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($resStr);   ?> |
Output:
GOING BACK HE SAW THIS 123$#%
