<?php
echo strpos("I love php, I love php too!","php")
;?>

strpos(string,find,start)

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    ?>

The string 'ab' was found in the string 'abcde' and exists at position 0