Change_case
Write a program with 3 functions: (1) turn to uppercase (2) turn to lowercase (3) turn to wave string(uppercase->lowercase->uppercase->lowercase->...). Users will input a word and then choose which function to use. The length of the string will be less than 100000. Do not call toupper() and tolower() functions in this program (If you use these functions, you will get zero points).
Input Example
Output Example
challenge
1
CHALLENGE
TOBEORNOTTOBE
2
tobeornottobe
ProgramDesign
3
PrOgRaMdEsIgN
