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

PHP Basic Algorithm: Exercise-5 with Solution

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:

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