PHP Exercises: Create a new string where 'if' is added to the front of a given string

Last update on December 20 2024 10:20:22 (UTC/GMT +8 hours)

Write a PHP program to create a new string where 'if' is added to the front of a given string. If the string already begins with 'if', return the string unchanged.

Sample Solution:

PHP Code :

<?php
// Define a function named "test" that takes a parameter $s
function test($s)
{
    // Check if the length of $s is greater than or equal to 2 AND if the substring of $s from index 0 to 1 is equal to "if"
    if (strlen($s) >= 2 && substr($s, 0, 2) == "if")
    {
        // If true, return $s as it is
        return $s;
    }

    // If false, prepend "if " to $s and return the result
    return "if " . $s;
}

// Call the test function with argument "if else" and echo the result
echo test("if else") . "\n";

// Call the test function with argument "else" and echo the result
echo test("else") . "\n";

// Call the test function with argument "if" and echo the result
echo test("if") . "\n";
?>

Explanation:

Function Definition:

The function test is defined with a single parameter $s.

Condition Check:

The function checks two conditions:

The length of $s is at least 2 characters (strlen($s) >= 2).
The first two characters of $s are "if" (substr($s, 0, 2) == "if").

If both conditions are true, it returns $s unchanged.

Return Value:

If either condition is false, the function prepends "if " to $s and returns the modified string.

Function Calls and Output:

First Call: echo test("if else")

The string starts with "if", so it returns "if else" unchanged.

Second Call: echo test("else")

The string does not start with "if", so it returns "if else".

Third Call: echo test("if")

The string starts with "if", so it returns "if" unchanged.

Output:

if else
if else
if

Flowchart:

PHP Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a PHP program to check a given integer and return true if it is within 10 of 100 or 200.
Next: Write a PHP program to remove the character in a given position of a given string. The given position will be in the range 0..string length -1 inclusive.