Incrementing C pointers

[qwe]

I am playing with some C programming and I wrote this simple program to print the arguments that were fed to the program.

#include <stdio.h>

int main(int argc, char * argv[]){
   char *pi;
   int i;
   pi = argv[1];
   printf("%d args.\n",argc-1);
   printf("input: ");
   for(i=0;i<argc-1;i++){
      printf("%c, ",*pi);
      /*The line below increments pi by 1 char worth of bytes */
      pi+=sizeof(pi)/2;
      /* An alternative to the above line is putting pi++ twice - why? */
   }
   printf("\n");
   return 0;
}

My question is that if I use the line pi++ shouldn't pi now point to the next char in the array? When I tried this it didn't work. I found that instead I had to increment pi twice for it to accurately put out the arguments as they were fed in.