php基础31：正则匹配-元字符

<?php

    //2.正则表达式：元字符
    $model = "/php/";
    $string = "php";

    // 1.元字符 [a-z] 匹配任何a-z的字符串
    // []：中括号语法表示，匹配任意一个即可
    $model = "/[abc]/";
    $string = "a";
    echo preg_match($model, $string);

    $model = "/[abc]/";
    $string = "b";
    echo preg_match($model, $string);

    $model = "/[abc]/";
    $string = "a";
    echo preg_match($model, $string);

    $model = "/[abc]/";
    $string = "abdddsssaassas";
    echo preg_match($model, $string);

    $model = "/[abc]/";
    $string = "dddddddasssddddd";
    echo preg_match($model, $string);

    $model = "/[0-9]{3}/";
    $string = "123ffssd";
    echo preg_match($model, $string);

    //备注：[]匹配该范围内的任意一个字符即可

    $model = "/[a-zA-Z0-9_]/";//
    $string = "_";
    echo preg_match($model, $string)."<hr>";

    //2.[^abc]:主意是在中括号内部加^
    //[^abc]表示匹配除了abc，任何一个就可以了
    $model = "/[^abc]/";
    $string = "a";
    echo preg_match($model, $string);

    $model = "/[^abc]/";
    $string = "b";
    echo preg_match($model, $string);

    $model = "/[^abc]/";
    $string = "c";
    echo preg_match($model, $string);

    $model = "/[^abc]/";
    $string = "abcsabc";
    echo preg_match($model, $string)."<hr>";

    //3. \w 匹配任何包含a-zA-Z0-9和下划线的字符串
    // \w <=> [a-zA-Z0-9_]
    $model = "/\w/";
    $string = "c";
    echo preg_match($model, $string);

    $model = "/\w/";
    $string = "&";
    echo preg_match($model, $string);

    $model = "/\w/";
    $string = "0&";
    echo preg_match($model, $string)."<hr>";

    //4. \W（与小写的要区分）
    // \W 与 \w 正好相反
    $model = "/\W/";
    $string = "&";
    echo preg_match($model, $string);

    $model = "/\W/";
    $string = "0&";
    echo preg_match($model, $string);

    $model = "/\W/";
    $string = "s";
    echo preg_match($model, $string)."<hr>";

    //05. \d 匹配任意数字
    // 与 [0-9]相同
    $model = "/\d/";
    $string = "11";
    echo preg_match($model, $string);

    $model = "/\d/";
    $string = "$";
    echo preg_match($model, $string);

    $model = "/\d/";
    $string = "AS";
    echo preg_match($model, $string)."<HR>";

    //06：\D 与 \d 相反
    // 与 [^0-9]相同
    $model = "/\D/";
    $string = "$0";
    echo preg_match($model, $string);

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

    //07：\s 匹配任何空白字符
    $model = "/\s/";
    $string = "$0";
    echo preg_match($model, $string);

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

    // \S 与 \s 相反
    $model = "/\S/";
    $string = " 0";
    echo preg_match($model, $string)."<hr>";

    //08: \b 表示到达了单词的边界，边界可以理解为空格
    // \B 表示没有到达空格
    $model = "/php\b/";
    $string = "php";
    echo preg_match($model, $string);

    $model = "/php\b/";
    $string = "php，";
    echo preg_match($model, $string);

    $model = "/php\b/";
    $string = "phpzzz";
    echo preg_match($model, $string);

    $model = "/php\b/";
    $string = "php,gggggg";
    echo preg_match($model, $string)."<hr>";

    //09: \匹配正则中的特殊字符
    // 比如+是正则里面的特殊字符，如果要匹配特殊字符的话，必须加上 \
    $model = "/ph\+p/";
    $string = "ph+p";
    echo preg_match($model, $string);

    $model = "/ph\+p/";
    $string = "ccccph+pdddd";
    echo preg_match($model, $string)."<hr>";
?>