Error handling for multiple inputs at once

**sudozax** · 10-01-2015

Greetings, working on some basic code here.

Usually I run the following code to test input as non-integers or negatives, as most of my programs use positive integers.

Code:

while (scanf("%f", &input) != 1 ? scanf("%s") : 0 || input< 0)    {
        printf("Error! ");
        printf("Please enter input: ");
    }

However, I can't seem to apply that same principle to multiple inputs at once...

Code:

printf("Enter a date (mm/dd/yy): ");

while (scanf("%d/%d/%d", &m2, &d2, &y2) != 1 ? scanf("%s") : m2 < 0 || d2 < 0 || y2 < 0)
    {
        printf("Error! ");
        printf("Enter a date (mm/dd/yy): ");
    }

Does anyone know a good way to solve this problem?

The entire point of this program is to determine the earliest date out of however many dates the user inputs.

Full code here: [C] c06p10.c - Pastebin.com

**laserlight** · 10-01-2015

You forgot to change the number of expected assignments, i.e., scanf("%d/%d/%d", &m2, &d2, &y2) != 1 should be: scanf("%d/%d/%d", &m2, &d2, &y2) != 3

**sudozax** · 10-01-2015

Oh wow! Can't believe I missed that. Thank you!

**Salem** · 10-01-2015

> scanf("%s")
And where do you suppose this is going to write a string?
Or for that matter, what the return result is.

Try pressing ctrl-d (on Unix/Linux) or ctrl-z (dos/windows) when you're supposed to type something and see what happens.

Code:

char buff[BUFSIZ];
while ( fgets(buff,BUFSIZ,stdin) != NULL ) {
  if ( sscanf(buff,"%d/%d/%d", &m2, &d2, &y2) == 3 ) {
    // success
    break;
  } else {
    // error
  }
}

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