PHP Exercises: Create a new string using the first and last n characters from a given string of length at least n

Last update on May 28 2025 13:05:00 (UTC/GMT +8 hours)

72. Concat First and Last n Characters

Write a PHP program to create a new string using the first and last n characters from a given string of length at least n.

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that concatenates the first 'n' characters and the last 'n' characters of the input string
function test($s1, $n)
{ 
   // Use substr to extract the first 'n' characters and concatenate with the last 'n' characters of the input string
   return substr($s1, 0, $n) . substr($s1, strlen($s1) - $n, $n);
}

// Test the 'test' function with different strings and 'n' values, then display the results using echo
echo test("Hello", 1)."\n";
echo test("Python", 2)."\n";
echo test("on", 1)."\n";
echo test("o", 1)."\n";
?>

Explanation:

Function Definition:

A function named test is defined, which takes two parameters:

$s1: the input string.
$n: the number of characters to extract from the start and end of the string.

Concatenation of Substrings:

The function uses substr to concatenate parts of the string:

substr($s1, 0, $n) extracts the first n characters of $s1.
substr($s1, strlen($s1) - $n, $n) extracts the last n characters.

The two substrings are concatenated and returned as a single string.

Output:

Ho
Pyon
on
oo

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to output a new string formed by concatenating the first n and last n characters of the input string.
Write a PHP function to extract the beginning and ending segments of a string as determined by an integer n and join them together.
Write a PHP program to slice an input string into two parts based on the parameter n and concatenate the parts.
Write a PHP script to check string length and then create a new string from its first and last n letters.

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