Reading data from a file into an array - C language

Question

I have created a file data.txt which is to contain the data necessary for future calculations. I want to write a program that loads all of these data into an array. Here is my Minimal Example:

#include <stdio.h>
#include <strings.h>
#include <stdlib.h>

int main(void) {
    FILE *fp = fopen("data.txt", "r");
    int array[15];
    fread(array, sizeof(int), 15, fp);
    for(int i = 0; i < 15; i++) {
        printf("%d \n", array[i]);
    }
}

data.txt:

Output:

Could you tell me what can have gone wrong?

That is a text file, not a binary. Print your result in hex and you'll see it has read the characters. — Jongware
– Jongware, Commented Feb 11, 2018 at 20:24
fread reads a fixed size of data which does not suit a text file which has variable length data. I suggest you explore fgets and sscanf functions. — Weather Vane
– Weather Vane, Commented Feb 11, 2018 at 20:25
If you copy-paste your question title, verbatim, into the search box of your favorite search engine, I'm sure you will get thousands of duplicates here on stackoverflow.com. — Some programmer dude
– Some programmer dude, Commented Feb 11, 2018 at 20:25

Weather Vane · Accepted Answer · 2018-02-11 20:34:59Z

2

I suggest for a basic example to use fscanf. Later, it might be better to move on to using fgets and sscanf.

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    FILE *fp = fopen("data.txt", "r");
    if(fp == NULL) {
        exit(1);
    }
    int num;
    while(fscanf(fp, "%d", &num) == 1) {
        printf("%d\n", num);
    }
    fclose(fp);
    return 0;
}

Program output:

answered Feb 11, 2018 at 20:34

Weather Vane

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