scanf string in c - why can i scan more than the char[] declaration?

Question

I have a program where I need to scanf a string, which I know it will be only 2 characters long. (for example: \"ex\"). what is the proper way to do that?

I was goin

Answer 1

but when I enter a 10-letter word it also works just fine. How come? Does the [3] has no meaning?

I doesn't work fine. See in this example:

#include 

int
main(int argc, char **argv)
{
  char second[5] = "BBBB";
  char myStr[3] = {0};

  scanf("%s", myStr);

  printf("second = %s\n", second);
  printf("myStr  = %s\n", myStr);

  return 0;
}

writing only two characters in myStr is fine:

a.exe
AA
second = BBBB
myStr  = AA

writing more data overrides the near by memory of second:

a.exe
AAAAAAA
second = AAAA
myStr  = AAAAAAA

You need to limit the number of characters scanf reads using something like scanf("%2s", myStr);, 2 is the size of myStr - 1.