PHP Exercises: Create a new string taking 3 characters from the middle of a given string at least 3

Last update on December 20 2024 10:26:40 (UTC/GMT +8 hours)

Write a PHP program to create a new string taking 3 characters from the middle of a given string at least 3.

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that extracts a substring of length 3 from the middle of the input string
// If the length of the string is odd, the middle is calculated as (length - 1) / 2 - 1
// If the length is even, the middle is calculated as length / 2 - 1
function test($s1)
{ 
   // Use substr to extract a substring of length 3 from the middle of the string
   // If the length is odd, calculate the middle as (length - 1) / 2 - 1
   // If the length is even, calculate the middle as length / 2 - 1
   return substr($s1, (strlen($s1) - 1) / 2 - 1, 3);
}

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

Explanation:

Function Definition:

A function named test is defined with a single parameter:

$s1: the input string.

Substring Extraction:

The function calculates the starting index for extracting a 3-character substring from the middle of the input string:

If the string length is odd, (strlen($s1) - 1) / 2 - 1 gives the starting position of the middle three characters.
If the string length is even, the same formula approximates the middle.

substr($s1, (strlen($s1) - 1) / 2 - 1, 3) extracts three characters starting from the calculated middle index.

Output:

ell
yth
abc

Flowchart:

PHP Code Editor:

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