This article describes the string matching algorithm implemented by PHP—————————————————————————————————————————————————————————————————————————————————————————————————————————————————— Share it for your reference, as follows:
The Sunday algorithm is a string pattern matching proposed by Daniel in 1990. The core idea is:During the matching process, when a pattern string finds a mismatch, the algorithm can skip as many characters as possible to perform the next match, thereby improving the matching efficiency.
<?php
/*
*@param $pattern pattern string
*@param $text string to be matched
*/
function mySunday($pattern = '',$text = ''){
if(!$pattern || !$text) return false;
$pattern_len = mb_strlen($pattern);
$text_len = mb_strlen($text);
if($pattern_len >= $text_len) return false;
$i = 0;
for($i = 0; $i < $pattern_len; $i++){ //Assemble an array with characters in pattern as subscript $shift[$pattern[$i]] = $pattern_len - $i;
}
while($i <= $text_len - $pattern_len){
$nums = 0; //The number of characters on the match while($pattern[$nums] == $text[$i + $nums]){
$nums++;
if($nums == $pattern_len){
return "The first match index is $i\n";
}
}
if($i + $pattern_len < $text_len && isset($shift[$text[$i + $pattern_len]])){ //Judge whether the character after the mode string is in the mode string $i += $shift[$text[$i + $pattern_len]]; //Align the character }else{
$i += $pattern_len; //Slide the pattern_len bit directly }
}
}
$text = "I am testing mySunday on sunday!";
$pattern = "sunday";
echo mySunday($pattern,$text);
Running results:
The first match index is 25
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