Read till end of file into array

Question

I've been trying to figure where I'm going wrong but I can't seem to point out where my error is exactly.

I'm trying to read from my text file, these integers

5 2 4 9 10 1 8 13 12 6 3 7 11

into an array A. To make sure it works, I was trying to print A but only getting large random numbers instead. Can someone help me see where i'm going wrong please?

int main(){

FILE* in = fopen("input.txt","r");

int A[100];

while(!feof(in)){
    fscanf(in, "%s", &A);
    printf("%d", A)
  }

 fclose(in);
 return 0;
}

*this is just the main parts of the code related to the question

Please read [Why is “while ( !feof (file) )” always wrong?](http://stackoverflow.com/questions/5431941/why-is-while-feof-file-always-wrong). — Some programmer dude, Apr 19 '16 at 05:31
You need to read a [good book](http://stackoverflow.com/a/562377/3386109) about the basics of C programming. — user3386109, Apr 19 '16 at 05:32
As for your problem, you're printing the *address* of where the first element of `A` is stored (i.e. `&A[0]`). — Some programmer dude, Apr 19 '16 at 05:33
Maybe `int i = 0, A[100] = {0}; while (i < 100 && fscanf (in, " %d", &A[i]) == 1) {printf (" %d", A[i]; i++;}` ? — David C. Rankin, Apr 19 '16 at 05:41
Please format your code and fix the syntax errors. Right now your code cannot be compiled. — Jan Christoph Terasa, Apr 19 '16 at 05:48
Thank you David, that's EXACTLY what i was looking for. I couldn't remember how to format the while loop like this. It works perfect now — user3054901, Apr 19 '16 at 11:32

score 1 · Answer 1 · answered Apr 19 '16 at 05:55

For all those who actually read why using feof is always wrong, the solution is something similar to the following. The code will open the filename given as the first argument to the program (or read from stdin by default):

#include <stdio.h>

enum { MAXI = 100 };

int main (int argc, char **argv) {

    int i = 0, A[MAXI] = {0};   /* initialize variables */
    /* read from file specified as argument 1 (or stdin, default) */
    FILE *in = argc > 1 ? fopen (argv[1],"r") : stdin;

    if (!in) {  /* validate file opened for reading */
        fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
        return 1;
    }

    /* read each number from file or until array full */
    while (i < MAXI && fscanf (in, " %d", &A[i]) == 1)
        printf (" %d", A[i++]);
    putchar ('\n');

    if (in != stdin) fclose (in);

    printf ("\n '%d' numbers read from the file.\n\n", i);

    return 0;
}

Example Use/Output

Using your example values in the file dat/myints.txt results in the following:

$ ./bin/rdints dat/myints.txt
 5 2 4 9 10 1 8 13 12 6 3 7 11

 '13' numbers read from the file.

Read till end of file into array

1 Answers1