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我是初学者，我们的教授告诉我们，我们需要解释这段代码的目的是什么。我知道这是为了排序，但我想简要解释一下。有人可以帮我吗？

<?php
function descending(){
    $num1 = $_GET['num1'];
    $num2 = $_GET['num2'];
    $num3 = $_GET['num3'];

    if ($num1 < $num2) {
        $temp = $num1;
        $num1 = $num2;
        $num2 = $temp;
    }
    if ($num1 < $num3) {
       $temp = $num1;
       $num1 = $num3;
       $num3 = $temp;
    }
    if ($num2 < $num3) {
       $temp = $num2;
       $num2 = $num3;
       $num3 = $temp;
    }
    echo "<br>";
    echo $num1a . " , " . $num2a . " , " . $num3a;
    echo "<br>";

?>
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1 回答 1

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递减 3 数字的概念是通过将第一个数字与其他两个数字进行比较，并且第一个数字应该大于其他数字，因此如果第二个数字大于交换到第一个数字，我们将第一个数字与第二个数字进行比较，同样适用于第一个数字和第三个数字之后处理第一个数字将大于二。检查剩余的两个变量并再次比较在第二个变量中分配更大的数字。这样它是递减的。

<?php 
function descending(){
    $num1 = $_GET['num1'];    // Let suppose $num1 = 1
    $num2 = $_GET['num2'];    // Let suppose $num2 = 2
    $num3 = $_GET['num3'];    // Let suppose $num3 = 3


    if ($num1 < $num2) {     // here $num1 (1) is less than $num2(2)
        $temp = $num1;       // $temp(2) 
        $num1 = $num2;       // copy $temp(2) to $num1(2)
        $num2 = $temp;       // this process swap $num1(2) and $num(1)
    }
    if ($num1 < $num3) {     // here $num1(2) and $num3(3) which is less so swap
        $temp = $num1;
        $num1 = $num3;
        $num3 = $temp;       //After swap $num1(3) & $num3(2)      

    }

    //now at this time $num1 greatest among other two variable

    if ($num2 < $num3) {   //$num2(1) and $num3(2) so swap
        $temp = $num2;
        $num2 = $num3;
        $num3 = $temp;     // this way $num2 will be greater
    }

    echo "<br>";
    //first error: After descending value store in $num1, $num2, and $num3
    //not in $num1a, $num2a, and $num3a these variable.
    echo $num1 . " , " . $num2 . " , " . $num3; 
    echo "<br>";
 }  // second error missing this curly bracket.
?>

希望你能理解并忽略我糟糕的英语。快乐编码:)

于 2019-07-04T19:26:01.657 回答