KMP字符串模式匹配算法实现（php)

用php实现KMP字符串模式匹配算法

<?php

// KMP算法实现

function indexOf($target,$pattern,$start){
if($target && $pattern && strlen($target)>strlen($pattern)){
echo "target:$target<br/>pattern:$pattern<br/>";
$i = $start;
$j = 0;
$next = getNext($pattern);
while ($i<strlen($target)){
if ($j==-1||$target{$i}==$pattern{$j}){
$i++;$j++;
}else
$j = $next[$j];
//echo "i:$i,j:$j<br/>";
if ($j==strlen($pattern))
return 'offset: '.($i-$j);
}

}
return -1;
}

// 获取模式串的next数组的函数
function getNext($pattern){
$j=0;$k=-1;
$next[0] = -1;

while ($j<strlen($pattern)-1){
if ($k==-1||$pattern{$j} == $pattern{$k}){
$k++;$j++;
$next[$j] = $k;
}else
$k = $next[$k];
}

return $next;

}

$strs = "abcabdcdbabcacdabcabcde";
$mystr = "abcabc";

echo indexOf($strs,$mystr,0);