Write a function named revString that accepts one character pointer as a parameter and returns no value. The parameter must be a C-string. This function must remove all of the digit character letters from the string. The revised string argument must be a valid C-string. Your function must not use any square brackets and must not use the strlen or strcpy library functions. The signature for revString should be: void revString( char * msg )

int main() { char msg[100] = "Happy 2021!"; revString(msg); cout << msg << endl; // prints: Happy ! }