PHP strtoupper() Function

The strtoupper() function is used to convert a string into uppercase. This function takes a string as parameter and converts all the lowercase english alphabets present in the string to uppercase. All other numeric characters or special characters in the string remains unchanged.

Syntax:

string strtoupper ( $string )

Parameter: The only parameter to this function is a string that is to be converted to upper case.

Return value: This function returns a string in which all the alphabets are uppercase.

Examples:

Input : $str  = "GeeksForGeeks"
        strtoupper($str)
Output: GEEKSFORGEEKS

Input : $str  = "going BACK he SAW THIS 123$#%"
        strtoupper($str)
Output: GOING BACK HE SAW THIS 123$#%

Below programs illustrate the strtoupper() function in PHP:

Program 1

<?php

// original string
$str = "GeeksForGeeks";

// string converted to upper case
$resStr = strtoupper($str);

print_r($resStr);

?>

Output:

GEEKSFORGEEKS

Program 2

<?php

// original string
$str = "going BACK he SAW THIS 123$#%";

// string to upper case
$resStr = strtoupper($str);

print_r($resStr);

?>

Output:

GOING BACK HE SAW THIS 123$#%

Reference:
http://php.net/manual/en/function.strtoupper.php