php实现的简单压缩英文字符串的代码

2019-10-29 15:29php教程网 PHP教程

一直在找压缩字符串的算法, 不知道是不是关键词选择的不对, 找不到适合的,自己写了一对连续字符压缩,(如 vvvv -> 4v) 不过实用效果不太好(压缩比低,效率却不高), 暂且丢上来晒晒吧

PHP,适应于上帖简单加密后的密文

<?php
//replacement来自上个版本的加密替换

     function compress_func($match) {return strlen($match[0]).$match[0]{0};}

     function uncompress_func($match) {return str_repeat($match[2], $match[1]);}

     function compress($str) {
        $i = 0;
        $pattern = array();
        while(isset($replacement{$i})) array_push($pattern, "/".$replacement{$i++}."{2,}/");
        return preg_replace_callback($pattern, "compress_func", $str);
    }

     function uncompress($str) {
        return preg_replace_callback("/(d+)(w)/", "uncompress_func", $str);
    }
?>

AWK,通用格式

复制代码代码如下:

#!/bin/awk
function compress(str, _ARGVEND_, str_out, str_len, i, s, l) {
    str_out = "";
    str_len = length(str);
    s = "";
    l = 1;
    for(i =1; i <= str_len; i++) {
        if(substr(str, i, 1) == s) l++;
        else {
            if(s != "") {
                if(l > 1) str_out=str_out""l
                str_out=str_out""s;
            }
            s = substr(str, i, 1);
            l = 1;
        }
    }
    return str_out;
}
function uncompress(str, _ARGVEND_, str_out, str_len, i, c) {
    str_out = "";
    str_len = length(str);
    for(i =1; i <= str_len; i++) {
        c = 0;
        while(substr(str, i, 1)~/[0-9]/) {
            c = c*10+substr(str, i, 1);
            i++;
        }
        if(c < 1) c = 1;
        while(c--) str_out = str_out""substr(str, i, 1);
    }
    return str_out;
}