Pass a string to a function: Invert the case of the letters within a string : function parameters « Function « C++ Tutorial

1. C++ Tutorial
2. Function
3. function parameters

#include <iostream> 
#include <cstring> 
#include <cctype>  
using namespace std; 
 
void f(char *str); 
 
int main() 
{ 
  char str[80]; 
 
  strcpy(str, "ABCD"); 
 
  f(str); 
 
  cout << str; 
  return 0; 
} 
 
 
void f(char *str) 
{ 
  while(*str) { 
    if(isupper(*str)) 
        *str = tolower(*str);  
    else if(islower(*str)) 
        *str = toupper(*str); 
    str++; 
  } 
}

abcd