PHP program to reverse a string without predefined function

In this article, you will learn how to reverse a sting without predefined function. There is a predefined method strrev(), which can easily be used to revere a string, but we should also know the logic. Logic in programming is a fundamental key to be a decent developer. Possibly, depending on your employment place you are going to use more algorithms or not. If you are a front-end developer possibly somewhat more and if you are a back-end developer substantially more, you need to deal with complex algorithms. Here, we have mentioned two ways to reverse a string.

Method1 : PHP reverse string using strlen and for loop

In the given example, first we are getting the length of the string using strlen() function and then we iterate through it using for loop and print the string in reverse order -

<?php

// consider string
$string = 'Welcome to ETUTORIALSPOINT';
 
echo "Entered String: " . $string . "<br />"; 
// find string length
$str_len 	= strlen($string);

echo "Reversed String: "; 

// loop through it and print it turn around
for ( $x = $str_len - 1; $x >=0; $x-- )
{
  echo $string[$x];
}
?>

Entered String: Welcome to ETUTORIALSPOINT
Reversed String: TNIOPSLAIROTUTE ot emocleW

Method2 : PHP Revere string using while and for loop

In the given example, we are reversing the given string using while and for loop -

<?php

// Consider a string
$string = 'Welcome to ETUTORIALSPOINT';
 
// Print Input String
echo "Given String: " . $string . "<br />";
 
// Print Reversed String
echo "Reversed String: ";
echo reverse_str($string);
 
// Function to reverse a string
function reverse_str($string)
{
    $x = 0;
    $reverse_str = "";
    while($string[$x]) {
        $x++;
    }
    for ($y = $x - 1; $y >= 0; $y--) {
        $reverse_str .= $string[$y];
    }
    return $reverse_str;
}
?>

Given String: Welcome to ETUTORIALSPOINT
Reversed String: TNIOPSLAIROTUTE ot emocleW

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