Reading multiple numbers from a text file in C

Question

What I want/need to accomplish is to read multipliable numbers within a text file.

I'm still a beginner to programming, and I'm unsure what to do.

Here's what my text file looks like:

23 35 93 55 37 85 99 6 86 2 3 21 30 9 0 89 63 53 86 79

Here's what my code looks like:

FILE* infile = fopen("Outputnum.txt", "r");

for(int i=0; i<20; i++){

    fscanf(infile, "%d", &outputnum);
    return outputnum;

}

Keep in mind I have this code within a function, as my main goal is to read each number in the text file and record the smallest, and second smallest numbers. (Which is only 20 numbers) I figured a for-loop would be the best way to approach this problem, but I'm only returning my first number within the text file. (I'm trying to avoid using array's as it crashes my terminal)

Comments are not for extended discussion; this conversation has been moved to chat. — Samuel Liew
– Samuel Liew, Commented Oct 23, 2020 at 1:04

hgs3 · Accepted Answer · 2020-10-22 23:02:31Z

2

It's better if you don't use a loop with a hardcoded number limit. In my solution I read the numbers until there aren't any numbers left. You'll also not want to use a return statement inside your loop as that will exit the current function.

#include <stdio.h>
#include <limits.h>

int main()
{
    int smallest = INT_MAX;
    int second_smallest = INT_MAX;
    int number;

    FILE *infile = fopen("numbers.txt", "r");
    if (infile)
    {
        while (fscanf(infile, "%d", &number) == 1)
        {
            if (number < smallest)
            {
                second_smallest = smallest;
                smallest = number;
            }
            else if (number < second_smallest)
            {
                second_smallest = number;
            }
        }
        fclose(infile);
    }

    printf("smallest: %d\n", smallest);
    printf("second smallest: %d\n", second_smallest);
    return 0;
}

edited Oct 22, 2020 at 23:02

answered Oct 22, 2020 at 21:31

hgs3

5754 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

David C. Rankin Over a year ago

Just a nit. After you open the file, check that the pointer isn't NULL. While your loop protects against attempting to read after a failed open, it complicates the placement of fclose(). If infile is validated after open, then you know fclose() is needed after the loop. Just relying on the loop to skip reading after a failed open relies of any open file to be closed after exit. Normally fine, but the OP mentions he want this in a function.

hgs3 Over a year ago

@DavidC.Rankin Good feedback, I updated the snippet to check for NULL and close the file.

Collectives™ on Stack Overflow

Reading multiple numbers from a text file in C

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related