 |  |
1.2. Accessing Substrings
You want to extract part of a string, starting at a particular place in the string. For example, you want the first eight characters of a username entered into a form.
1.2.1. Solution
Use substr( ) to select your substrings:
$substring = substr($string,$start,$length); $username = substr($_REQUEST['username'],0,8);
1.2.2. Discussion
If $start and $length are positive, substr( ) returns $length characters in the string, starting at $start. The first character in the string is at position 0:
print substr('watch out for that tree',6,5);
out fIf you leave out $length, substr( ) returns the string from $start to the end of the original string:
print substr('watch out for that tree',17);
t treeIf $start plus $length goes past the end of the string, substr( ) returns all of the string from $start forward:
print substr('watch out for that tree',20,5);
reeIf $start is negative, substr( ) counts back from the end of the string to determine where your substring starts:
print substr('watch out for that tree',-6);
print substr('watch out for that tree',-17,5);
t tree
out fIf $length is negative, substr( ) counts back from the end of the string to determine where your substring ends:
print substr('watch out for that tree',15,-2);
print substr('watch out for that tree',-4,-1);
hat tr
tre1.2.3. See Also
Documentation on substr( ) at http://www.php.net/substr.
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| 1. Strings |  | 1.3. Replacing Substrings |
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