PHP Exercises: Check if a given string begins with 'abc' or 'xyz'

Last update on December 20 2024 10:20:37 (UTC/GMT +8 hours)

Write a PHP program to check if a given string begins with 'abc' or 'xyz'. If the string begins with 'abc' or 'xyz' return 'abc' or 'xyz' otherwise return the empty string.

Sample Solution:

PHP Code :

<?php
// Define a function named 'test' that checks the prefix of a string
function test($s1)
{ 
    // Check if the first three characters of $s1 are "abc"
    if (substr($s1, 0, 3) == "abc")
    {
        // If true, return "abc"
        return "abc";
    }
    // Check if the first three characters of $s1 are "xyz"
    else if (substr($s1, 0, 3) == "xyz")
    {
        // If true, return "xyz"
        return "xyz";
    }
    // If the conditions are not met, return an empty string
    else
    {
        return "";
    }
}

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

Explanation:

Function Definition:

The function test is defined with one parameter:

$s1: the input string to check.

Prefix Check (First Condition):

The function checks if the first three characters of $s1 are "abc":

if (substr($s1, 0, 3) == "abc")

If true:

It returns the string "abc".

Prefix Check (Second Condition):

If the first condition is false, it checks if the first three characters of $s1 are "xyz":

else if (substr($s1, 0, 3) == "xyz")

If true:

It returns the string "xyz".

Default Return Value:

If neither condition is met:

It returns an empty string "".

Output:

abc
abc

xyz
xyz

Flowchart:

PHP Code Editor:

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