archive/2006/01/17/514076.aspx) but perhaps you're running in some kind of compatibility mode?

Embedding SVG into ReactJS

There is a package that converts it for you and returns the svg as a string to implement into your reactJS file.

https://www.npmjs.com/package/convert-svg-react

How to repeat last command in python interpreter shell?

On Ubuntu 16.04, I had the same problem after upgrading Python from the preloaded 3.5 to version 3.7 from source code. As @erewok suggested, I did

sudo apt-get install libncurses-dev libreadline-dev

followed by: sudo make install After that, the arrow-up key worked. Not sure which module is required to fix the problem or both, but without "make install", none would work. During initial make, there were some red-flag errors, but ignored and completed the build. This time, there didn't seem to have any errors.

How to SHUTDOWN Tomcat in Ubuntu?

Try using this command : (this will stop tomcat servlet this really helps)

sudo service tomcat7 stop

or

sudo tomcat7 restart (if you need a restart)

How can I insert multiple rows into oracle with a sequence value?

It does not work because sequence does not work in following scenarios:

  • In a WHERE clause
  • In a GROUP BY or ORDER BY clause
  • In a DISTINCT clause
  • Along with a UNION or INTERSECT or MINUS
  • In a sub-query

Source: http://www.orafaq.com/wiki/ORA-02287

However this does work:

insert into table_name
            (col1, col2)
  select my_seq.nextval, inner_view.*
    from (select 'some value' someval
            from dual
          union all
          select 'another value' someval
            from dual) inner_view;

Try it out:

create table table_name(col1 varchar2(100), col2 varchar2(100));

create sequence vcert.my_seq
start with 1
increment by 1
minvalue 0;

select * from  table_name;

How do you use https / SSL on localhost?

It is easy to create a self-signed certificate, import it, and bind it to your website.

1.) Create a self-signed certificate:

Run the following 4 commands, one at a time, from an elevated Command Prompt:

cd C:\Program Files (x86)\Windows Kits\8.1\bin\x64

makecert -r -n "CN=localhost" -b 01/01/2000 -e 01/01/2099 -eku 1.3.6.1.5.5.7.3.3 -sv localhost.pvk localhost.cer

cert2spc localhost.cer localhost.spc

pvk2pfx -pvk localhost.pvk -spc localhost.spc -pfx localhost.pfx

2.) Import certificate to Trusted Root Certification Authorities store:

start --> run --> mmc.exe --> Certificates plugin --> "Trusted Root Certification Authorities" --> Certificates

Right-click Certificates --> All Tasks --> Import Find your "localhost" Certificate at C:\Program Files (x86)\Windows Kits\8.1\bin\x64\

3.) Bind certificate to website:

start --> (IIS) Manager --> Click on your Server --> Click on Sites --> Click on your top level site --> Bindings

Add or edit a binding for https and select the SSL certificate called "localhost".

4.) Import Certificate to Chrome:

Chrome Settings --> Manage Certificates --> Import .pfx certificate from C:\certificates\ folder

Test Certificate by opening Chrome and navigating to https://localhost/

jQuery UI - Draggable is not a function?

4 years after the question got posted, but maybe it will help others who run into this problem. The answer has been posted elsewhere on StackExchange as well, but I lost the link and it's hard to find.

ANSWER: In jQueryTOOLS, the jQuery 'core' is also embedded if you use the default download.

When you load jQuery and jQuery tools, jQuery core gets defined twice and will 'unset' any plugins. 'Draggable' (from jQuery-UI) is such a plug-in.

The solution is to use jQuery tools WITHOUT the jQuery 'core' files and everything will work fine.

Find IP address of directly connected device

Windows 7 has the arp command within it. arp -a should show you the static and dynamic type interfaces connected to your system.

SecurityError: Blocked a frame with origin from accessing a cross-origin frame

I experienced this error when trying to embed an iframe and then opening the site with Brave. The error went away when I changed to "Shields Down" for the site in question. Obviously, this is not a full solution, since anyone else visiting the site with Brave will run into the same issue. To actually resolve it I would need to do one of the other things listed on this page. But at least I now know where the problem lies.

What is the correct syntax of ng-include?

For those who are looking for the shortest possible "item renderer" solution from a partial, so a combo of ng-repeat and ng-include:

<div ng-repeat="item in items" ng-include src="'views/partials/item.html'" />

Actually, if you use it like this for one repeater, it will work, but won't for 2 of them! Angular (v1.2.16) will freak out for some reason if you have 2 of these one after another, so it is safer to close the div the pre-xhtml way:

<div ng-repeat="item in items" ng-include src="'views/partials/item.html'"></div>

How to select element using XPATH syntax on Selenium for Python?

HTML

<div id='a'>
  <div>
    <a class='click'>abc</a>
  </div>
</div>

You could use the XPATH as :

//div[@id='a']//a[@class='click']

output

<a class="click">abc</a>

That said your Python code should be as :

driver.find_element_by_xpath("//div[@id='a']//a[@class='click']")

Handling optional parameters in javascript

Are you saying you can have calls like these: getData(id, parameters); getData(id, callback)?

In this case you can't obviously rely on position and you have to rely on analysing the type: getType() and then if necessary getTypeName()

Check if the parameter in question is an array or a function.

CSS Printing: Avoiding cut-in-half DIVs between pages?

page-break-inside: avoid; gave me trouble using wkhtmltopdf.

To avoid breaks in the text add display: table; to the CSS of the text-containing div.

I hope this works for you too. Thanks JohnS.

Get integer value from string in swift

The method you want is toInt() -- you have to be a little careful, since the toInt() returns an optional Int.

let stringNumber = "1234"
let numberFromString = stringNumber.toInt()
// numberFromString is of type Int? with value 1234

let notANumber = "Uh oh"
let wontBeANumber = notANumber.toInt()
// wontBeANumber is of type Int? with value nil

How to increase an array's length

Arrays in Java are of fixed size that is specified when they are declared. To increase the size of the array you have to create a new array with a larger size and copy all of the old values into the new array.

ex:

char[] copyFrom  = { 'a', 'b', 'c', 'd', 'e' };
char[] copyTo    = new char[7];

System.out.println(Arrays.toString(copyFrom));
System.arraycopy(copyFrom, 0, copyTo, 0, copyFrom.length);
System.out.println(Arrays.toString(copyTo));

Alternatively you could use a dynamic data structure like a List.

LINQ Joining in C# with multiple conditions

If you need not equal object condition use cross join sequences:

var query = from obj1 in set1
from obj2 in set2
where obj1.key1 == obj2.key2 && obj1.key3.contains(obj2.key5) [...conditions...]

Jquery button click() function is not working

You need to use a delegated event handler, as the #add elements dynamically appended won't have the click event bound to them. Try this:

$("#buildyourform").on('click', "#add", function() {
    // your code...
});

Also, you can make your HTML strings easier to read by mixing line quotes:

var fieldWrapper = $('<div class="fieldwrapper" name="field' + intId + '" id="field' + intId + '"/>');

Or even supplying the attributes as an object:

var fieldWrapper = $('<div></div>', { 
    'class': 'fieldwrapper',
    'name': 'field' + intId,
    'id': 'field' + intId
});

Flutter - Wrap text on overflow, like insert ellipsis or fade

You can do it like that

Expanded(
   child: Text(
   'Text',
   overflow: TextOverflow.ellipsis,
   maxLines: 1
   )
)

How to create a sticky footer that plays well with Bootstrap 3

easily set

position:absolute;
bottom:0;
width:100%;

to your .footer

just do it

C# refresh DataGridView when updating or inserted on another form

Create a small function and use it anywhere

public SqlConnection con = "Your connection string"; 
public void gridviewUpdate()
{
    con.Open();
    string select = "SELECT * from table_name";
    SqlDataAdapter da = new SqlDataAdapter(select, con);
    DataSet ds = new DataSet();
    da.Fill(ds, "table_name");
    datagridview.DataSource = ds;
    datagridview.DataMember = "table_name";
    con.Close();
}

How to pass extra variables in URL with WordPress

to add parameter to post urls (to perma-links), i use this:

add_filter( 'post_type_link', 'append_query_string', 10, 2 );
function append_query_string( $url, $post ) 
{
    return add_query_arg('my_pid',$post->ID, $url);
}

output:

http://yoursite.com/pagename?my_pid=12345678

How to copy files from host to Docker container?

Many that find this question may actually have the problem of copying files into a Docker image while it is being created (I did).

In that case, you can use the COPY command in the Dockerfile that you use to create the image.

See the documentation.

How do I send a cross-domain POST request via JavaScript?

I know this is an old question, but I wanted to share my approach. I use cURL as a proxy, very easy and consistent. Create a php page called submit.php, and add the following code:

<?

function post($url, $data) {
$header = array("User-Agent: " . $_SERVER["HTTP_USER_AGENT"], "Content-Type: application/x-www-form-urlencoded");
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_HTTPHEADER, $header);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
$response = curl_exec($curl);
curl_close($curl);
return $response;
}

$url = "your cross domain request here";
$data = $_SERVER["QUERY_STRING"];
echo(post($url, $data));

Then, in your js (jQuery here):

$.ajax({
type: 'POST',
url: 'submit.php',
crossDomain: true,
data: '{"some":"json"}',
dataType: 'json',
success: function(responseData, textStatus, jqXHR) {
    var value = responseData.someKey;
},
error: function (responseData, textStatus, errorThrown) {
    alert('POST failed.');
}
});

How to enable copy paste from between host machine and virtual machine in vmware, virtual machine is ubuntu

Are you talking about drag and drop, when you say copy and paste? If yes, you can also use Rightclick on object on your main computer and click copy. And then you go into the Virtual Machine and Rightclick the position where you want the file to get copied to.

If this doesn't work use the method KaiserM11 explained and get yourselfe VMware Tools like in this Video: https://www.youtube.com/watch?v=McjwI_6BKZY

Hope my answer was helpfull to you and happy coding :D

Changing fonts in ggplot2

You just missed an initialization step I think.

You can see what fonts you have available with the command windowsFonts(). For example mine looks like this when I started looking at this:

> windowsFonts()
$serif
[1] "TT Times New Roman"

$sans
[1] "TT Arial"

$mono
[1] "TT Courier New"

After intalling the package extraFont and running font_import like this (it took like 5 minutes):

library(extrafont)
font_import()
loadfonts(device = "win")

I had many more available - arguable too many, certainly too many to list here.

Then I tried your code:

library(ggplot2)
library(extrafont)
loadfonts(device = "win")

a <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme(text=element_text(size=16,  family="Comic Sans MS"))
print(a)

yielding this:

enter image description here

Update:

You can find the name of a font you need for the family parameter of element_text with the following code snippet:

> names(wf[wf=="TT Times New Roman"])
[1] "serif"

And then:

library(ggplot2)
library(extrafont)
loadfonts(device = "win")

a <- ggplot(mtcars, aes(x=wt, y=mpg)) + geom_point() +
  ggtitle("Fuel Efficiency of 32 Cars") +
  xlab("Weight (x1000 lb)") + ylab("Miles per Gallon") +
  theme(text=element_text(size=16,  family="serif"))
print(a)

yields: enter image description here

Sleep function Visual Basic

This one is much easie.

Threading.Thread.Sleep(3000)

How to force garbage collection in Java?

You can trigger a GC from the command line. This is useful for batch/crontab:

jdk1.7.0/bin/jcmd <pid> GC.run

See :

Downloading a Google font and setting up an offline site that uses it

3 steps:

  1. Download your custom font on Goole Fonts and down load .css file ex: Download http://fonts.googleapis.com/css?family=Open+Sans:400italic,600italic,400,600,300 and save as example.css
  2. Open file you download (example.css). Now you must download all font-face file and save them on fonts directory.
  3. Edit example.css: replace all font-face file to your .css download

Ex:

_x000D_
_x000D_
@font-face {_x000D_
  font-family: 'Open Sans';_x000D_
  font-style: italic;_x000D_
  font-weight: 400;_x000D_
  src: local('Open Sans Italic'), local('OpenSans-Italic'), url(http://fonts.gstatic.com/s/opensans/v14/xjAJXh38I15wypJXxuGMBvZraR2Tg8w2lzm7kLNL0-w.woff2) format('woff2');_x000D_
  unicode-range: U+0460-052F, U+20B4, U+2DE0-2DFF, U+A640-A69F;_x000D_
}
_x000D_
_x000D_
_x000D_

Look at src: -> url. Download http://fonts.gstatic.com/s/opensans/v14/xjAJXh38I15wypJXxuGMBvZraR2Tg8w2lzm7kLNL0-w.woff2 and save to fonts directory. After that change url to all your downloaded file. Now it will be look like

_x000D_
_x000D_
@font-face {_x000D_
  font-family: 'Open Sans';_x000D_
  font-style: italic;_x000D_
  font-weight: 400;_x000D_
  src: local('Open Sans Italic'), local('OpenSans-Italic'), url(fonts/xjAJXh38I15wypJXxuGMBvZraR2Tg8w2lzm7kLNL0-w.woff2) format('woff2');_x000D_
  unicode-range: U+0460-052F, U+20B4, U+2DE0-2DFF, U+A640-A69F;_x000D_
}
_x000D_
_x000D_
_x000D_

** Download all fonts contain .css file Hope it will help u

Convert string to symbol-able in ruby

from: http://ruby-doc.org/core/classes/String.html#M000809

str.intern => symbol
str.to_sym => symbol

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.

"Koala".intern         #=> :Koala
s = 'cat'.to_sym       #=> :cat
s == :cat              #=> true
s = '@cat'.to_sym      #=> :@cat
s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the :xxx notation.

'cat and dog'.to_sym   #=> :"cat and dog"

But for your example ...

"Book Author Title".gsub(/\s+/, "_").downcase.to_sym

should go ;)

How to Call a Function inside a Render in React/Jsx

The fix was at the accepted answer. Yet if someone wants to know why it worked and why the implementation in the SO question didn't work,

First, functions are first class objects in JavaScript. That means they are treated like any other variable. Function can be passed as an argument to other functions, can be returned by another function and can be assigned as a value to a variable. Read more here.

So we use that variable to invoke the function by adding parentheses () at the end.

One thing, If you have a function that returns a funtion and you just need to call that returned function, you can just have double paranthesis when you call the outer function ()().

Why is January month 0 in Java Calendar?

In addition to DannySmurf's answer of laziness, I'll add that it's to encourage you to use the constants, such as Calendar.JANUARY.

Android how to use Environment.getExternalStorageDirectory()

As described in Documentation Environment.getExternalStorageDirectory() :

Environment.getExternalStorageDirectory() Return the primary shared/external storage directory.

This is an example of how to use it reading an image :

String fileName = "stored_image.jpg";
 String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();
 String pathDir = baseDir + "/Android/data/com.mypackage.myapplication/";

 File f = new File(pathDir + File.separator + fileName);

        if(f.exists()){
          Log.d("Application", "The file " + file.getName() + " exists!";
         }else{
          Log.d("Application", "The file no longer exists!";
         }

How to declare a global variable in C++

Declare extern int x; in file.h. And define int x; only in one cpp file.cpp.

How to programmatically modify WCF app.config endpoint address setting?

I use the following code to change the endpoint address in the App.Config file. You may want to modify or remove the namespace before usage.

using System;
using System.Xml;
using System.Configuration;
using System.Reflection;
//...

namespace Glenlough.Generations.SupervisorII
{
    public class ConfigSettings
    {

        private static string NodePath = "//system.serviceModel//client//endpoint";
        private ConfigSettings() { }

        public static string GetEndpointAddress()
        {
            return ConfigSettings.loadConfigDocument().SelectSingleNode(NodePath).Attributes["address"].Value;
        }

        public static void SaveEndpointAddress(string endpointAddress)
        {
            // load config document for current assembly
            XmlDocument doc = loadConfigDocument();

            // retrieve appSettings node
            XmlNode node = doc.SelectSingleNode(NodePath);

            if (node == null)
                throw new InvalidOperationException("Error. Could not find endpoint node in config file.");

            try
            {
                // select the 'add' element that contains the key
                //XmlElement elem = (XmlElement)node.SelectSingleNode(string.Format("//add[@key='{0}']", key));
                node.Attributes["address"].Value = endpointAddress;

                doc.Save(getConfigFilePath());
            }
            catch( Exception e )
            {
                throw e;
            }
        }

        public static XmlDocument loadConfigDocument()
        {
            XmlDocument doc = null;
            try
            {
                doc = new XmlDocument();
                doc.Load(getConfigFilePath());
                return doc;
            }
            catch (System.IO.FileNotFoundException e)
            {
                throw new Exception("No configuration file found.", e);
            }
        }

        private static string getConfigFilePath()
        {
            return Assembly.GetExecutingAssembly().Location + ".config";
        }
    }
}

How to get the <td> in HTML tables to fit content, and let a specific <td> fill in the rest

demo - http://jsfiddle.net/victor_007/ywevz8ra/

added border for better view (testing)

more info about white-space

table{
    width:100%;
}
table td{
    white-space: nowrap;  /** added **/
}
table td:last-child{
    width:100%;
}

_x000D_
_x000D_
    table {_x000D_
      width: 100%;_x000D_
    }_x000D_
    table td {_x000D_
      white-space: nowrap;_x000D_
    }_x000D_
    table td:last-child {_x000D_
      width: 100%;_x000D_
    }
_x000D_
<table border="1">_x000D_
  <thead>_x000D_
    <tr>_x000D_
      <th>Column A</th>_x000D_
      <th>Column B</th>_x000D_
      <th>Column C</th>_x000D_
      <th class="absorbing-column">Column D</th>_x000D_
    </tr>_x000D_
  </thead>_x000D_
  <tbody>_x000D_
    <tr>_x000D_
      <td>Data A.1 lorem</td>_x000D_
      <td>Data B.1 ip</td>_x000D_
      <td>Data C.1 sum l</td>_x000D_
      <td>Data D.1</td>_x000D_
    </tr>_x000D_
    <tr>_x000D_
      <td>Data A.2 ipsum</td>_x000D_
      <td>Data B.2 lorem</td>_x000D_
      <td>Data C.2 some data</td>_x000D_
      <td>Data D.2 a long line of text that is long</td>_x000D_
    </tr>_x000D_
    <tr>_x000D_
      <td>Data A.3</td>_x000D_
      <td>Data B.3</td>_x000D_
      <td>Data C.3</td>_x000D_
      <td>Data D.3</td>_x000D_
    </tr>_x000D_
  </tbody>_x000D_
</table>
_x000D_
_x000D_
_x000D_

How to use null in switch

You can't. You can use primitives (int, char, short, byte) and String (Strings in java 7 only) in switch. primitives can't be null.
Check i in separate condition before switch.

CMake complains "The CXX compiler identification is unknown"

Run apt-get install build-essential on your system.

This package depends on other packages considered to be essential for builds and will install them. If you find you have to build packages, this can be helpful to avoid piecemeal resolution of dependencies.

See this page for more info.

Update a submodule to the latest commit

Since git 1.8 you can do

git submodule update --remote --merge

This will update the submodule to the latest remote commit. You will then need to commit the change so the gitlink in the parent repository is updated

git commit

And then push the changes as without this, the SHA-1 identity the pointing to the submodule won't be updated and so the change won't be visible to anyone else.

Best practice when adding whitespace in JSX

If the goal is to seperate two elements, you can use CSS like below:

A<span style={{paddingLeft: '20px'}}>B</span>

selecting unique values from a column

DISTINCT is always a right choice to get unique values. Also you can do it alternatively without using it. That's GROUP BY. Which has simply add at the end of the query and followed by the column name.

SELECT * FROM buy GROUP BY date,description

How to convert int to QString?

I always use QString::setNum().

int i = 10;
double d = 10.75;
QString str;
str.setNum(i);
str.setNum(d);

setNum() is overloaded in many ways. See QString class reference.

Using GregorianCalendar with SimpleDateFormat

Why such complications?

public static GregorianCalendar convertFromDMY(String dd_mm_yy) throws ParseException 
{
    SimpleDateFormat fmt = new SimpleDateFormat("dd-MMM-yyyy");
    Date date = fmt.parse(dd_mm_yy);
    GregorianCalendar cal = GregorianCalendar.getInstance();
    cal.setTime(date);
    return cal;
}

TypeError: 'NoneType' object has no attribute '__getitem__'

BrenBarn is correct. The error means you tried to do something like None[5]. In the backtrace, it says self.imageDef=self.values[2], which means that your self.values is None.

You should go through all the functions that update self.values and make sure you account for all the corner cases.

convert HTML ( having Javascript ) to PDF using JavaScript

You can do it using a jquery,

Use this code to link the button...

$(document).ready(function() {
    $("#button_id").click(function() {
        window.print();
        return false;
    });
});

This link may be also helpful: jQuery Print HTML Pdf Page Options Link

How to verify static void method has been called with power mockito

Thou the above answer is widely accepted and well documented, I found some of the reason to post my answer here :-

    doNothing().when(InternalUtils.class); //This is the preferred way
                                           //to mock static void methods.
    InternalUtils.sendEmail(anyString(), anyString(), anyString(), anyString());

Here, I dont understand why we are calling InternalUtils.sendEmail ourself. I will explain in my code why we don't need to do that.

mockStatic(Internalutils.class);

So, we have mocked the class which is fine. Now, lets have a look how we need to verify the sendEmail(/..../) method.

@PrepareForTest({InternalService.InternalUtils.class})
@RunWith(PowerMockRunner.class)
public class InternalServiceTest {

    @Mock
    private InternalService.Order order;

    private InternalService internalService;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        internalService = new InternalService();
    }

    @Test
    public void processOrder() throws Exception {

        Mockito.when(order.isSuccessful()).thenReturn(true);
        PowerMockito.mockStatic(InternalService.InternalUtils.class);

        internalService.processOrder(order);

        PowerMockito.verifyStatic(times(1));
        InternalService.InternalUtils.sendEmail(anyString(), any(String[].class), anyString(), anyString());
    }

}

These two lines is where the magic is, First line tells the PowerMockito framework that it needs to verify the class it statically mocked. But which method it need to verify ?? Second line tells which method it needs to verify.

PowerMockito.verifyStatic(times(1));
InternalService.InternalUtils.sendEmail(anyString(), any(String[].class), anyString(), anyString());

This is code of my class, sendEmail api twice.

public class InternalService {

    public void processOrder(Order order) {
        if (order.isSuccessful()) {
            InternalUtils.sendEmail("", new String[1], "", "");
            InternalUtils.sendEmail("", new String[1], "", "");
        }
    }

    public static class InternalUtils{

        public static void sendEmail(String from, String[]  to, String msg, String body){

        }

    }

    public class Order{

        public boolean isSuccessful(){
            return true;
        }

    }

}

As it is calling twice you just need to change the verify(times(2))... that's all.

Add JavaScript object to JavaScript object

jsonIssues = [...jsonIssues,{ID:'3',Name:'name 3',Notes:'NOTES 3'}]

What is the best way to implement nested dictionaries?

Unless your dataset is going to stay pretty small, you might want to consider using a relational database. It will do exactly what you want: make it easy to add counts, selecting subsets of counts, and even aggregate counts by state, county, occupation, or any combination of these.

Selenium Webdriver submit() vs click()

Also, correct me if I'm wrong, but I believe that submit will wait for a new page to load, whereas click will immediately continue executing code

Find and replace - Add carriage return OR Newline

If you set "Use regular expressions" flag then \n would be translated. But keep in mind that you would have to modify you search term to be regexp friendly. In your case it should be escaped like this "\~\~\?" (no quotes).

javax.net.ssl.SSLException: Read error: ssl=0x9524b800: I/O error during system call, Connection reset by peer

Recently I faced the issue while working on some legacy code. After googling I found that the issue is everywhere but without any concrete resolution. I worked on various parts of the exception message and analyzed below.

Analysis:

  1. SSLException: exception happened with the SSL (Secure Socket Layer), which is implemented in javax.net.ssl package of the JDK (openJDK/oracleJDK/AndroidSDK)
  2. Read error ssl=# I/O error during system call: Error occured while reading from the Secure socket. It happened while using the native system libraries/driver. Please note that all the platforms solaris, Windows etc. have their own socket libraries which is used by the SSL. Windows uses WINSOCK library.
  3. Connection reset by peer: This message is reported by the system library (Solaris reports ECONNRESET, Windows reports WSAECONNRESET), that the socket used in the data transfer is no longer usable because an existing connection was forcibly closed by the remote host. One needs to create a new secure path between the host and client

Reason:

Understanding the issue, I try finding the reason behind the connection reset and I came up with below reasons:

  • The peer application on the remote host is suddenly stopped, the host is rebooted, the host or remote network interface is disabled, or the remote host uses a hard close.
  • This error may also result if a connection was broken due to keep-alive activity detecting a failure while one or more operations are in progress. Operations that were in progress fail with Network dropped connection on reset(On Windows(WSAENETRESET)) and Subsequent operations fail withConnection reset by peer(On Windows(WSAECONNRESET)).
  • If the target server is protected by Firewall, which is true in most of the cases, the Time to live (TTL) or timeout associated with the port forcibly closes the idle connection at given timeout. this is something of our interest

Resolution:

  1. Events on the server side such as sudden service stop, rebooted, network interface disabled can not be handled by any means.
  2. On the server side, Configure firewall for the given port with the higher Time to Live (TTL) or timeout values such as 3600 secs.
  3. Clients can "try" keeping the network active to avoid or reduce the Connection reset by peer.
  4. Normally on going network traffic keeps the connection alive and problem/exception is not seen frequently. Strong Wifi has least chances of Connection reset by peer.
  5. With the mobile networks 2G, 3G and 4G where the packet data delivery is intermittent and dependent on the mobile network availability, it may not reset the TTL timer on the server side and results into the Connection reset by peer.

Here are the terms suggested to set on various forums to resolve the issue

  • ConnectionTimeout: Used only at the time out making the connection. If host takes time to connection higher value of this makes the client wait for the connection.
  • SoTimeout: Socket timeout-It says the maximum time within which the a data packet is received to consider the connection as active.If no data received within the given time, the connection is assumed as stalled/broken.
  • Linger: Upto what time the socket should not be closed when data is queued to be sent and the close socket function is called on the socket.
  • TcpNoDelay: Do you want to disable the buffer that holds and accumulates the TCP packets and send them once a threshold is reached? Setting this to true will skip the TCP buffering so that every request is sent immediately. Slowdowns in the network may be caused by an increase in network traffic due to smaller and more frequent packet transmission.

So none of the above parameter helps keeping the network alive and thus ineffective.

I found one setting that may help resolving the issue which is this functions

setKeepAlive(true)
setSoKeepalive(HttpParams params, enableKeepalive="true") 

How did I resolve my issue?

  • Set the HttpConnectionParams.setSoKeepAlive(params, true)
  • Catch the SSLException and check for the exception message for Connection reset by peer
  • If exception is found, store the download/read progress and create a new connection.
  • If possible resume the download/read else restart the download

I hope the details help. Happy Coding...

Remove white space above and below large text in an inline-block element

The best way is to use display:

inline-block; 

and

overflow: hidden;

Checking if a date is valid in javascript

Try this:

var date = new Date();
console.log(date instanceof Date && !isNaN(date.valueOf()));

This should return true.

UPDATED: Added isNaN check to handle the case commented by Julian H. Lam

Merging 2 branches together in GIT

merge is used to bring two (or more) branches together.

a little example:

# on branch A:
# create new branch B
$ git checkout -b B
# hack hack
$ git commit -am "commit on branch B"

# create new branch C from A
$ git checkout -b C A
# hack hack
$ git commit -am "commit on branch C"

# go back to branch A
$ git checkout A
# hack hack
$ git commit -am "commit on branch A"

so now there are three separate branches (namely A B and C) with different heads

to get the changes from B and C back to A, checkout A (already done in this example) and then use the merge command:

# create an octopus merge
$ git merge B C

your history will then look something like this:

…-o-o-x-------A
      |\     /|
      | B---/ |
       \     /
        C---/

if you want to merge across repository/computer borders, have a look at git pull command, e.g. from the pc with branch A (this example will create two new commits):

# pull branch B
$ git pull ssh://host/… B
# pull branch C
$ git pull ssh://host/… C

how to convert milliseconds to date format in android?

fun convertLongToTimeWithLocale(){
    val dateAsMilliSecond: Long = 1602709200000
    val date = Date(dateAsMilliSecond)
    val language = "en"
    val formattedDateAsDigitMonth = SimpleDateFormat("dd/MM/yyyy", Locale(language))
    val formattedDateAsShortMonth = SimpleDateFormat("dd MMM yyyy", Locale(language))
    val formattedDateAsLongMonth = SimpleDateFormat("dd MMMM yyyy", Locale(language))
    Log.d("month as digit", formattedDateAsDigitMonth.format(date))
    Log.d("month as short", formattedDateAsShortMonth.format(date))
    Log.d("month as long", formattedDateAsLongMonth.format(date))
}

output:

month as digit: 15/10/2020
month as short: 15 Oct 2020 
month as long : 15 October 2020

You can change the value defined as 'language' due to your require. Here is the all language codes: Java language codes

How do I iterate over the words of a string?

The STL does not have such a method available already.

However, you can either use C's strtok() function by using the std::string::c_str() member, or you can write your own. Here is a code sample I found after a quick Google search ("STL string split"):

void Tokenize(const string& str,
              vector<string>& tokens,
              const string& delimiters = " ")
{
    // Skip delimiters at beginning.
    string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    // Find first "non-delimiter".
    string::size_type pos     = str.find_first_of(delimiters, lastPos);

    while (string::npos != pos || string::npos != lastPos)
    {
        // Found a token, add it to the vector.
        tokens.push_back(str.substr(lastPos, pos - lastPos));
        // Skip delimiters.  Note the "not_of"
        lastPos = str.find_first_not_of(delimiters, pos);
        // Find next "non-delimiter"
        pos = str.find_first_of(delimiters, lastPos);
    }
}

Taken from: http://oopweb.com/CPP/Documents/CPPHOWTO/Volume/C++Programming-HOWTO-7.html

If you have questions about the code sample, leave a comment and I will explain.

And just because it does not implement a typedef called iterator or overload the << operator does not mean it is bad code. I use C functions quite frequently. For example, printf and scanf both are faster than std::cin and std::cout (significantly), the fopen syntax is a lot more friendly for binary types, and they also tend to produce smaller EXEs.

Don't get sold on this "Elegance over performance" deal.

Explaining the 'find -mtime' command

To find all files modified in the last 24 hours use the one below. The -1 here means changed 1 day or less ago.

find . -mtime -1 -ls

ActionBarCompat: java.lang.IllegalStateException: You need to use a Theme.AppCompat

Your Activity is extending ActionBarActivity which requires the AppCompat.theme to be applied. Change from ActionBarActivity to Activity or FragmentActivity, it will solve the problem.

Pass a PHP variable value through an HTML form

EDIT: After your comments, I understand that you want to pass variable through your form.

You can do this using hidden field:

<input type='hidden' name='var' value='<?php echo "$var";?>'/> 

In PHP action File:

<?php 
   if(isset($_POST['var'])) $var=$_POST['var'];
?>

Or using sessions: In your first page:

 $_SESSION['var']=$var;

start_session(); should be placed at the beginning of your php page.

In PHP action File:

if(isset($_SESSION['var'])) $var=$_SESSION['var'];

First Answer:

You can also use $GLOBALS :

if (isset($_POST['save_exit']))
{

   echo $GLOBALS['var']; 

}

Check this documentation for more informations.

How to empty (clear) the logcat buffer in Android

For anyone coming to this question wondering how to do this in Eclipse, You can remove the displayed text from the logCat using the button provided (often has a red X on the icon)

Difference between <? super T> and <? extends T> in Java

The generic wildcards target two primary needs:

Reading from a generic collection Inserting into a generic collection There are three ways to define a collection (variable) using generic wildcards. These are:

List<?>           listUknown = new ArrayList<A>();
List<? extends A> listUknown = new ArrayList<A>();
List<? super   A> listUknown = new ArrayList<A>();

List<?> means a list typed to an unknown type. This could be a List<A>, a List<B>, a List<String> etc.

List<? extends A> means a List of objects that are instances of the class A, or subclasses of A (e.g. B and C). List<? super A> means that the list is typed to either the A class, or a superclass of A.

Read more : http://tutorials.jenkov.com/java-generics/wildcards.html

Github Windows 'Failed to sync this branch'

This is probably an edge case, but every time I've got this specific error it is because I've recently mapped a drive in Windows, and powershell cannot find it.

A computer restart (of all things) fixes the error for me, as powershell can now pick up the newly mapped drive. Just make sure you connect to the mapped drive BEFORE opening the github client.

Python conditional assignment operator

No, not knowing which variables are defined is a bug, not a feature in Python.

Use dicts instead:

d = {}
d.setdefault('key', 1)
d['key'] == 1

d['key'] = 2
d.setdefault('key', 1)
d['key'] == 2

Using Intent in an Android application to show another activity

Intent i = new Intent("com.Android.SubActivity");
startActivity(i);

Can't connect to local MySQL server through socket '/tmp/mysql.sock

# shell script ,ignore the first 
$ $(dirname `which mysql`)\/mysql.server start

May be helpful.

Select method of Range class failed via VBA

The correct answer to this particular questions is "don't select". Sometimes you have to select or activate, but 99% of the time you don't. If your code looks like

Select something
Do something to the selection
Select something else
Do something to the selection

You probably need to refactor and consider not selecting.

The error, Method 'Range' of object '_Worksheet' failed, error 1004, that you're getting is because the sheet with the button on it doesn't have a range named "Result". Most (maybe all) properties that return an object have a default Parent object. In this case, you're using the Range property to return a Range object. Because you don't qualify the Range property, Excel uses the default.

The default Parent object can be different based on the circumstances. If your code were in a standard module, then the ActiveSheet would be the default Parent and Excel would try to resolve ActiveSheet.Range("Result"). Your code is in a sheet's class module (the sheet with the button on it). When the unqualified reference is used there, the default Parent is the sheet that's attached to that module. In this case they're the same because the sheet has to be active to click the button, but that isn't always the case.

When Excel gives the error that includes text like '_Object' (yours said '_Worksheet') it's always referring to the default Parent object - the underscore gives that away. Generally the way to fix that is to qualify the reference by being explicit about the parent. But in the case of selecting and activating when you don't need to, it's better to just refactor the code.

Here's one way to write your code without any selecting or activating.

Private Sub cmdRecord_Click()

    Dim shSource As Worksheet
    Dim shDest As Worksheet
    Dim rNext As Range

    'Me refers to the sheet whose class module you're in
    'Me.Parent refers to the workbook
    Set shSource = Me.Parent.Worksheets("BxWsn Simulation")
    Set shDest = Me.Parent.Worksheets("Reslt Record")

    Set rNext = shDest.Cells(shDest.Rows.Count, 1).End(xlUp).Offset(1, 0)

    shSource.Range("Result").Copy
    rNext.PasteSpecial xlPasteFormulasAndNumberFormats

    Application.CutCopyMode = False

End Sub

When I'm in a class module, like the sheet's class module that you're working in, I always try to do things in terms of that class. So I use Me.Parent instead of ActiveWorkbook. It makes the code more portable and prevents unexpected problems when things change.

I'm sure the code you have now runs in milliseconds, so you may not care, but avoiding selecting will definitely speed up your code and you don't have to set ScreenUpdating. That may become important as your code grows or in a different situation.

Data binding for TextBox

You can't databind to a property and then explictly assign a value to the databound property.

how to empty recyclebin through command prompt?

while

rd /s /q %systemdrive%\$RECYCLE.BIN

will delete the $RECYCLE.BIN folder from the system drive, which is usually c:, one should consider deleting it from any other available partitions since there's an hidden $RECYCLE.BIN folder in any partition in local and external drives (but not in removable drives, like USB flash drive, which don't have a $RECYCLE.BIN folder). For example, I installed a program in d:, in order to delete the files it moved to the Recycle Bin I should run:

rd /s /q d:\$RECYCLE.BIN

More information available at Super User at Empty recycling bin from command line

"Conversion to Dalvik format failed with error 1" on external JAR

I am using Android 1.6 and had one external JAR file. What worked for me was to remove all libraries, right-click project and select Android Tools -> *Fix Project Properties (which added back Android 1.6) and then add back the external JAR file.

How to convert Javascript datetime to C# datetime?

DateTime.Parse is a much better bet. JS dates and C# dates do not start from the same root.

Sample:

DateTime dt = DateTime.ParseExact("Tue Jul 12 2011 16:00:00 GMT-0700",
                                  "ddd MMM d yyyy HH:mm:ss tt zzz",
                                  CultureInfo.InvariantCulture);

Regular expression for matching latitude/longitude coordinates?

This one will strictly match latitude and longitude values that fall within the correct range:

^[-+]?([1-8]?\d(\.\d+)?|90(\.0+)?),\s*[-+]?(180(\.0+)?|((1[0-7]\d)|([1-9]?\d))(\.\d+)?)$

Matches

  • +90.0, -127.554334
  • 45, 180
  • -90, -180
  • -90.000, -180.0000
  • +90, +180
  • 47.1231231, 179.99999999

Doesn't Match

  • -90., -180.
  • +90.1, -100.111
  • -91, 123.456
  • 045, 180

Convert Pandas column containing NaNs to dtype `int`

Assuming your DateColumn formatted 3312018.0 should be converted to 03/31/2018 as a string. And, some records are missing or 0.

df['DateColumn'] = df['DateColumn'].astype(int)
df['DateColumn'] = df['DateColumn'].astype(str)
df['DateColumn'] = df['DateColumn'].apply(lambda x: x.zfill(8))
df.loc[df['DateColumn'] == '00000000','DateColumn'] = '01011980'
df['DateColumn'] = pd.to_datetime(df['DateColumn'], format="%m%d%Y")
df['DateColumn'] = df['DateColumn'].apply(lambda x: x.strftime('%m/%d/%Y'))

C# Linq Group By on multiple columns

var consolidatedChildren =
    from c in children
    group c by new
    {
        c.School,
        c.Friend,
        c.FavoriteColor,
    } into gcs
    select new ConsolidatedChild()
    {
        School = gcs.Key.School,
        Friend = gcs.Key.Friend,
        FavoriteColor = gcs.Key.FavoriteColor,
        Children = gcs.ToList(),
    };

var consolidatedChildren =
    children
        .GroupBy(c => new
        {
            c.School,
            c.Friend,
            c.FavoriteColor,
        })
        .Select(gcs => new ConsolidatedChild()
        {
            School = gcs.Key.School,
            Friend = gcs.Key.Friend,
            FavoriteColor = gcs.Key.FavoriteColor,
            Children = gcs.ToList(),
        });

SignalR - Sending a message to a specific user using (IUserIdProvider) *NEW 2.0.0*

For anyone trying to do this in asp.net core. You can use claims.

public class CustomEmailProvider : IUserIdProvider
{
    public virtual string GetUserId(HubConnectionContext connection)
    {
        return connection.User?.FindFirst(ClaimTypes.Email)?.Value;
    }
}

Any identifier can be used, but it must be unique. If you use a name identifier for example, it means if there are multiple users with the same name as the recipient, the message would be delivered to them as well. I have chosen email because it is unique to every user.

Then register the service in the startup class.

services.AddSingleton<IUserIdProvider, CustomEmailProvider>();

Next. Add the claims during user registration.

var result = await _userManager.CreateAsync(user, Model.Password);
if (result.Succeeded)
{
    await _userManager.AddClaimAsync(user, new Claim(ClaimTypes.Email, Model.Email));
}

To send message to the specific user.

public class ChatHub : Hub
{
    public async Task SendMessage(string receiver, string message)
    {
        await Clients.User(receiver).SendAsync("ReceiveMessage", message);
    }
}

Note: The message sender won't be notified the message is sent. If you want a notification on the sender's end. Change the SendMessage method to this.

public async Task SendMessage(string sender, string receiver, string message)
{
    await Clients.Users(sender, receiver).SendAsync("ReceiveMessage", message);
}

These steps are only necessary if you need to change the default identifier. Otherwise, skip to the last step where you can simply send messages by passing userIds or connectionIds to SendMessage. For more

How to parse JSON in Kotlin?

Without external library (on Android)

To parse this:

val jsonString = """
    {
       "type":"Foo",
       "data":[
          {
             "id":1,
             "title":"Hello"
          },
          {
             "id":2,
             "title":"World"
          }
       ]
    }        
"""

Use these classes:

import org.json.JSONObject

class Response(json: String) : JSONObject(json) {
    val type: String? = this.optString("type")
    val data = this.optJSONArray("data")
            ?.let { 0.until(it.length()).map { i -> it.optJSONObject(i) } } // returns an array of JSONObject
            ?.map { Foo(it.toString()) } // transforms each JSONObject of the array into Foo
}

class Foo(json: String) : JSONObject(json) {
    val id = this.optInt("id")
    val title: String? = this.optString("title")
}

Usage:

val foos = Response(jsonString)

How to lock specific cells but allow filtering and sorting

This is a very old, but still very useful thread. I came here recently with the same issue. I suggest protecting the sheet when appropriate and unprotecting it when the filter row (eg Row 1) is selected. My solution doesn't use password protection - I don't need it (its a safeguard, not a security feature). I can't find an event handler that recognizes selection of a filter button - so I gave the instruction to my users to first select the filter cell then click the filter button. Here's what I advocate, (I only change protection if it needs to be changed, that may or may not save time - I don't know, but it "feels" right):

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
  Const FilterRow = 1
  Dim c As Range
  Dim NotFilterRow As Boolean
  Dim oldstate As Boolean
  Dim ws As Worksheet
  Set ws = ActiveSheet
  oldstate = ws.ProtectContents
  NotFilterRow = False
  For Each c In Target.Cells
     NotFilterRow = c.Row <> FilterRow
     If NotFilterRow Then Exit For
  Next c
  If NotFilterRow <> oldstate Then
     If NotFilterRow Then
        ws.Protect
     Else
        ws.Unprotect
     End If
  End If
  Set ws = Nothing
End Sub

"getaddrinfo failed", what does that mean?

May be this will help some one. I have my proxy setup in python script but keep getting the error mentioned in the question.

Below is the piece of block which will take my username and password as a constant in the beginning.

   if (use_proxy):
        proxy = req.ProxyHandler({'https': proxy_url})
        auth = req.HTTPBasicAuthHandler()
        opener = req.build_opener(proxy, auth, req.HTTPHandler)
        req.install_opener(opener)

If you are using corporate laptop and if you did not connect to Direct Access or office VPN then the above block will throw error. All you need to do is to connect to your org VPN and then execute your python script.

Thanks

SFTP Libraries for .NET

I've searched around and found that this fork of SharpSSH and SSH.NET are the most up to date and best maintained libraries for SFTP (not to be confused with FTPS) communication in .NET. SSH.NET is a clean .NET 4.0 implementation of the SFTP protocol, and I've used it in a couple of solutions with flying colors and great success.

The original SharpSsh seems to be dead and most other solutions either require installation of Windows executables or a bucketload of cash (or worse; both).

Drop multiple tables in one shot in MySQL

Example:

Let's say table A has two children B and C. Then we can use the following syntax to drop all tables.

DROP TABLE IF EXISTS B,C,A;

This can be placed in the beginning of the script instead of individually dropping each table.

Changing Vim indentation behavior by file type

This might be known by most of us, but anyway (I was puzzled my first time): Doing :set et (:set expandtabs) does not change the tabs already existing in the file, one has to do :retab. For example:

:set et
:retab

and the tabs in the file are replaced by enough spaces. To have tabs back simply do:

:set noet
:retab

Duplicating a MySQL table, indices, and data

Go to phpMyAdmin and select your original table then select "Operations" tab in the "Copy table to (database.table)" area. Select the database where you want to copy and add a name for your new table.

copy table - phyMyAdmin Screenshot

Why am I getting the error "connection refused" in Python? (Sockets)

host = socket.gethostname()  # Get the local machine name
port = 12397                 # Reserve a port for your service
s.bind((host,port))          # Bind to the port

I think this error may related to the DNS resolution. This sentence host = socket.gethostname() get the host name, but if the operating system can not resolve the host name to local address, you would get the error. Linux operating system can modify the /etc/hosts file, add one line in it. It looks like below( 'hostname' is which socket.gethostname() got).

127.0.0.1   hostname

JAX-RS / Jersey how to customize error handling?

There are several approaches to customize the error handling behavior with JAX-RS. Here are three of the easier ways.

The first approach is to create an Exception class that extends WebApplicationException.

Example:

public class NotAuthorizedException extends WebApplicationException {
     public NotAuthorizedException(String message) {
         super(Response.status(Response.Status.UNAUTHORIZED)
             .entity(message).type(MediaType.TEXT_PLAIN).build());
     }
}

And to throw this newly create Exception you simply:

@Path("accounts/{accountId}/")
    public Item getItem(@PathParam("accountId") String accountId) {
       // An unauthorized user tries to enter
       throw new NotAuthorizedException("You Don't Have Permission");
}

Notice, you don't need to declare the exception in a throws clause because WebApplicationException is a runtime Exception. This will return a 401 response to the client.

The second and easier approach is to simply construct an instance of the WebApplicationException directly in your code. This approach works as long as you don't have to implement your own application Exceptions.

Example:

@Path("accounts/{accountId}/")
public Item getItem(@PathParam("accountId") String accountId) {
   // An unauthorized user tries to enter
   throw new WebApplicationException(Response.Status.UNAUTHORIZED);
}

This code too returns a 401 to the client.

Of course, this is just a simple example. You can make the Exception much more complex if necessary, and you can generate what ever http response code you need to.

One other approach is to wrap an existing Exception, perhaps an ObjectNotFoundException with an small wrapper class that implements the ExceptionMapper interface annotated with a @Provider annotation. This tells the JAX-RS runtime, that if the wrapped Exception is raised, return the response code defined in the ExceptionMapper.

Copying text to the clipboard using Java

This works for me and is quite simple:

Import these:

import java.awt.datatransfer.StringSelection;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;

And then put this snippet of code wherever you'd like to alter the clipboard:

String myString = "This text will be copied into clipboard";
StringSelection stringSelection = new StringSelection(myString);
Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
clipboard.setContents(stringSelection, null);

SELECT only rows that contain only alphanumeric characters in MySQL

Your statement matches any string that contains a letter or digit anywhere, even if it contains other non-alphanumeric characters. Try this:

SELECT * FROM table WHERE column REGEXP '^[A-Za-z0-9]+$';

^ and $ require the entire string to match rather than just any portion of it, and + looks for 1 or more alphanumberic characters.

You could also use a named character class if you prefer:

SELECT * FROM table WHERE column REGEXP '^[[:alnum:]]+$';

NodeJs : TypeError: require(...) is not a function

I think this means that module.exports in your ./app/routes module is not assigned to be a function so therefore require('./app/routes') does not resolve to a function so therefore, you cannot call it as a function like this require('./app/routes')(app, passport).

Show us ./app/routes if you want us to comment further on that.

It should look something like this;

module.exports = function(app, passport) {
    // code here
}

You are exporting a function that can then be called like require('./app/routes')(app, passport).


One other reason a similar error could occur is if you have a circular module dependency where module A is trying to require(B) and module B is trying to require(A). When this happens, it will be detected by the require() sub-system and one of them will come back as null and thus trying to call that as a function will not work. The fix in that case is to remove the circular dependency, usually by breaking common code into a third module that both can separately load though the specifics of fixing a circular dependency are unique for each situation.

Aren't promises just callbacks?

JavaScript Promises actually use callback functions to determine what to do after a Promise has been resolved or rejected, therefore both are not fundamentally different. The main idea behind Promises is to take callbacks - especially nested callbacks where you want to perform a sort of actions, but it would be more readable.

How to write a Python module/package?

Make a file named "hello.py"

If you are using Python 2.x

def func():
    print "Hello"

If you are using Python 3.x

def func():
    print("Hello")

Run the file. Then, you can try the following:

>>> import hello
>>> hello.func()
Hello

If you want a little bit hard, you can use the following:

If you are using Python 2.x

def say(text):
    print text

If you are using Python 3.x

def say(text):
    print(text)

See the one on the parenthesis beside the define? That is important. It is the one that you can use within the define.

Text - You can use it when you want the program to say what you want. According to its name, it is text. I hope you know what text means. It means "words" or "sentences".

Run the file. Then, you can try the following if you are using Python 3.x:

>>> import hello
>>> hello.say("hi")
hi
>>> from hello import say
>>> say("test")
test

For Python 2.x - I guess same thing with Python 3? No idea. Correct me if I made a mistake on Python 2.x (I know Python 2 but I am used with Python 3)

Android: show/hide status bar/power bar

with this method, using SYSTEM_UI_FLAG_IMMERSIVE_STICKY the full screen come back with one tap without any implementation. Just copy past this method below and call it where you want in your activity. More details here

private void hideSystemUI() {
    getWindow().getDecorView().setSystemUiVisibility(
            View.SYSTEM_UI_FLAG_IMMERSIVE
                    // Set the content to appear under the system bars so that the
                    // content doesn't resize when the system bars hide and show.
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    // Hide the nav bar and status bar
                    | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_FULLSCREEN);
}

How to update Ruby with Homebrew?

I would use ruby-build with rbenv. The following lines install Ruby 3.0.0 and set it as your default Ruby version:

$ brew update
$ brew install ruby-build
$ brew install rbenv

$ rbenv install 3.0.0
$ rbenv global 3.0.0

jQuery multiple events to trigger the same function

You can use bind method to attach function to several events. Just pass the event names and the handler function as in this code:

$('#foo').bind('mouseenter mouseleave', function() {
  $(this).toggleClass('entered');
});

Another option is to use chaining support of jquery api.

How to print variable addresses in C?

When you intend to print the memory address of any variable or a pointer, using %d won't do the job and will cause some compilation errors, because you're trying to print out a number instead of an address, and even if it does work, you'd have an intent error, because a memory address is not a number. the value 0xbfc0d878 is surely not a number, but an address.

What you should use is %p. e.g.,

#include<stdio.h>

int main(void) {

    int a;
    a = 5;
    printf("The memory address of a is: %p\n", (void*) &a);
    return 0;
}

Good luck!

Add two numbers and display result in textbox with Javascript

Here a working fiddle: http://jsfiddle.net/sjh36otu/

        function add_number() {

            var first_number = parseInt(document.getElementById("Text1").value);
            var second_number = parseInt(document.getElementById("Text2").value);
            var result = first_number + second_number;

            document.getElementById("txtresult").value = result;
        }

Facebook development in localhost

The application will run just fine in localhost: 3000, you just need to specify the https address on which the application will be live when it be in production mode.
Option 2 is provide the url or you heroku website which lets you have sample application in production mode.

enter image description here

Set type for function parameters?

No, instead you would need to do something like this depending on your needs:

function myFunction(myDate, myString) {
  if(arguments.length > 1 && typeof(Date.parse(myDate)) == "number" && typeof(myString) == "string") {
    //Code here
  }
}

How to set selected index JComboBox by value

Just call comboBox.updateUI() after doing comboBox.setSelectedItem or comboBox.setSelectedIndex or comboModel.setSelectedItem

How does one use glide to download an image into a bitmap?

This is what worked for me: https://github.com/bumptech/glide/wiki/Custom-targets#overriding-default-behavior

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.transition.Transition;
import com.bumptech.glide.request.target.BitmapImageViewTarget;

...

Glide.with(yourFragment)
  .load("yourUrl")
  .asBitmap()
  .into(new BitmapImageViewTarget(yourImageView) {
    @Override
    public void onResourceReady(Bitmap bitmap, Transition<? super Bitmap> anim) {
        super.onResourceReady(bitmap, anim);
        Palette.generateAsync(bitmap, new Palette.PaletteAsyncListener() {  
            @Override
            public void onGenerated(Palette palette) {
                // Here's your generated palette
                Palette.Swatch swatch = palette.getDarkVibrantSwatch();
                int color = palette.getDarkVibrantColor(swatch.getTitleTextColor());
            }
        });
    }
});

Embed ruby within URL : Middleman Blog

<%= link_to "http://www.facebook.com/sharer.php?u=" + article_url(article, :text => article.title), :class => "btn btn-primary" do %>   <i class="fa fa-facebook">     Facebook Share    </i> <%end%> 

I am assuming that current_article_url is http://0.0.0.0:4567/link_to_title

How do I compare two Integers?

This is what the equals method does:

public boolean equals(Object obj) {
    if (obj instanceof Integer) {
        return value == ((Integer)obj).intValue();
    }
    return false;
}

As you can see, there's no hash code calculation, but there are a few other operations taking place there. Although x.intValue() == y.intValue() might be slightly faster, you're getting into micro-optimization territory there. Plus the compiler might optimize the equals() call anyway, though I don't know that for certain.

I generally would use the primitive int, but if I had to use Integer, I would stick with equals().

uint8_t vs unsigned char

The whole point is to write implementation-independent code. unsigned char is not guaranteed to be an 8-bit type. uint8_t is (if available).

Integrating the ZXing library directly into my Android application

If you just need the core.jar from zxing, you can skip that process and get the pre-built JARs from the GettingStarted wiki page

Latest ZXing (2.2) doesn't have core.jar under core folder but you can obtain the core.jar from the zxing Maven repository here

PHP multidimensional array search by value

I modified one of examples below description function array_search. Function searchItemsByKey return all value(s) by $key from multidimensional array ( N levels). Perhaps , it would be useful for somebody. Example:

 $arr = array(
     'XXX'=>array(
               'YYY'=> array(
                    'AAA'=> array(
                          'keyN' =>'value1'
                   )
               ),
              'ZZZ'=> array(
                    'BBB'=> array(
                          'keyN' => 'value2'
                   )
               )
              //.....
           )
);


$result = searchItemsByKey($arr,'keyN');

print '<pre>';
print_r($result);
print '<pre>';
// OUTPUT
Array
(
  [0] => value1
  [1] => value2
)

Function code:

function searchItemsByKey($array, $key)
{
   $results = array();

  if (is_array($array))
  {
    if (isset($array[$key]) && key($array)==$key)
        $results[] = $array[$key];

    foreach ($array as $sub_array)
        $results = array_merge($results, searchItemsByKey($sub_array, $key));
  }

 return  $results;
}

Git credential helper - update password

First find the version you are using with the Git command git --version. If you have a newer version than 1.7.10, then simply use this command:

git config --global credential.helper wincred

Then do the git fetch , then it prompts for the password update.

Now, it won't prompt for the password for multiple times in Git.

Where do I call the BatchNormalization function in Keras?

It's almost become a trend now to have a Conv2D followed by a ReLu followed by a BatchNormalization layer. So I made up a small function to call all of them at once. Makes the model definition look a whole lot cleaner and easier to read.

def Conv2DReluBatchNorm(n_filter, w_filter, h_filter, inputs):
    return BatchNormalization()(Activation(activation='relu')(Convolution2D(n_filter, w_filter, h_filter, border_mode='same')(inputs)))

Creating a file name as a timestamp in a batch job

This works well with (my) German locale, should be possible to adjust it to your needs...

forfiles /p *PATH* /m *filepattern* /c "cmd /c ren @file 
%DATE:~6,4%%DATE:~3,2%%DATE:~0,2%_@file"

Segmentation Fault - C

char *s  does not have some memory allocated . You need to allocate it manually in your case . You can do it as follows
s = (char *)malloc(100) ;

This would not lead to segmentation fault error as you will not be refering to an unknown location anymore

The model backing the 'ApplicationDbContext' context has changed since the database was created

Just Delete the migration History in _MigrationHistory in your DataBase. It worked for me

MavenError: Failed to execute goal on project: Could not resolve dependencies In Maven Multimodule project

In my case I forgot it was packaging conflict jar vs pom. I forgot to write

<packaging>pom</packaging>

In every child pom.xml file

Select subset of columns in data.table R

Another alternative is to use .SDcols

cols = paste0("V", c(1,2,3,5))
dt[, .SD, .SDcols=-cols]

RequiredIf Conditional Validation Attribute

The main difference from other solutions here is that this one reuses logic in RequiredAttribute on the server side, and uses required's validation method depends property on the client side:

public class RequiredIf : RequiredAttribute, IClientValidatable
{
    public string OtherProperty { get; private set; }
    public object OtherPropertyValue { get; private set; }

    public RequiredIf(string otherProperty, object otherPropertyValue)
    {
        OtherProperty = otherProperty;
        OtherPropertyValue = otherPropertyValue;
    }

    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        PropertyInfo otherPropertyInfo = validationContext.ObjectType.GetProperty(OtherProperty);
        if (otherPropertyInfo == null)
        {
            return new ValidationResult($"Unknown property {OtherProperty}");
        }

        object otherValue = otherPropertyInfo.GetValue(validationContext.ObjectInstance, null);
        if (Equals(OtherPropertyValue, otherValue)) // if other property has the configured value
            return base.IsValid(value, validationContext);

        return null;
    }

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule();
        rule.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName());
        rule.ValidationType = "requiredif"; // data-val-requiredif
        rule.ValidationParameters.Add("other", OtherProperty); // data-val-requiredif-other
        rule.ValidationParameters.Add("otherval", OtherPropertyValue); // data-val-requiredif-otherval

        yield return rule;
    }
}

$.validator.unobtrusive.adapters.add("requiredif", ["other", "otherval"], function (options) {
    var value = {
        depends: function () {
            var element = $(options.form).find(":input[name='" + options.params.other + "']")[0];
            return element && $(element).val() == options.params.otherval;
        }
    }
    options.rules["required"] = value;
    options.messages["required"] = options.message;
});

"Could not find Developer Disk Image"

This solution works only if you create in Xcode 7 the directory "10.0" and you have a mistake in your sentence:

ln -s /Applications/Xcode_8.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/10.0 \(14A345\) /Applications/Xcode_7.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/10.0

Android translate animation - permanently move View to new position using AnimationListener

Just Do like this

view.animate()
            .translationY(-((root.height - (view.height)) / 2).toFloat())
            .setInterpolator(AccelerateInterpolator()).duration = 1500

Here, view is your View which is animating from its origin position. root is root View of your XML file.

Calculation inside translationY is made for moving your view to the top but keeping it inside the screen, otherwise, it will go partially outside of the screen if you keep its value 0.

Quickest way to find missing number in an array of numbers

We can use XOR operation which is safer than summation because in programming languages if the given input is large it may overflow and may give wrong answer.

Before going to the solution, know that A xor A = 0. So if we XOR two identical numbers the value is 0.

Now, XORing [1..n] with the elements present in the array cancels the identical numbers. So at the end we will get the missing number.

// Assuming that the array contains 99 distinct integers between 1..99
// and empty slot value is zero
int XOR = 0;
for(int i=0; i<100; i++) {
    if (ARRAY[i] != 0) // remove this condition keeping the body if no zero slot
        XOR ^= ARRAY[i];
    XOR ^= (i + 1);
}
return XOR;
//return XOR ^ ARRAY.length + 1; if your array doesn't have empty zero slot. 

AngularJS : When to use service instead of factory

allernhwkim originally posted an answer on this question linking to his blog, however a moderator deleted it. It's the only post I've found which doesn't just tell you how to do the same thing with service, provider and factory, but also tells you what you can do with a provider that you can't with a factory, and with a factory that you can't with a service.

Directly from his blog:

app.service('CarService', function() {
   this.dealer="Bad";
    this.numCylinder = 4;
});

app.factory('CarFactory', function() {
    return function(numCylinder) {
      this.dealer="Bad";
        this.numCylinder = numCylinder
    };
});

app.provider('CarProvider', function() {
    this.dealerName = 'Bad';
    this.$get = function() {
        return function(numCylinder) {
            this.numCylinder = numCylinder;
            this.dealer = this.dealerName;
        }
    };
    this.setDealerName = function(str) {
      this.dealerName = str;
    }      
});

This shows how the CarService will always a produce a car with 4 cylinders, you can't change it for individual cars. Whereas CarFactory returns a function so you can do new CarFactory in your controller, passing in a number of cylinders specific to that car. You can't do new CarService because CarService is an object not a function.

The reason factories don't work like this:

app.factory('CarFactory', function(numCylinder) {
      this.dealer="Bad";
      this.numCylinder = numCylinder
});

And automatically return a function for you to instantiate, is because then you can't do this (add things to the prototype/etc):

app.factory('CarFactory', function() {
    function Car(numCylinder) {
        this.dealer="Bad";
        this.numCylinder = numCylinder
    };
    Car.prototype.breakCylinder = function() {
        this.numCylinder -= 1;
    };
    return Car;
});

See how it is literally a factory producing a car.

The conclusion from his blog is pretty good:

In conclusion,

---------------------------------------------------  
| Provider| Singleton| Instantiable | Configurable|
---------------------------------------------------  
| Factory | Yes      | Yes          | No          |
---------------------------------------------------  
| Service | Yes      | No           | No          |
---------------------------------------------------  
| Provider| Yes      | Yes          | Yes         |       
---------------------------------------------------  
  1. Use Service when you need just a simple object such as a Hash, for example {foo;1, bar:2} It’s easy to code, but you cannot instantiate it.

  2. Use Factory when you need to instantiate an object, i.e new Customer(), new Comment(), etc.

  3. Use Provider when you need to configure it. i.e. test url, QA url, production url.

If you find you're just returning an object in factory you should probably use service.

Don't do this:

app.factory('CarFactory', function() {
    return {
        numCylinder: 4
    };
});

Use service instead:

app.service('CarService', function() {
    this.numCylinder = 4;
});

Android Gradle Apache HttpClient does not exist?

The version of the Apache HTTP client provided on stock Android was very very old.

Google Android 1.0 was released with a pre-BETA snapshot of Apache HttpClient. To coincide with the first Android release Apache HttpClient 4.0 APIs had to be frozen prematurely, while many of interfaces and internal structures were still not fully worked out. As Apache HttpClient 4.0 was maturing the project was expecting Google to incorporate the latest code improvements into their code tree. Unfortunately it did not happen.

While you could keep using the old deprecated library via the useLibrary 'org.apache.http.legacy' workaround (suggested by @Jinu and others), you really need to bite the bullet and update to something else, for example the native Android HttpUrlConnection, or if that doesn't meet your needs, you can use the OkHttp library, which is what HttpUrlConnection is internally based upon anyway.

OkHttp actually has a compatibility layer that uses the same API as the Apache client, though they don't implement all of the same features, so your mileage may vary.

While it is possible to import a newer version of the Apache client (as suggested by @MartinPfeffer), it's likely that most of the classes and methods you were using before have been deprecated, and there is a pretty big risk that updating will introduce bugs in your code (for example I found some connections that previously worked from behind a proxy no longer worked), so this isn't a great solution.

How to zip a file using cmd line?

Not exactly zipping, but you can compact files in Windows with the compact command:

compact /c /s:<directory or file>

And to uncompress:

compact /u /s:<directory or file>

NOTE: These commands only mark/unmark files or directories as compressed in the file system. They do not produces any kind of archive (like zip, 7zip, rar, etc.)

How do I get the name of the rows from the index of a data frame?

if you want to get the index values, you can simply do:

dataframe.index

this will output a pandas.core.index

Python: How to use RegEx in an if statement?

if re.match(regex, content):
  blah..

You could also use re.search depending on how you want it to match.

How do I pass the this context to a function?

You can use the bind function to set the context of this within a function.

function myFunc() {
  console.log(this.str)
}
const myContext = {str: "my context"}
const boundFunc = myFunc.bind(myContext);
boundFunc(); // "my context"

Determining the current foreground application from a background task or service

Taking into account that getRunningTasks() is deprecated and getRunningAppProcesses() is not reliable, I came to decision to combine 2 approaches mentioned in StackOverflow:

   private boolean isAppInForeground(Context context)
    {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP)
        {
            ActivityManager am = (ActivityManager) context.getSystemService(ACTIVITY_SERVICE);
            ActivityManager.RunningTaskInfo foregroundTaskInfo = am.getRunningTasks(1).get(0);
            String foregroundTaskPackageName = foregroundTaskInfo.topActivity.getPackageName();

            return foregroundTaskPackageName.toLowerCase().equals(context.getPackageName().toLowerCase());
        }
        else
        {
            ActivityManager.RunningAppProcessInfo appProcessInfo = new ActivityManager.RunningAppProcessInfo();
            ActivityManager.getMyMemoryState(appProcessInfo);
            if (appProcessInfo.importance == IMPORTANCE_FOREGROUND || appProcessInfo.importance == IMPORTANCE_VISIBLE)
            {
                return true;
            }

            KeyguardManager km = (KeyguardManager) context.getSystemService(Context.KEYGUARD_SERVICE);
            // App is foreground, but screen is locked, so show notification
            return km.inKeyguardRestrictedInputMode();
        }
    }

Django optional url parameters

Even simpler is to use:

(?P<project_id>\w+|)

The "(a|b)" means a or b, so in your case it would be one or more word characters (\w+) or nothing.

So it would look like:

url(
    r'^project_config/(?P<product>\w+)/(?P<project_id>\w+|)/$',
    'tool.views.ProjectConfig',
    name='project_config'
),

How to merge two json string in Python?

You can load both json strings into Python Dictionaries and then combine. This will only work if there are unique keys in each json string.

import json

a = json.loads(jsonStringA)
b = json.loads(jsonStringB)
c = dict(a.items() + b.items())
# or c =  dict(a, **b)

How do I escape ampersands in batch files?

If you need to echo a string that contains an ampersand, quotes won't help, because you would see them on the output as well. In such a case, use for:

for %a in ("First & Last") do echo %~a

...in a batch script:

for %%a in ("First & Last") do echo %%~a

or

for %%a in ("%~1") do echo %%~a

Converting a Date object to a calendar object

Here's your method:

public static Calendar toCalendar(Date date){ 
  Calendar cal = Calendar.getInstance();
  cal.setTime(date);
  return cal;
}

Everything else you are doing is both wrong and unnecessary.

BTW, Java Naming conventions suggest that method names start with a lower case letter, so it should be: dateToCalendar or toCalendar (as shown).


OK, let's milk your code, shall we?

DateFormat formatter = new SimpleDateFormat("yyyyMMdd");
date = (Date)formatter.parse(date.toString()); 

DateFormat is used to convert Strings to Dates (parse()) or Dates to Strings (format()). You are using it to parse the String representation of a Date back to a Date. This can't be right, can it?

how to open *.sdf files?

It can be opened using Visual Studio 2012.Follow the below path in VS after opening the project. View->Server Explorer->

enter image description here

Font size of TextView in Android application changes on changing font size from native settings

Use the dimension type of resources like you use string resources (DOCS).

In your dimens.xml file, declare your dimension variables:

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <dimen name="textview_height">25dp</dimen>
  <dimen name="textview_width">150dp</dimen>
  <dimen name="ball_radius">30dp</dimen>
  <dimen name="font_size">16sp</dimen>
</resources>

Then you can use these values like this:

<TextView
   android:layout_height="@dimen/textview_height"
   android:layout_width="@dimen/textview_width"
   android:textSize="@dimen/font_size"/>

You can declare different dimens.xml files for different types of screens. Doing this will guarantee the desired look of your app on different devices.

When you don't specify android:textSize the system uses the default values.

Android: How to Enable/Disable Wifi or Internet Connection Programmatically

To Enable WiFi:

WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
wifi.setWifiEnabled(true);

To Disable WiFi:

WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
wifi.setWifiEnabled(false);

Note: To access with WiFi state, we have to add following permissions inside the AndroidManifest.xml file:

android.permission.ACCESS_WIFI_STATE
android.permission.UPDATE_DEVICE_STATS 
android.permission.CHANGE_WIFI_STATE

Using an Alias in a WHERE clause

 SELECT A.identifier
 , A.name
 , TO_NUMBER(DECODE( A.month_no
         , 1, 200803 
         , 2, 200804 
         , 3, 200805 
         , 4, 200806 
         , 5, 200807 
         , 6, 200808 
         , 7, 200809 
         , 8, 200810 
         , 9, 200811 
         , 10, 200812 
         , 11, 200701 
         , 12, 200702
         , NULL)) as MONTH_NO
 , TO_NUMBER(TO_CHAR(B.last_update_date, 'YYYYMM')) as UPD_DATE
FROM table_a A, table_b B
WHERE .identifier = B.identifier
HAVING MONTH_NO > UPD_DATE

CASE IN statement with multiple values

The question is specific to SQL Server, but I would like to extend Martin Smith's answer.

SQL:2003 standard allows to define multiple values for simple case expression:

SELECT CASE c.Number
          WHEN '1121231','31242323' THEN 1
          WHEN '234523','2342423' THEN 2
       END AS Test
FROM tblClient c;

It is optional feature: Comma-separated predicates in simple CASE expression“ (F263).

Syntax:

CASE <common operand>
     WHEN <expression>[, <expression> ...] THEN <result>
    [WHEN <expression>[, <expression> ...] THEN <result>
     ...]
    [ELSE <result>]
END

As for know I am not aware of any RDBMS that actually supports that syntax.

What's the difference between a temp table and table variable in SQL Server?

The other main difference is that table variables don't have column statistics, where as temp tables do. This means that the query optimiser doesn't know how many rows are in the table variable (it guesses 1), which can lead to highly non-optimal plans been generated if the table variable actually has a large number of rows.

Best way to check if a URL is valid

You can use this function, but its will return false if website offline.

  function isValidUrl($url) {
    $url = parse_url($url);
    if (!isset($url["host"])) return false;
    return !(gethostbyname($url["host"]) == $url["host"]);
}

Get value of input field inside an iframe

Without Iframe We can do this by JQuery but it will give you only HTML page source and no dynamic links or html tags will display. Almost same as php solution but in JQuery :) Code---

var purl = "http://www.othersite.com";
$.getJSON('http://whateverorigin.org/get?url=' +
    encodeURIComponent(purl) + '&callback=?',
    function (data) {
    $('#viewer').html(data.contents);
});

How do I run a Python program in the Command Prompt in Windows 7?

Python comes with a script that takes care of setting up the windows path file for you.

After installation, open command prompt

cmd

Go to the directory you installed Python in

cd C:\Python27

Run python and the win_add2path.py script in Tools\Scripts

python.exe Tools\Scripts\win_add2path.py

Now you can use python as a command anywhere.

Can I add and remove elements of enumeration at runtime in Java

You can load a Java class from source at runtime. (Using JCI, BeanShell or JavaCompiler)

This would allow you to change the Enum values as you wish.

Note: this wouldn't change any classes which referred to these enums so this might not be very useful in reality.

Html table with button on each row

Pretty sure this solves what you're looking for:

HTML:

<table>
    <tr><td><button class="editbtn">edit</button></td></tr>
    <tr><td><button class="editbtn">edit</button></td></tr>
    <tr><td><button class="editbtn">edit</button></td></tr>
    <tr><td><button class="editbtn">edit</button></td></tr>
</table>

Javascript (using jQuery):

$(document).ready(function(){
    $('.editbtn').click(function(){
        $(this).html($(this).html() == 'edit' ? 'modify' : 'edit');
    });
});

Edit:

Apparently I should have looked at your sample code first ;)

You need to change (at least) the ID attribute of each element. The ID is the unique identifier for each element on the page, meaning that if you have multiple items with the same ID, you'll get conflicts.

By using classes, you can apply the same logic to multiple elements without any conflicts.

JSFiddle sample

JNZ & CMP Assembly Instructions

JNZ     Jump if Not Zero    ZF=0

Indeed, this is confusing right.

To make it easier to understand, replace Not Zero with Not Set. (Please take note this is for your own understanding)

Hence,

JNZ     Jump if Not Set     ZF=0

Not Set means flag Z = 0. So Jump (Jump if Not Set)

Set means flag Z = 1. So, do NOT Jump

this in equals method

this refers to the current instance of the class (object) your equals-method belongs to. When you test this against an object, the testing method (which is equals(Object obj) in your case) will check wether or not the object is equal to the current instance (referred to as this).

An example:

Object obj = this; this.equals(obj); //true   Object obj = this; new Object().equals(obj); //false 

PostgreSQL: insert from another table

You could use coalesce:

insert into destination select coalesce(field1,'somedata'),... from source;

How to delete duplicate lines in a file without sorting it in Unix?

awk '!seen[$0]++' file.txt

seen is an associative-array that Awk will pass every line of the file to. If a line isn't in the array then seen[$0] will evaluate to false. The ! is the logical NOT operator and will invert the false to true. Awk will print the lines where the expression evaluates to true. The ++ increments seen so that seen[$0] == 1 after the first time a line is found and then seen[$0] == 2, and so on.
Awk evaluates everything but 0 and "" (empty string) to true. If a duplicate line is placed in seen then !seen[$0] will evaluate to false and the line will not be written to the output.

How to make link not change color after visited?

For application on all the anchor tags, use

CSS

a:visited{
    color:blue;
}

For application on only some of the anchor tags, use

CSS

.linkcolor a:visited{
    color:blue;
}

HTML

<span class="linkcolor"><a href="http://stackoverflow.com/" target="_blank">Go to Home</a></span>

Use multiple custom fonts using @font-face?

You simply add another @font-face rule:

@font-face {
    font-family: CustomFont;
    src: url('CustomFont.ttf');
}

@font-face {
    font-family: CustomFont2;
    src: url('CustomFont2.ttf');
}

If your second font still doesn't work, make sure you're spelling its typeface name and its file name correctly, your browser caches are behaving, your OS isn't messing around with a font of the same name, etc.

What's your most controversial programming opinion?

If you only know one language, no matter how well you know it, you're not a great programmer.

There seems to be an attitude that says once you're really good at C# or Java or whatever other language you started out learning then that's all you need. I don't believe it- every language I have ever learned has taught me something new about programming that I have been able to bring back into my work with all the others. I think that anyone who restricts themselves to one language will never be as good as they could be.

It also indicates to me a certain lack of inquistiveness and willingness to experiment that doesn't necessarily tally with the qualities I would expect to find in a really good programmer.

Returning pointer from a function

Allocate memory before using the pointer. If you don't allocate memory *point = 12 is undefined behavior.

int *fun()
{
    int *point = malloc(sizeof *point); /* Mandatory. */
    *point=12;  
    return point;
}

Also your printf is wrong. You need to dereference (*) the pointer.

printf("%d", *ptr);
             ^

Using sed to split a string with a delimiter

To split a string with a delimiter with GNU sed you say:

sed 's/delimiter/\n/g'     # GNU sed

For example, to split using : as a delimiter:

$ sed 's/:/\n/g' <<< "he:llo:you"
he
llo
you

Or with a non-GNU sed:

$ sed $'s/:/\\\n/g' <<< "he:llo:you"
he
llo
you

In this particular case, you missed the g after the substitution. Hence, it is just done once. See:

$ echo "string1:string2:string3:string4:string5" | sed s/:/\\n/g
string1
string2
string3
string4
string5

g stands for global and means that the substitution has to be done globally, that is, for any occurrence. See that the default is 1 and if you put for example 2, it is done 2 times, etc.

All together, in your case you would need to use:

sed 's/:/\\n/g' ~/Desktop/myfile.txt

Note that you can directly use the sed ... file syntax, instead of unnecessary piping: cat file | sed.

What is the usefulness of PUT and DELETE HTTP request methods?

Using HTTP Request verb such as GET, POST, DELETE, PUT etc... enables you to build RESTful web applications. Read about it here: http://en.wikipedia.org/wiki/Representational_state_transfer

The easiest way to see benefits from this is to look at this example. Every MVC framework has a Router/Dispatcher that maps URL-s to actionControllers. So URL like this: /blog/article/1 would invoke blogController::articleAction($id); Now this Router is only aware of the URL or /blog/article/1/

But if that Router would be aware of whole HTTP Request object instead of just URL, he could have access HTTP Request verb (GET, POST, PUT, DELETE...), and many other useful stuff about current HTTP Request.

That would enable you to configure application so it can accept the same URL and map it to different actionControllers depending on the HTTP Request verb.

For example:

if you want to retrive article 1 you can do this:

GET /blog/article/1 HTTP/1.1

but if you want to delete article 1 you will do this:

DELETE /blog/article/1 HTTP/1.1

Notice that both HTTP Requests have the same URI, /blog/article/1, the only difference is the HTTP Request verb. And based on that verb your router can call different actionController. This enables you to build neat URL-s.

Read this two articles, they might help you:

Symfony 2 - HTTP Fundamentals

Symfony 2 - Routing

These articles are about Symfony 2 framework, but they can help you to figure out how does HTTP Requests and Responses work.

Hope this helps!

How to filter Pandas dataframe using 'in' and 'not in' like in SQL

You can use pd.Series.isin.

For "IN" use: something.isin(somewhere)

Or for "NOT IN": ~something.isin(somewhere)

As a worked example:

import pandas as pd

>>> df
  country
0        US
1        UK
2   Germany
3     China
>>> countries_to_keep
['UK', 'China']
>>> df.country.isin(countries_to_keep)
0    False
1     True
2    False
3     True
Name: country, dtype: bool
>>> df[df.country.isin(countries_to_keep)]
  country
1        UK
3     China
>>> df[~df.country.isin(countries_to_keep)]
  country
0        US
2   Germany

How to include External CSS and JS file in Laravel 5

I may be late to the party but it's easy to include JS and CSS the Laravel Way by simply using asset() function

e.g. <link rel="stylesheet" href="{{ asset('css/app.css') }}" />

Hope that helps

grep a file, but show several surrounding lines?

-A and -B will work, as will -C n (for n lines of context), or just -n (for n lines of context... as long as n is 1 to 9).

curl_init() function not working

For Ubuntu: add extension=php_curl.so to php.ini to enable, if necessary. Then sudo service apache2 restart

this is generally taken care of automatically, but there are situations - eg, in shared development environments - where it can become necessary to re-enable manually.

The thumbprint will match all three of these conditions:

  1. Fatal Error on curl_init() call
  2. in php_info, you will see the curl module author (indicating curl is installed and available)
  3. also in php_info, you will see no curl config block (indicating curl wasn't loaded)

How to extract svg as file from web page

Based on a web search, I just found a Chrome plugin called SVG Export.

What's the reason I can't create generic array types in Java?

It is because generics were added on to java after they made it, so its kinda clunky because the original makers of java thought that when making an array the type would be specified in the making of it. So that does not work with generics so you have to do E[] array=(E[]) new Object[15]; This compiles but it gives a warning.

Difference between onLoad and ng-init in angular

From angular's documentation,

ng-init SHOULD NOT be used for any initialization. It should be used only for aliasing. https://docs.angularjs.org/api/ng/directive/ngInit

onload should be used if any expression needs to be evaluated after a partial view is loaded (by ng-include). https://docs.angularjs.org/api/ng/directive/ngInclude

The major difference between them is when used with ng-include.

<div ng-include="partialViewUrl" onload="myFunction()"></div>

In this case, myFunction is called everytime the partial view is loaded.

<div ng-include="partialViewUrl" ng-init="myFunction()"></div>

Whereas, in this case, myFunction is called only once when the parent view is loaded.

Why do symbols like apostrophes and hyphens get replaced with black diamonds on my website?

I experienced the same problem when I copied a text that has an apostrophe from a Word document to my HTML code.

To resolve the issue, all I did was deleted the particular word in my HTML and typed it directly, including the apostrophe. This action nullified the original copy and paste acton and displayed the newly typed apostrophe correctly

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

The best way to go about this is to use 'BatchMode' in addition to 'StrictHostKeyChecking'. This way, your script will accept a new hostname and write it to the known_hosts file, but won't require yes/no intervention.

ssh -o BatchMode=yes -o StrictHostKeyChecking=no [email protected] "uptime"

How to override equals method in Java

Introducing a new method signature that changes the parameter types is called overloading:

public boolean equals(People other){

Here People is different than Object.

When a method signature remains the identical to that of its superclass, it is called overriding and the @Override annotation helps distinguish the two at compile-time:

@Override
public boolean equals(Object other){

Without seeing the actual declaration of age, it is difficult to say why the error appears.

AngularJS/javascript converting a date String to date object

try this

html

<div ng-controller="MyCtrl">
  Hello, {{newDate | date:'MM/dd/yyyy'}}!
</div>

JS

var myApp = angular.module('myApp',[]);

function MyCtrl($scope) {
    var collectionDate = '2002-04-26T09:00:00'; 

    $scope.newDate =new Date(collectionDate);
}

Demo

SQL select max(date) and corresponding value

There's no easy way to do this, but something like this will work:

SELECT ET.TrainingID, 
  ET.CompletedDate, 
  ET.Notes
FROM 
HR_EmployeeTrainings ET
inner join
(
  select TrainingID, Max(CompletedDate) as CompletedDate
  FROM HR_EmployeeTrainings
  WHERE (ET.AvantiRecID IS NULL OR ET.AvantiRecID = @avantiRecID)
  GROUP BY AvantiRecID, TrainingID  
) ET2 
  on ET.TrainingID = ET2.TrainingID
  and ET.CompletedDate = ET2.CompletedDate

Portable way to check if directory exists [Windows/Linux, C]

You can use the GTK glib to abstract from OS stuff.

glib provides a g_dir_open() function which should do the trick.

CSS3 Transparency + Gradient

This is some really cool stuff! I needed pretty much the same, but with horizontal gradient from white to transparent. And it is working just fine! Here ist my code:

.gradient{
        /* webkit example */
        background-image: -webkit-gradient(
          linear, right top, left top, from(rgba(255, 255, 255, 1.0)),
          to(rgba(255, 255, 255, 0))
        );

        /* mozilla example - FF3.6+ */
        background-image: -moz-linear-gradient(
          right center,
          rgba(255, 255, 255, 1.0) 20%, rgba(255, 255, 255, 0) 95%
        );

        /* IE 5.5 - 7 */
        filter: progid:DXImageTransform.Microsoft.gradient(
          gradientType=1, startColor=0, endColorStr=#FFFFFF
        );

        /* IE8 uses -ms-filter for whatever reason... */
        -ms-filter: progid:DXImageTransform.Microsoft.gradient(
          gradientType=1, startColor=0, endColoStr=#FFFFFF
        );
    }

Troubleshooting BadImageFormatException

When I faced this issue the following solved it for me:

I was calling a OpenCV dll from inside another exe, my dll did not contained the already needed opencv dlls like highgui, features2d, and etc available in the folder of my exe file. I copied all these to the directory of my exe project and it suddenly worked.

Android Color Picker

try this open source projects that might help you

https://github.com/QuadFlask/colorpicker

Use formula in custom calculated field in Pivot Table

Some of it is possible, specifically accessing subtotals:

"In Excel 2010+, you can right-click on the values and select Show Values As –> % of Parent Row Total." (or % of Parent Column Total)

enter image description here

  • And make sure the field in question is a number field that can be summed, it does not work for text fields for which only count is normally informative.

Source: http://datapigtechnologies.com/blog/index.php/excel-2010-pivottable-subtotals/

What's a decent SFTP command-line client for windows?

This little application does the job for me. I could not find another CLI based client that would access my IIS based TLS/SSL secured ftp site: http://netwinsite.com/surgeftp/sslftp.htm

HTTP Status 405 - Request method 'POST' not supported (Spring MVC)

You might need to change the line

@RequestMapping(value = "/add", method = RequestMethod.GET)

to

@RequestMapping(value = "/add", method = {RequestMethod.GET,RequestMethod.POST})

How can I create a self-signed cert for localhost?

you could try mkcert.

macos: brew install mkcert

How to format a float in javascript?

var result = Math.round(original*100)/100;

The specifics, in case the code isn't self-explanatory.

edit: ...or just use toFixed, as proposed by Tim Büthe. Forgot that one, thanks (and an upvote) for reminder :)

PHP fopen() Error: failed to open stream: Permission denied

You may need to change the permissions as an administrator. Open up terminal on your Mac and then open the directory that markers.xml is located in. Then type:

sudo chmod 777 markers.xml

You may be prompted for a password. Also, it could be the directories that don't allow full access. I'm not familiar with WordPress, so you may have to change the permission of each directory moving upward to the mysite directory.

Python nonlocal statement

My personal understanding of the "nonlocal" statement (and do excuse me as I am new to Python and Programming in general) is that the "nonlocal" is a way to use the Global functionality within iterated functions rather than the body of the code itself. A Global statement between functions if you will.

How to margin the body of the page (html)?

Html for content, CSS for style

<body style='margin-top:0;margin-left:0;margin-right:0;'>

How to use Python to execute a cURL command?

Just use this website. It'll convert any curl command into Python, Node.js, PHP, R, or Go.

Example:

curl -X POST -H 'Content-type: application/json' --data '{"text":"Hello, World!"}' https://hooks.slack.com/services/asdfasdfasdf

Becomes this in Python,

import requests

headers = {
    'Content-type': 'application/json',
}

data = '{"text":"Hello, World!"}'

response = requests.post('https://hooks.slack.com/services/asdfasdfasdf', headers=headers, data=data)

Assert an object is a specific type

You can use the assertThat method and the Matchers that comes with JUnit.

Take a look at this link that describes a little bit about the JUnit Matchers.

Example:

public class BaseClass {
}

public class SubClass extends BaseClass {
}

Test:

import org.junit.Test;

import static org.hamcrest.CoreMatchers.instanceOf;
import static org.junit.Assert.assertThat;

/**
 * @author maba, 2012-09-13
 */
public class InstanceOfTest {

    @Test
    public void testInstanceOf() {
        SubClass subClass = new SubClass();
        assertThat(subClass, instanceOf(BaseClass.class));
    }
}

Using grep to search for a string that has a dot in it

You can also use "[.]"

grep -r "0[.]49"

AWS CLI S3 A client error (403) occurred when calling the HeadObject operation: Forbidden

I was getting this error message due to my EC2 instance's clock being out of sync.

I was able to fix on Ubuntu using this:

sudo ntpdate ntp.ubuntu.com
sudo apt-get install ntp

How can I read a text file in Android?

Shortest form for small text files (in Kotlin):

val reader = FileReader(path)
val txt = reader.readText()
reader.close()

How do I concatenate or merge arrays in Swift?

Swift 5 Array Extension

extension Array where Element: Sequence {
    func join() -> Array<Element.Element> {
        return self.reduce([], +)
    }
}

Example:

let array = [[1,2,3], [4,5,6], [7,8,9]]
print(array.join())

//result: [1, 2, 3, 4, 5, 6, 7, 8, 9]

Java - Relative path of a file in a java web application

You may be able to simply access a pre-arranged file path on the system. This is preferable since files added to the webapp directory might be lost or the webapp may not be unpacked depending on system configuration.

In our server, we define a system property set in the App Server's JVM which points to the "home directory" for our app's external data. Of course this requires modification of the App Server's configuration (-DAPP_HOME=... added to JVM_OPTS at startup), we do it mainly to ease testing of code run outside the context of an App Server.

You could just as easily retrieve a path from the servlet config:

<web-app>
<context-param>
    <param-name>MyAppHome</param-name>
    <param-value>/usr/share/myapp</param-value>
</context-param>
...
</web-app>

Then retrieve this path and use it as the base path to read the file supplied by the client.

public class MyAppConfig implements ServletContextListener {

    // NOTE: static references are not a great idea, shown here for simplicity
    static File appHome;
    static File customerDataFile;

    public void contextInitialized(ServletContextEvent e) {

        appHome = new File(e.getServletContext().getInitParameter("MyAppHome"));
        File customerDataFile = new File(appHome, "SuppliedFile.csv");
    }
}

class DataProcessor {
    public void processData() {
        File dataFile = MyAppConfig.customerDataFile;
        // ...
    }
}

As I mentioned the most likely problem you'll encounter is security restrictions. Nothing guarantees webapps can ready any files above their webapp root. But there are generally simple methods for granting exceptions for specific paths to specific webapps.

Regardless of the code in which you then need to access this file, since you are running within a web application you are guaranteed this is initialized first, and can stash it's value somewhere convenient for the rest of your code to refer to, as in my example or better yet, just simply pass the path as a paramete to the code which needs it.

Why do I get java.lang.AbstractMethodError when trying to load a blob in the db?

Here's what the JDK API says about AbstractMethodError:

Thrown when an application tries to call an abstract method. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of some class has incompatibly changed since the currently executing method was last compiled.

Bug in the oracle driver, maybe?

What are the differences between JSON and JSONP?

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

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

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

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

Difference between x86, x32, and x64 architectures?

Hans and DarkDust answer covered i386/i686 and amd64/x86_64, so there's no sense in revisiting them. This answer will focus on X32, and provide some info learned after a X32 port.

x32 is an ABI for amd64/x86_64 CPUs using 32-bit integers, longs and pointers. The idea is to combine the smaller memory and cache footprint from 32-bit data types with the larger register set of x86_64. (Reference: Debian X32 Port page).

x32 can provide up to about 30% reduction in memory usage and up to about 40% increase in speed. The use cases for the architecture are:

  • vserver hosting (memory bound)
  • netbooks/tablets (low memory, performance)
  • scientific tasks (performance)

x32 is a somewhat recent addition. It requires kernel support (3.4 and above), distro support (see below), libc support (2.11 or above), and GCC 4.8 and above (improved address size prefix support).

For distros, it was made available in Ubuntu 13.04 or Fedora 17. Kernel support only required pointer to be in the range from 0x00000000 to 0xffffffff. From the System V Application Binary Interface, AMD64 (With LP64 and ILP32 Programming Models), Section 10.4, p. 132 (its the only sentence):

10.4 Kernel Support
Kernel should limit stack and addresses returned from system calls between 0x00000000 to 0xffffffff.

When booting a kernel with the support, you must use syscall.x32=y option. When building a kernel, you must include the CONFIG_X86_X32=y option. (Reference: Debian X32 Port page and X32 System V Application Binary Interface).


Here is some of what I have learned through a recent port after the Debian folks reported a few bugs on us after testing:

  • the system is a lot like X86
  • the preprocessor defines __x86_64__ (and friends) and __ILP32__, but not __i386__/__i686__ (and friends)
  • you cannot use __ILP32__ alone because it shows up unexpectedly under Clang and Sun Studio
  • when interacting with the stack, you must use the 64-bit instructions pushq and popq
  • once a register is populated/configured from 32-bit data types, you can perform the 64-bit operations on them, like adcq
  • be careful of the 0-extension that occurs on the upper 32-bits.

If you are looking for a test platform, then you can use Debian 8 or above. Their wiki page at Debian X32 Port has all the information. The 3-second tour: (1) enable X32 in the kernel at boot; (2) use debootstrap to install the X32 chroot environment, and (3) chroot debian-x32 to enter into the environment and test your software.

How to connect to SQL Server from command prompt with Windows authentication

After some tries, these are the samples I am using in order to connect:

Specifying the username and the password:

sqlcmd -S 211.11.111.111 -U NotSA -P NotTheSaPassword

Specifying the DB as well:

sqlcmd -S 211.11.111.111 -d SomeSpecificDatabase -U NotSA -P NotTheSaPassword

Mongoose, Select a specific field with find

Exclude

Below code will retrieve all fields other than password within each document:

const users = await UserModel.find({}, {
  password: 0 
});
console.log(users);

Output

[
  {
    "_id": "5dd3fb12b40da214026e0658",
    "email": "[email protected]"
  }
]

Include

Below code will only retrieve email field within each document:

const users = await UserModel.find({}, {
  email: 1
});
console.log(users);

Output

[
  {
    "email": "[email protected]"
  }
]

In Python, how do I determine if an object is iterable?

Since Python 3.5 you can use the typing module from the standard library for type related things:

from typing import Iterable

...

if isinstance(my_item, Iterable):
    print(True)