PHP tips: how to replace two variable values without a third variable

PHP skills-solutions to interchange two variable values without third variables

I mentioned the basic methods for exchanging values of two variables in PHP in the Bubble Sort algorithm explanation in PHP. this is because I am mainly talking about Bubble sorting, so I didn't go into details. Now let's take a look at how to exchange two variables in PHP without using the third variable.

Body (For more information, see code comments)

I. substr () & strlen ()

Code:

 '; // Output the original value $. = $ B; // Append the value of $ B to $ a./*** $ B obtains the value of $ a for details: * first use strlen () calculate the length of the string in $ a and $ B respectively. [$ a is the combination of original $ a and $ B.] * use strlen ($ a)-strlen ($ B) the length of the original $ a value is obtained * the length starting from 0 to $ a in the merged $ a using the substr () method, then you can get the original $ a value * $ a and get the $ B value details: * because $ B is already the original value of $ a at the moment, the merged value of $ a is the original value of $ a + original $ B. Therefore, substr () is used to extract the value from the length position of $ B (original $ a) in $, then, if the content is original $ B, the $ B value is paid to $ a for Success */$ B = substr ($ a, 0, (strlen ($) -strlen ($ B); $ a = substr ($ a, strlen ($ B); echo 'value of $ a after Exchange :'. $. ', $ B value :'. $ B ,'
'; // Output result value

Running result:

$ A value before switching: This is A, $ B value: This is B after switching $ a value: This is B, $ B value: This is

II. str_replace ()

Code:

 '; // Output the original value $. = $ B; // Append the value of $ B to $ a $ B = str_replace ($ B, "", $ ); // in $ a (original $ a + $ B), replace $ B with null, and the remaining return value is $ a = str_replace ($ B ,"", $ a); // at this time, $ B is the original $ a value, and $ B (original $ a) is replaced with null in $ a (original $ a + $ B, then the remaining return values are original $ B. The value of $ a after the switch is successful echo :'. $. ', $ B value :'. $ B ,'
'; // Output result value

Running result:

$ A value before switching: This is A, $ B value: This is B after switching $ a value: This is B, $ B value: This is

III. list () & list ()

Code:

 '; // The output original value list ($ B, $ a) = array ($ a, $ B); // The list () function assigns a value to a group of variables with elements in the array. To understand this, I believe you don't need to talk about anything else. echo 'after the exchange, the value of $ a: '. $ a.', the value of $ B: '. $ B ,'
'; // Output result value

Running result:

$ A value before switching: This is A, $ B value: This is B after switching $ a value: This is B, $ B value: This is

IV. exclusive or

Code:

 '; // Output original value/*** original binary: * $ a: 010101000110100001101001011100110010000001101001011100110010000001000001 * $ B: 010101000110100001101001011100110010000001101001011100110010000001000010 ** the following uses bitwise XOR or swapping, for details, refer to the following binary process, */$ a = $ a ^ $ B; // at the moment $ a: 000000000000000000000000000000000000000000000000000000000000000000000011 $ B = $ B ^ $; // at the moment $ B: 010101000110100001101001011100110010000001101001011100110010000001000001 $ a = $ a ^ $ B; // at the moment $ a: 010101000110100001101001011100110010000001101001011100110010000001000010 echo 'the value of $ a after the exchange :'. $. ', $ B value :'. $ B ,'
'; // Output result value

Running result:

$ A value before switching: This is A, $ B value: This is B after switching $ a value: This is B, $ B value: This is

5. plus (+) minus (-) operator

Code:

 '; // Output original value $ a = $ a + $ B; // $ a $ B and value $ B = $ a-$ B; // not explained .. $ a = $ a-$ B; // not explained .. echo 'value of $ a after Exchange :'. $. ', $ B value :'. $ B ,'
'; // Output result value

Running result:

$ A value before switching: 1, $ B value: 2 after switching $ a value: 2, $ B value: 1

Summary

OK, the above is almost all the methods for exchanging two variable values without using the third variable in php. of course, there must be a better one. I am here to discuss it.

In the end, they are all small algorithms. you can study them if you are free.