How to Check If a String "Startswith" Another String

How to check if a string StartsWith another string?

You can use ECMAScript 6's String.prototype.startsWith() method. It's supported in all major browsers. However, if you want to use it in a browser that is unsupported you'll want to use a shim/polyfill to add it on those browsers. Creating an implementation that complies with all the details laid out in the spec is a little complicated. If you want a faithful shim, use either:

Matthias Bynens's String.prototype.startsWith shim, or
The es6-shim, which shims as much of the ES6 spec as possible, including String.prototype.startsWith.

Once you've shimmed the method (or if you're only supporting browsers and JavaScript engines that already have it), you can use it like this:

console.log("Hello World!".startsWith("He")); // true

var haystack = "Hello world";
var prefix = 'orl';
console.log(haystack.startsWith(prefix)); // false

How to check if a string starts with another string in C?

Apparently there's no standard C function for this. So:

bool startsWith(const char *pre, const char *str)
{
    size_t lenpre = strlen(pre),
           lenstr = strlen(str);
    return lenstr < lenpre ? false : memcmp(pre, str, lenpre) == 0;
}

Note that the above is nice and clear, but if you're doing it in a tight loop or working with very large strings, it does not offer the best performance, as it scans the full length of both strings up front (strlen). Solutions like wj32's or Christoph's may offer better performance (although this comment about vectorization is beyond my ken of C). Also note Fred Foo's solution which avoids strlen on str (he's right, it's unnecessary if you use strncmp instead of memcmp). Only matters for (very) large strings or repeated use in tight loops, but when it matters, it matters.

Check if a String startsWith() and isn't equal to another String

you can use a regular expression to test for "starts with" in any version of javascript.

var value = 'Hello There';

if (/^Hello/.test(value) && value !== 'Hello World') {
  console.log('yes it is!')
}

How to check if a string starts with another string - PHP

Using strpos function can be achieved.

if (strpos($yourString, "repair") === 0) {
    //Starts with it
}

Using substr can work too:

if (substr($yourstring, 0, strlen($startString)) === $startString) {
    //It starts with desired string
}

For multi-byte strings, consider using functions with mb_ prefix, so mb_substr, mb_strlen, etc.

Check if a string startswith any element in a tuple, if True, return that element

This function takes a function of one argument and a list of arguments, and will return the first argument that makes the function return a truthy value. Otherwise, it will raise an error:

def first_matching(matches, candidates):
    try:
        return next(filter(matches, candidates))
    except StopIteration:
        raise ValueError("No matching candidate")

result = first_matching(user_input.startswith, commands)

Check if a string starts with another known string?

http://ideone.com/w1ifiJ

#include <iostream>
using namespace std;

int main() {
    string str ("abcdefghijklmnoabcde");
    string str2 ("abcde");

    size_t found = str.find(str2);

    if(found == 0)
    {
         cout << "found";
    }

    return 0;
  }

more info : http://www.cplusplus.com/reference/string/string/find/