


PHP Tips: Solution to Swap Two Variable Values Without Using a Third Variable
Foreword
Last time in the article "Detailed Explanation of PHP Bubble Sort Algorithm", I mentioned the basic method of exchanging the values of two variables in PHP. Because I mainly talked about bubble sort, I didn't go into it in depth. So today here we will take a look at how to achieve the purpose of exchanging two variables without using a third variable in PHP.
Text (see code comments for explanation)
1. substr() && strlen()
Code:
<?php /** * 双方变量为字符串时,可用交换方法一 * 使用substr()结合strlen()两个方法达到交换变量值得目的 */$a = "This is A"; // a变量原始值$b = "This is B"; // b变量原始值echo '交换之前 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出原始值$a .= $b; // 将$b的值追加到$a中 /** * $b得到$a值详解: * 先通过strlen()分别计算出$a和$b中字符串的长度【此时$a是原始$a和$b的合值】 * 通过strlen($a)-strlen($b)即可得出原始$a的值长度 * 在通过substr()方法在合并后的$a中从0开始截取到$a的长度,那么即可得到原始$a的值 * $a得到$b值详解: * 由于此刻$b已经是$a的原始值了,而$a合并后的值为原始$a+原始$b的值,故用substr()在$a中从$b(原始$a)长度位置截取,则去的内容则为原始$b,则将$b值付给$a成功 */$b = substr($a,0,(strlen($a)-strlen($b)));$a = substr($a, strlen($b));echo '交换之后 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出结果值
Run result:
交换之前 $a 的值:This is A, $b 的值:This is B 交换之后 $a 的值:This is B, $b 的值:This is A
2. str_replace()
<?php/** * 双方变量为字符串时,可用交换方法二 * 使用str_replace()方法达到交换变量值得目的 * 此方法较第一种,逻辑上稍微简单点 */$a = "This is A"; // a变量原始值$b = "This is B"; // b变量原始值echo '交换之前 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出原始值$a .= $b; // 将$b的值追加到$a中$b = str_replace($b, "", $a); // 在$a(原始$a+$b)中,将$b替换为空,则余下的返回值为$a$a = str_replace($b, "", $a); // 此时,$b为原始$a值,则在$a(原始$a+$b)中将$b(原始$a)替换为空,则余下的返回值则为原始$b,交换成功echo '交换之后 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出结果值E
Run results:
交换之前 $a 的值:This is A, $b 的值:This is B 交换之后 $a 的值:This is B, $b 的值:This is A
3, list () && list ()
code:
<?php/** * 双方变量为字符串时,可用交换方法三 * 使用list()和array()方法达到交换变量值得目的 * 此方法较第一、二种,代码最简洁 */$a = "This is A"; // a变量原始值$b = "This is B"; // b变量原始值echo '交换之前 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出原始值list($b,$a) = array($a,$b); // list() 函数用数组中的元素为一组变量赋值。了解这个,相信其他的不用我多说了吧echo '交换之后 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出结果值
Run results:
交换之前 $a 的值:This is A, $b 的值:This is B 交换之后 $a 的值:This is B, $b 的值:This is AE
<?php/** * 双方变量为字符串或者数字时,可用交换方法四 * 使用异或运算 */$a = "This is A"; // a变量原始值$b = "This is B"; // b变量原始值echo '交换之前 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出原始值/** * 原始二进制: * $a:010101000110100001101001011100110010000001101001011100110010000001000001 * $b:010101000110100001101001011100110010000001101001011100110010000001000010 * * 下面主要使用按位异或交换,具体请参照下列给出的二进制过程, */$a=$a^$b; // 此刻$a:000000000000000000000000000000000000000000000000000000000000000000000011$b=$b^$a; // 此刻$b:010101000110100001101001011100110010000001101001011100110010000001000001$a=$a^$b; // 此刻$a:010101000110100001101001011100110010000001101001011100110010000001000010echo '交换之后 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出结果值
Running result:
交换之前 $a 的值:This is A, $b 的值:This is B 交换之后 $a 的值:This is B, $b 的值:This is A
5. Add (+) minus (-) operator
🎜🎜🎜Code: 🎜<?php/** * 双方变量为数字时,可用交换方法五 * 使用加减运算符,相当于数学运算了^_^ */$a = "This is A"; // a变量原始值$b = "This is B"; // b变量原始值echo '交换之前 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出原始值$a=$a+$b; // $a $b和值$b=$a-$b; // 不解释..$a=$a-$b; // 不解释..echo '交换之后 $a 的值:'.$a.', $b 的值:'.$b,'<br>'; // 输出结果值🎜Running result: 🎜🎜
交换之前 $a 的值:1, $b 的值:2交换之后 $a 的值:2, $b 的值:1🎜🎜Summary🎜🎜ok, the above is almost the same in php There are no methods of exchanging the values of two variables without the help of a third variable. Of course, there must be a better way, and I am just trying to inspire others here. 🎜🎜In the end, they are all small algorithms, and you can study them yourself when you have time. 🎜

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PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

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PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

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