Testing own functions to support string defined as char[] or char*
Must NOT use the <string> library
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1. myStrCopy: the whole string
a. in: source str
b. out: destination str
2. myStrCopy:
a. in: source str, start, end
b. out: destination str
3. myStrCompare
a. in: str1, str2
b. out: {-1, 0, 1} for {<, =, >}