(Program in C++) Using only pointer notation, implement and test the following functions that operate on strings: int strCmp ( const char *s1, const char *s2) returns 0 if s1 and s2 are the same; it returns-1 when s1 precedes alphanumerically s2 or it returns 1 when s1 follows alphanumerically s2. char * strPbrk (const char*s1, const char*s2) scans s1 for the first occurrence of any character appearing in s2 and returns a pointer to its location or NULL if no such occurrence is found. char* ItoA ( int n, char*s) converts an integer n into string of numerals stored in s and returns s.