if string begins with "xx" (PHP)

Question

if ($_POST['id'] beginsWith "gm") {
$_SESSION['game']=="gmod"
}
if ($_POST['id'] beginsWith "tf2") {
$_SESSION['game']=="tf2"
}

How to do this so it will work?

you have to write a patch in C code that adds this keyword/syntax — Gordon, Apr 29 '11 at 16:52

score 34 · Answer 1 · edited Jan 27 '12 at 02:56

34

You could use substring

if(substr($POST['id'],0,3) == 'tf2')
 {
  //Do something
 }

Edit: fixed incorrect function name (substring() used, should be substr())

edited Jan 27 '12 at 02:56

Zak Henry

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answered Apr 29 '11 at 16:52

Matt

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3

+1. this should be (marginally) faster than strpos since it won't traverse the entire string on failure. – Emil Vikström Apr 29 '11 at 16:54
@EmilVikström I **seriously** doubt your statement about `substr()` being faster than `strpos()`. In fact I believe it will be *slower*! – PeeHaa Aug 09 '12 at 08:44

score 24 · Answer 2 · answered Apr 29 '11 at 16:52

24

You can write a begins_with using strpos:

function begins_with($haystack, $needle) {
    return strpos($haystack, $needle) === 0;
}


if (begins_with($_POST['id'], "gm")) {
    $_SESSION['game']=="gmod"
}

// etc

answered Apr 29 '11 at 16:52

Jon

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gen_Eric · Accepted Answer · 2011-04-29T17:12:57.367

4

if (strpos($_POST['id'], "gm") === 0) {
  $_SESSION['game'] ="gmod"
}
if (strpos($_POST['id'],"tf2") === 0) {
  $_SESSION['game'] ="tf2"
}

edited Apr 29 '11 at 17:12

answered Apr 29 '11 at 16:54

gen_Eric

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1

This is wrong. If strpos returns false, both of those if statements will evaluate to true. – andrewtweber Apr 29 '11 at 17:01
@andrewtweber: There. Replaced the `==` with `===` :-P – gen_Eric Apr 29 '11 at 17:13

score 3 · Answer 4 · answered Apr 29 '11 at 17:55

3

NOT the fastest way to do it but you can use regex

if (preg_match("/^gm/", $_POST['id'])) {
    $_SESSION['game']=="gmod"
}
if (preg_match("/^tf2/, $_POST['id'])) {
    $_SESSION['game']=="tf2"
}

answered Apr 29 '11 at 17:55

Toto

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score 2 · Answer 5 · answered Apr 29 '11 at 16:54

function startswith($haystack, $needle){ 
    return strpos($haystack, $needle) === 0;
}

if (startswith($_POST['id'], 'gm')) {
    $_SESSION['game'] = 'gmod';
}
if (startswith($_POST['id'], 'tf2')) {
    $_SESSION['game'] = 'tf2';
}

Note that when assigning values to variable use a single =

if string begins with "xx" (PHP)

5 Answers5