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


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:

    Flowchart: Create a new string from a given string after swapping last two characters.

    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.

    PHP Code Editor:



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    Previous: Write a PHP program to concat two given strings (lowercase). If there are any double character in new string then omit one character.
    Next: Write a PHP program to check if a given string begins with 'abc' or 'xyz'. If the string begins with 'abc' or 'xyz' return 'abc' or 'xyz' otherwise return the empty string.

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