PHP Exercises: Create a new string from a given string after swapping last two characters

Last update on May 28 2025 13:07:03 (UTC/GMT +8 hours)

78. Swap Last Two Characters in String

Write a PHP program to create a new string from a given string after swapping last two characters.

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that manipulates a string based on its length
function test($s1)
{ 
    // Check if the length of $s1 is greater than 1
    if (strlen($s1) > 1)
    {
        // If true, return a modified string:
        // Concatenate the substring of $s1 from the beginning to the second-to-last character,
        // then append the last character, and finally, append the second-to-last character
        return substr($s1, 0, strlen($s1) - 2) . substr($s1, strlen($s1) - 1, 1) . substr($s1, strlen($s1) - 2, 1);
    }
    else
    {
        // If false (length is less than or equal to 1), return $s1 as is
        return $s1;
    }
}

// Test the 'test' function with different strings, then display the results using echo
echo test("Hello")."\n";
echo test("Python")."\n";
echo test("PHP")."\n";
echo test("JS")."\n";
echo test("C")."\n";
?>

Explanation:

Function Definition:

The function test is defined with a single parameter:

$s1: the input string to manipulate.

Length Check:

The function checks if the length of $s1 is greater than 1.

strlen($s1) > 1

String Manipulation (if condition is true):

If the length of $s1 is greater than 1:

Extracts and concatenates parts of the string as follows:

First Part: substr($s1, 0, strlen($s1) - 2)

This gets the substring from the start of $s1 up to the second-to-last character.

Last Character: substr($s1, strlen($s1) - 1, 1)

This retrieves the last character of the string.

Second-to-Last Character: substr($s1, strlen($s1) - 2, 1)

This retrieves the second-to-last character of the string.

The modified string is formed by concatenating these three parts.

Return Original String (if condition is false):

If the length of $s1 is less than or equal to 1:

The function returns $s1 unchanged.

Output:

Helol
Pythno
PPH
SJ
C

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to swap the last two characters of a string and return the modified string.
Write a PHP function to identify the final two letters and exchange their positions, leaving shorter strings unchanged.
Write a PHP program to manipulate an input string by interchanging its last two characters using substr functions.
Write a PHP script to check string length and, if adequate, reverse the order of the final two characters.

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