Question

#include <stdio.h>

int main(){
    char *c="";
    printf("Input: ");
    scanf_s("%c", c);
    printf("%x", *c);
}

I want to input a few characters, and then output the entire string as a hexadecimal value. How do I do this?

Answer 1

You need a buffer, not a string constant, to read into. Also, never use any of the *scanf functions, and never use any of the *_s functions either.

The correct way to write your program is something like this:

int
main(void)
{
  char line[80];
  char *p;

  fputs("Input: ", stdout);
  fgets(line, sizeof line, stdin);

  for (p = line; *p; p++)
    printf("%02x", *p);

  putchar('\n');
  return 0;
}

… but I’m not sure exactly what you mean by “output the entire string as a hexadecimal value” so this may not be quite what you want.