PHP Exercises: Concat two given strings

Last update on May 28 2025 13:04:58 (UTC/GMT +8 hours)

77. Concat Lowercase Strings and Omit Doubles

Write a PHP program to concat two given strings (lowercase). If there are any double character in new string then omit one character.

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that concatenates two strings based on certain conditions
function test($s1, $s2)
{
    // Check if the length of $s1 is less than 1
    if (strlen($s1) < 1)
    {
        // If true, return $s2
        return $s2;
    }

    // Check if the length of $s2 is less than 1
    if (strlen($s2) < 1)
    {
        // If true, return $s1
        return $s1;
    }

    // Check if the last character of $s1 is not equal to the first character of $s2
    if (substr($s1, strlen($s1) - 1, 1) <> substr($s2, 0, 1))
    {
        // If true, concatenate $s1 and $s2
        return $s1 . $s2;
    }
    else
    {
        // If false, concatenate $s1 and the substring of $s2 from the second character
        return $s1 . substr($s2, 1, strlen($s1) - 1);
    }
}

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

Explanation:

Function Definition:

The test function is defined with two parameters:

$s1: the first input string.
$s2: the second input string.

Condition 1: Check if $s1 is Empty:

If $s1 has less than 1 character (i.e., it is empty):

Return $s2.

Condition 2: Check if $s2 is Empty:

If $s2 has less than 1 character (i.e., it is empty):

Return $s1.

Condition 3: Check the Last Character of $s1 and the First Character of $s2:

If the last character of $s1 is not equal to the first character of $s2:

Concatenate $s1 and $s2 directly.

Otherwise (if they are equal):

Concatenate $s1 with $s2, excluding the first character of $s2 (to avoid duplication).

Output:

abcat
PythonPHP
phphp

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to merge two lowercase strings and remove any consecutive duplicate characters from the result.
Write a PHP function to combine two input strings, then scan for and eliminate any double-character occurrences.
Write a PHP program to concatenate two strings and apply a filter to reduce repeated characters in overlapping areas.
Write a PHP script to process lowercase inputs, join them, and employ regex to collapse adjacent duplicates into a single instance.

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