Simple program unable to get toupper working

Question

Im practicing with the toupper function but i can make this work, always crash at the point of the printf so i think arguments are bad, or so.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main (void){

char pepito[10];

puts("\nTell me something: \n");
scanf("%9s", pepito);
puts("\a");
printf("Could be this?: %s", toupper(pepito[2]));

system("pause");    





}

`%s` is for strings, you want `%c` for individual characters. — Crowman, Aug 31 '14 at 23:50
`pepito[1]=toupper(pepito[1]);printf("Could be this?: %s\n", pepito);` — BLUEPIXY, Aug 31 '14 at 23:58
Arrays in C are `0` based. I.e. `pepito[0-9]` for the 10 characters, at most `0-8` usable for any character, the last must be the null-terminating character. So `pepito[1]` is the second char in the string. — David C. Rankin, Sep 01 '14 at 03:30

Elliott Frisch · Answer 1 · 2014-09-01T01:31:51.413

I'm not sure why you only call toupper() on the third char (and then tries to print the third char as a string - %s is not %c), I suspect that is actually your question - so your program should actually be using index 1 (indices start at 0),

int main (int argc, char *argv[]) {
  int i = 0;
  char pepito[10];

  puts ("\nTell me something: \n");
  scanf ("%9s", pepito);
  /* Capitalize the third letter. */
  pepito[1] = toupper (pepito[1]);
  /* print the capitalized pepito */
  printf ("Could be this?: %s\n", pepito);
}

Running it produces

$ ./a.out 

Tell me something: 

random
Could be this?: rAndom

Simple program unable to get toupper working

1 Answers1