Swapping in PHP

Introduction to Swapping in PHP

In this article, we will learn the swapping of numbers in PHP. We will learn how we define swapping, we will learn how to code to swap two numbers, how to swap more than two numbers and three numbers and how to swap numbers with or without temporary variables and more.

Let us begin with the definition first.

“Swapping in PHP is a term defined as interchanging of values.”

Swapping of two numbers is a process to exchange two values using or without using a temporary variable. I hope these examples are useful to all the programmers who want to learn the concept of swapping.

How to Swap Two Numbers in PHP?

There are two ways to swap numbers. These numbers hold numerical values.

• Swapping two numbers with a temporary variable.
• Swapping two numbers without a temporary variable.

Suppose we have one variable holding a value 10,

number1 = 10 ;

And the other variable holding a value 20,

number2 = 20;

On swapping of these two numbers, the result should be,

number1 =20

number2= 10

This is possible with the use of the third temporary variable and without a temporary variable also. Swapping two numbers can be done using +, -, *, / operators.

1. Swapping Two Numbers with a Temporary Variable

Code:

// Example of swapping of two numbers using a temporary variable
<?php
// 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;
?>

Output:

2. Swapping Two Numbers without Temporary Variable

Code:

<?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;
?>

Output:

3. Swapping of two numbers using a function like list() with array()

Code:

<?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;
?>

Output:

How to Swap Three Numbers in PHP?

There are two ways to swap numbers. These numbers hold numerical values.

• Swapping three numbers with a temporary variable.
• Swapping three numbers without a temporary variable.

1. Swapping Three Numbers using Temporary Variable

Now that we have learned swapping of two numbers, in a similar way we learn swapping of three numbers now. The following example demonstrates how a temporary(temp) variable is used to swap three numbers.

Code:

<?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;
?>

Output:

2. Swapping Three Numbers Without Using Temporary Variable

The logic here is to calculate the total sum and assign it to a $num1 variable.

And then,

calculate the value of $num1, assign this value to $num2,

calculate the value of $num2, assign this value to $num3,

calculate the value of $num3, and assign this value to $num1 again.

Code:

<?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;
?>

Output:

Conclusion

I hope this article is useful to all the programmers who wish to learn swapping of numbers. This article has both swappings of two and three numbers with appropriate examples. These examples if practiced will help you learn the concept and help you remember the logic as well.

Recommended Articles

This is a guide to Swapping in PHP. Here we discuss how to swap two or three numbers with or without using temporary variables along with its examples. You may also look at the following articles to learn more –

1. Sessions in PHP
2. Patterns in PHP
3. Cookie in PHP
4. Overloading in PHP