From w3schools.com, Experiment by Teeratus_R
The strtoupper() function returns the string in upper case:
HELLO WORLD!The strtolower() function returns the string in lower case:
hello world!The str_replace() function replaces some characters with some other characters in a string.
Hello Dolly!The PHP strrev() function reverses a string.
!dlroW olleHWhitespace is the space before and/or after the actual text, and very often you want to remove this space.
Hello World!