PHP Exercises: Create a new string using the two middle characters of a given string of even length

PHP Basic Algorithm: Exercise-70 with Solution

Write a PHP program to create a new string using the two middle characters of a given string of even length (at least 2).

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that extracts a substring of two characters from the middle of the input string
function test($s1)
{ 
    // Calculate the starting index to obtain the middle two characters
    return substr($s1, strlen($s1)/2 - 1, 2); 
}

// Test the 'test' function with different strings and display the results
echo test("Hell")."\n";
echo test("JS")."\n";
echo test("  ")."\n";
?>

Explanation:

• Function Definition:
• A function named test is defined, which takes one parameter, $s1, representing the input string.
• Calculating the Starting Index:
• The function uses the strlen($s1)/2 - 1 expression to calculate the starting index for extracting a substring.
• This calculation determines the middle of the string:
• strlen($s1)/2 finds the midpoint.
• Subtracting 1 adjusts the index to start from one character before the midpoint.
• Extracting the Substring:
• The function then calls substr($s1, strlen($s1)/2 - 1, 2):
• This extracts a substring starting at the calculated index and retrieves 2 characters from that point.

Output:

el
JS

Flowchart:

PHP Code Editor:

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