toupper function using c++ code example

Example 1: c++ char to uppercase

char choice; 
// it will instantly transform it to upper case without the need
// to convert it to int first
choice = (char)toupper(choice);

Example 2: convert all characters in string to uppercase c++

transform(str.begin(), str.end(), str.begin(), ::toupper);

Example 3: c++ convert lowercase to uppercase

/* toupper example */
#include <stdio.h>
#include <ctype.h>
int main ()
{
  int i=0;
  char str[]="Test String.\n";
  char c;
  while (str[i])
  {
    c=str[i];
    putchar (toupper(c));
    i++;
  }
  return 0;
}