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cscanf

scanf in C doesn't fail when formatted text doesn't match

I have hard time understanding how scanf in C works. I need the code below to fail with the input 123 foo.

#include <stdio.h>

int main () {
  int i;
  if (scanf ("%d text", &i) != 1) {
      return 1;
  }
  return 0;
}

I found in C refs that scanf correctly returns the number of successfully assigned arguments (there's 1 specifier in my case), so I can see why the condition in the if statement is satisfied (the integer i is correctly assigned). However I can't see how I check whether the rest of the argument is satisfied as well (string text).

Solution

  • you need to do this manually.

    Example if you want to fail only if user inputs "123 foo"

    int main () 
{
  int i;
  char s[100];
  if (scanf ("%d %99s", &i, s) == 2 && !strcmp(s, "foo") && i == 123) 
  {
      return 1;
  }
  return 0;
}