How to read multiple number from a text file

Question

So this is my code and I keep getting segmentation faults. How can I format this code to read a set of numbers from a file?

My input looks like this: 82, 46, 71, 56, 44, 12, 100 62, 67, 64, 65, 62, 39, 68 68, 90, 78, 57, 76, 45, 82 etc

#include <stdio.h>

int main ()
{
    FILE *input = fopen("input.txt", "r");

    int line[7];
    int store = 0, read;

    if(!input)
    {
        printf("Error: Filename \"input.txt\" not found!\n");
    }

    store = 0;
    while(fscanf(input, "%d", &read) != EOF)
    {            
        line[store] = read;                 
        store++;
    }

    printf("%d %d %d %d %d %d %d\n", line[0], line[1], line[2], line[3], line[4], line[5], line[6]); 
    return(0);
}

What's the file format? Check that store < 7 in your loop, and if input is NULL, not only print an error message, also exit(1). And if fscanf fails to read an int without getting an input error, its return value will be 0, so check fscanf(...) == 1. — Daniel Fischer
– Daniel Fischer, Commented Mar 20, 2013 at 23:50
There seems to be no guard in the for loop preventing you from overflowing line[]. What if there are more than 7 numbers in your file? — dotcomslashnet
– dotcomslashnet, Commented Mar 20, 2013 at 23:50
Okay thanks! My input looks like this: 82, 46, 71, 56, 44, 12, 100 62, 67, 64, 65, 62, 39, 68 68, 90, 78, 57, 76, 45, 82 etc. This help my case at all? (Also, if you know, how do I read the next line and so on?) — Josh Nash
– Josh Nash, Commented Mar 20, 2013 at 23:52
Oh, well there are lines of seven integers per line there but I don't know why I can't show it like that. — Josh Nash
– Josh Nash, Commented Mar 20, 2013 at 23:53
The commas are in the file? Then your fscanf will never manage to consume the first comma and return 0 until the programme segfaults because store is 1347 or whatever. — Daniel Fischer
– Daniel Fischer, Commented Mar 21, 2013 at 0:32

perreal · Accepted Answer · 2013-03-20 23:50:03Z

0

Change your while loop condition into:

while( store < sizeof(line)/sizeof(int) && fscanf(input, "%d", &read) != EOF)

looks like you have more numbers in the input then you have space for.

answered Mar 20, 2013 at 23:50

perreal

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1 Comment

Josh Nash Over a year ago

So this will prevent my line[] from overflowing?

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