Android programmers learn PHP development (20)-Arrays (2) Multi-dimensional arrays and practical applications-PhpStorm-PHP Tutorial-php.cn

Android programmers learn PHP development (20)-Arrays (2) Multi-dimensional arrays and practical applications-PhpStorm

黄舟

Release： 2023-03-06 10:16:02

Original

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In PHP development, a large proportion of us are operating arrays, so learning arrays is very important~~

<?php
    /**
     * 二维数组
     */
    $group = array(
        array("name"=>"iwanghang", "age"=>18, "sex"=>"男", "email"=>"iwanghang@qq.com"),  // $group[0]
        array("name"=>"queen", "age"=>14, "sex"=>"女", "email"=>"queen@qq.com"), // $group[1]
        array("name"=>"king", "age"=>55, "sex"=>"男", "email"=>"king@qq.com"), // $group[2]
        "four"=>array("name"=>"xiaoming", "age"=>8, "sex"=>"男", "email"=>"xiaoming@qq.com")
    );
    var_dump($group[1]); // 打印结果 ： array(4) { ["name"]=> string(5) "queen" ["age"]=> int(14)
                         // ["sex"]=> string(3) "女" ["email"]=> string(12) "queen@qq.com" }
    echo "<br>";
    var_dump($group[1]["name"]); // 打印结果 ： string(5) "queen"
    echo "<br>";
    var_dump($group[2]["age"]); // 打印结果 ： int(55)
    echo "<br>";
    var_dump($group["four"]["email"]); // 打印结果 ： string(15) "xiaoming@qq.com"
    echo "<br>";

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<?php
    /**
     * 销毁指定下标Demo
     * isset 检测变量是否存在
     * unset 销毁指定的变量
     */
    echo &#39;---------- $arr = ["one", "two", "three". "four"]; ----------<br>&#39;;
    $arr = ["one", "two", "three", "four"];

    echo &#39;---------- isset($arr[2]) ----------<br>&#39;;
    if (isset($arr[2])){ // 打印结果：存在
        echo "存在";
    }else{
        echo "不存在";
    }
    echo "<br>";

    echo &#39;---------- print_r($arr) ----------<br>&#39;;
    print_r($arr); // 打印结果：Array ( [0] => one [1] => two [2] => three [3] => four )
    echo "<br>";

    echo &#39;---------- unset($arr[2]) ----------<br>&#39;;
    unset($arr[2]);
    if (isset($arr[2])){ // 打印结果：不存在
    echo "存在";
    }else{
        echo "不存在";
    }
    echo "<br>";

    echo &#39;---------- print_r($arr) ----------<br>&#39;;
    print_r($arr); // 打印结果：Array ( [0] => one [1] => two [3] => four )
    echo "<br>";

    echo &#39;---------- $arr[2] = null ----------<br>&#39;;
    $arr[2] = null;
    if (isset($arr[2])){ // 打印结果：不存在
        echo "存在";
    }else{
        echo "不存在";
    }
    echo "<br>";

    echo &#39;---------- print_r($arr) ----------<br>&#39;;
    print_r($arr); // 打印结果：Array ( [0] => one [1] => two [3] => four [2] => )
    echo "<br>";

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<?php
    /**
     * 猴子选大王
     * xdw 选大王
     * count($arr) 数组下标
     */

    xdw(88,5); // 30只猴子，每3只出局1只

    function xdw($m, $n){
        $arr = array();

        $a = "a";

        for ($i=0; $i<$m; $i++){
            $arr[] = $a++;
        }

        print_r($arr);

        $i = 0;
        while (count($arr)>1){
            if ($i % $n == 0){
                echo $i."除以".$n."余数为0,所以删除".$arr[$i]."<br>";
                unset($arr[$i]);
            }else{
                $arr[] = $arr[$i];
                print_r($arr);
                echo "<br>";
                unset($arr[$i]);
            }
            $i++;
        }

        print_r($arr);
    }

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