c++

Write a program that initializes an array of characters with the phrase, Take me to Clearwater Beach!. Using pointers, scan the array to make each character upper case. The catch: you may NOT use the isupper(), islower(), toupper(), or tolower() functions. You must calculate whether a character is upper or lower case, and use the same logic to convert to upper case where applicable.

Hints:

*cptr >= a && *cptr <= z

Assuming the ASCII value for a is greater than A, how could you use an expression like, (a A) to convert to upper case?