Syntax problem with a predefined function

[LP18Aug0022 (Jai Chaudhry)]

whats the syntax of tolower and to upper functions
i am not able to find this on net

[Abhishek-Vanjani-1385688111468238 (Abhishek Vanjani)]

https://ide.codingblocks.com/#/s/30690

i have added the syntax along with comments and explanations.