basic scanf question

blackzone · 07-15-2006, 03:51 PM

I read you can limit number of character get with %s by inserting a number(e.g. %5s").

But the below program still generate seg fault. Any comment?

Code:

#include <stdio.h>

int main()
{
  char myString[5];
  scanf("%5s", myString);

}

urzumph · 07-15-2006, 04:01 PM

I'm surprised that even compiles. scanf only takes pointers... you are giving it a char instead of a pointer to a char.

Edit : To little sleep, not enough reading before posting... myString is an array and therefore equivalent to a pointer

Also, I am reasonably sure that you need to make the array one char larger to allow for the NULL terminator.

xhi · 07-15-2006, 04:03 PM

you could use fgets...

char *fgets(char *s, int size, FILE *stream);

btw.. i dont know if there is a way to make scanf stop at a size..

randyding · 07-15-2006, 04:03 PM

First fgets() is better than scanf() for reading a line from stdin.
Second, you should be char mystring[6] to read a 5 char string, need room for the null terminator on the end.
Third, it should not segfault the way you have it because the compiler pads 5 bytes to 8 or 16 depending on architecture.