php基础30：正则匹配-量词

Posted 2020-08-25

<?php

    //正则表达式
    
    //1.第一个正则表达式
    if("a"=="a"){
        echo "equal";
    }else{
        echo "noequal";
    }
    echo "<hr>";

    //第一个参数表示匹配模式，第二个参数匹配的字符串
    echo (preg_match(‘/php/‘,"php"));
    echo (preg_match(‘/php/‘,"php222"));
    echo (preg_match(‘/php/‘,"p2h2p2"));

    $modle = "/php/";
    $string = "php";
    if (preg_match($modle, $string)) {
        echo "success";
    }else{
        echo "fail";
    };
    echo "<hr>";

    //什么叫做匹配？：按照模式来匹配
    //匹配与相等是不同的概念

    //2.量词+：匹配任何至少包括一个前导字符串（1个或者多个）
    // 前导：前面一个字符，+的前导是h
    // h+ 的意思是只要要包括1个h
    $model = "/ph+p/";
    $string = "phhhhhhhp";
    echo(preg_match($model, $string));//1

    $model = "/ph+p/";
    $string = "phhhgggggggggp";
    echo(preg_match($model, $string));//0

    $model = "/ph+p/";
    $string = "pp";
    echo(preg_match($model, $string))."<hr>";//0


    // 3.量词*：匹配任包括0个或者多个前导字符串（0个或者多个）
    // * 虽然可以是0个，但是前导字符不能更改，更就不匹配了
    $model = "/ph*p/";
    $string = "php";
    echo(preg_match($model, $string));//1

    $model = "/ph*p/";
    $string = "pp";
    echo(preg_match($model, $string));//1

    $model = "/ph*p/";
    $string = "pbbbbp";
    echo(preg_match($model, $string));//0
    echo "<hr>";

    // 3.量词?：匹配任何包含1个或者0个前导字符
    $model = "/ph?p/";
    $string = "pp";
    echo(preg_match($model, $string));//1

    $model = "/ph?p/";
    $string = "php";
    echo(preg_match($model, $string));//1

    $model = "/ph?p/";
    $string = "phhhp";
    echo(preg_match($model, $string))."<hr>";//0

    //4.量词（.）匹配任意一个字符
    //n个点匹配n个任意字符
    $model = "/p.p/";
    $string = "php";
    echo(preg_match($model, $string));//1

    $model = "/p..p/";
    $string = "phrp";
    echo(preg_match($model, $string));//1

    $model = "/p..p/";
    $string = "php";
    echo(preg_match($model, $string));//0

    $model = "/p..p/";
    $string = "phhhp";
    echo(preg_match($model, $string))."<hr>";//0

    //5.(.与*)的配合
    //（.*）表示任意前导字符，0个或者多个
    $model = "/p.*p/";
    $string = "php";
    echo(preg_match($model, $string));//1

    $model = "/p.*p/";
    $string = "phhhhhhp";
    echo(preg_match($model, $string));//1

    $model = "/p.*p/";
    $string = "pp";
    echo(preg_match($model, $string))."<hr>";//1

    // 6.量词{x}：表示前导必须是3个
    $model = "/ph{3}p/"; // h{3}匹配3个h
    $string = "phhhp";
    echo(preg_match($model, $string));//1

    $model = "/ph{3}p/";
    $string = "php";
    echo(preg_match($model, $string))."<hr>";//0

    //7.量词{x,y}：匹配x-y个前导字符串
    $model = "/ph{3,5}p/";
    $string = "phhhp";
    echo(preg_match($model, $string));//1

    $model = "/ph{3,5}p/";
    $string = "phhhhp";
    echo(preg_match($model, $string));//1

    $model = "/ph{3,5}p/";
    $string = "phhhhhp";
    echo(preg_match($model, $string))."<hr>";//1

    //8.量词{x,}：匹配至少x个前导字符串
    $model = "/ph{3,}p/";
    $string = "phhhp";
    echo(preg_match($model, $string));//1

    $model = "/ph{3,}p/";
    $string = "phhp";
    echo(preg_match($model, $string));//0

    $model = "/ph{3,}p/";
    $string = "phhhhp";
    echo(preg_match($model, $string))."<hr>";//1

    //9.$：匹配字符串的行尾
    //$一般加载字符串的尾巴上，表示从尾巴开始匹配（以xxx结尾）
    $model = "/php/";
    $string = "cccccccccccccccc php ccccccccccc";
    echo(preg_match($model, $string));//1

    $model = "/php$/";
    $string = "cccccccccccccccc php ccccccccccc";
    echo(preg_match($model, $string));//0

    $model = "/php$/";
    $string = "cccccccccccccccccccccccccccphp";
    echo(preg_match($model, $string))."<hr>";//1

    //10. ^ 表示从头开始匹配
    // 表示 以 xxx 开始
    $model = "/^php/";
    $string = "cccccccccccccccccccccccccccphp";
    echo(preg_match($model, $string));//0

    $model = "/^php/";
    $string = "phpcccccccccccccccccccccccccccphp";
    echo(preg_match($model, $string));//1

    //如果^和$一起使用，表示匹配一模一样的，那就使用==即可
    $model = "/^php$/";
    $string = "phpcccccccccccccccccccccccccccphp";
    echo(preg_match($model, $string))."<hr>";//1

    // 10. | : 匹配字符串的左边或者右边
    //条件选择符号
    $model = "/php|jsp/";
    $string = "php";
    echo(preg_match($model, $string));//1

    $model = "/php|jsp/";
    $string = "jsp";
    echo(preg_match($model, $string));//0

    $model = "/php|jsp/";
    $string = "asp";
    echo(preg_match($model, $string));//0

    $model = "/php|jsp|asp/";
    $string = "asp";
    echo(preg_match($model, $string))."<hr>";//1

    // 11. () : 包围一个字符分组或者
    //讲到后面才可以理解

?>