PHP 中的交換-php教程-PHP中文網

在本文中，我們將學習 PHP 中的數位交換。我們將學習如何定義交換、如何編寫程式碼來交換兩個數字、如何交換兩個以上數字和三個數字以及如何在有或沒有臨時變數的情況下交換數字等等。

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「PHP 中的交換是一個定義為值交換的術語。」

交換兩個數字是使用或不使用臨時變數交換兩個值的過程。我希望這些例子對所有想要學習交換概念的程式設計師有所幫助。

如何在 PHP 中交換兩個數字？

交換號碼有兩種方法。這些數字包含數值。

用臨時變數交換兩個數字。
在沒有臨時變數的情況下交換兩個數字。

假設我們有一個變數的值為 10，

數字1 = 10;

另一個變數的值為 20，

數字2 = 20;

交換這兩個數字，結果應該是，

數字1 =20

數字2= 10

這可以透過使用第三個臨時變數來實現，也可以不使用臨時變數。可以使用 +、-、* 和 / 運算子交換兩個數字。

1.用臨時變數交換兩個數字

代碼：

<?PHP
// Example of swapping of two numbers using a temporary variable
// Declaring two variables
$num1 = 100;
$num2 = 200;
// using echo statement print the variables before swapping two numbers
echo "<br>"."Before Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<hr>";
// declaring temporary variable to be zero
$temp = 0;
// performing swap of numbers
$temp = $num1;
$num1 = $num2;
$num2 = $temp;
//using the echo statement print the variables after swapping the numbers
echo "<br>"."After Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
?>

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PHP 中的交換

2.不使用臨時變數交換兩個數字

代碼：

<?php
// Example of swapping of two numbers without using a temporary variable
// Declaring two variables
$num1 = 100;
$num2 = 200;
// using echo statemnt print the variables before swapping two numbers
echo "<br>"."Swap done without using temparory variable";
echo "<hr>";
echo "<br>"."Before Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<hr>";
// performing swap of numbers
$num1 = $num1 - $num2;
$num2 = $num1 + $num2;
$num1 = $num2 - $num1;
//using the echo statement print the variables after swapping the numbers
echo "<br>"."After Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
?>

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輸出：

PHP 中的交換

3.使用 list() 和 array() 等函數交換兩個數字

代碼：

<?php
// Example of swapping of two numbers using list() with array()
// Declaring two variables
$num1 = 100;
$num2 = 200;
// using echo statement print the variables before swapping two numbers
echo "<br>"."Swap done without using predefined functions";
echo "<hr>";
echo "<br>"."Before Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<hr>";
// performing swap of numbers
list($num1, $num2) = array($num2, $num1);
//using the echo statement print the variables after swapping the numbers
echo "<br>"."After Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
?>

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如何在 PHP 中交換三個數字？

交換號碼有兩種方法。這些數字包含數值。

用臨時變數交換三個數字。
在沒有臨時變數的情況下交換三個數字。

1.使用臨時變數交換三個數字

現在我們已經學會了兩個數字的交換，我們已經學會了三個數字的交換。以下範例示範了臨時（temp）變數如何交換三個數字。

代碼：

<?php
// Example of swapping three numbers using temporary variable
// Declaring three variables
$num1 = 100;
$num2 = 200;
$num3 = 300;
// using echo statement print the variables before swapping three numbers
echo "<br>"."Swap done without using temporary variable";
echo "<hr>";
echo "<br>"."Before Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<br>"."Value of third number is  = ". $num3;
echo "<hr>";
// performing swap of numbers
//assign first number the total of three numbers
$temp = $num1;
$num1 = $num2;
$num2 = $num3;
$num3 = $temp;
//using the echo statement print the variables after swapping the numbers
echo "<br>"."After Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<br>"."Value of third number is  = ". $num3;
?>

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2.不使用臨時變數交換三個數字

邏輯是計算總和並將其分配給 $num1 變數。

然後，

計算$num1的值，將該值賦給$num2，

計算$num2的值，將該值賦給$num3，

計算$num3的值，並將這個值再賦給$num1。

代碼：

<?php
// Declaring three variables
$num1 = 100;
$num2 = 200;
$num3 = 300;
// using echo statement print the variables before swapping three numbers
echo "<br>"."Swap done without using temporary variable";
echo "<hr>";
echo "<br>"."Before Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<br>"."Value of third number is  = ". $num3;
echo "<hr>";
// performing swap of numbers
//assign first number the total of three numbers
$num1 = $num1 + $num2 + $num3;
$num2 = $num1 - ($num2 + $num3);
$num3 = $num1 - ($num2 + $num3);
$num1 = $num1 - ($num2 + $num3);
//using the echo statement print the variables after swapping the numbers
echo "<br>"."After Swap";
echo "<hr>";
echo "<br>"."Value of first number is  = ". $num1;
echo "<br>"."Value of second number is  = ". $num2;
echo "<br>"."Value of third number is  = ". $num3;
?>

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輸出：