Home > Article > Backend Development > PHP function strpos() to find the first occurrence of a string in another string (case sensitive)
Example
Find the first occurrence of "php" in the string:
<?php
echo strpos("I love php, I love php too!","php")
;?>Definition and usage
strpos() The f function finds the first occurrence of a string within another string (case sensitive).
Note: The strpos() function is case-sensitive.
Note: This function is binary safe.
Related functions:
strrpos() - Find the last occurrence of a string in another string (case sensitive)
stripos() - Find the first occurrence of a string in another string (case insensitive)
strripos () - Find the last occurrence of a string in another string (case insensitive)
Syntax
strpos(string,find,start)
| Parameters | Description |
| string | Required. Specifies the string to be searched for. |
| find | Required. Specifies the characters to search for. |
| start | Optional. Specifies the location from which to start the search. |
Technical details
| Return value: | Returns a string within another string The position of the first occurrence, or FALSE if the string is not found. Note: The string position starts from 0, not from 1. |
| PHP version: | 4+ |
Return value problem of function, if it is not found, it will return false. If the substring appears at the beginning, it will return 0. In order to distinguish the returned 0 from false, the equivalent operators === or !== must be used.
01 <?php
02 $mystring = 'abcde';
03 $findme = 'ab';
04 $pos = strpos($mystring, $findme);
05
06 // Note our use of ===. Simply == would not work as expected
07 // because the position of 'ab' was the 0th (first) character.
08 // 这里使用了恒等于 ===，如果使用 == 的话无法得到预期的结果
09 // 因为字符串 ab 是从第0个字符开始的
10 if ($pos === false)
11 {
12 echo "The string '$findme' was not found in the string '$mystring'";
13 }
14 else
15 {
16 echo "The string '$findme' was found in the string '$mystring'";
17 echo " and exists at position $pos";
18 }
19 ?>Program output: The string 'ab' was found in the string 'abcde' and exists at position 0
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