C program to read numbers from a file and store them in an array

C program to read numbers from a file and store them in an array:

In this post, we will learn how to read numbers from a text file and store them in an array in C. One text file is given and this file holds different number values. The C program will read all these values from that file and put them in an array. Also, the program will print the array contents.

Create the text file:

For this example, create one file testfile.txt and add the following content:

10
20
30
40
50

You can modify the content or change the name of the text file. But make sure to update the file name in the program below.

C Program to read numbers of a file and add them to an array:

The following C program will read the numbers from the above text file and put them in an array. You need to create one example.c file in the same folder with the text file testfile.txt to use the below code:

#include <stdio.h>

int main(void)
{
    int numbers[50];
    int i = 0;
    FILE *file;

    if (file = fopen("testfile.txt", "r"))
    {
        while (fscanf(file, "%d", &numbers[i]) != EOF)
        {
            i++;
        }
        fclose(file);

        numbers[i] = '\0';

        for (i = 0; numbers[i] != '\0'; i++)
            printf("%d\n", numbers[i]);
    }

    return 0;
}

Download it on Github

Here,

• The numbers variable is an array to hold the numbers.
• The file is the file pointer variable. This file pointer is used to hold the file reference once it is open.
• By using the fopen method, we are opening the file in read mode. The second parameter r is used for the read mode. If the file path is valid and if the file can be opened in read mode, it will run the code in the if block.
• The while loop reads the file content and puts the content i.e. the numbers in the numbers array. The i variable is used to point to the current location in the array. It starts from 0 and it is incremented by 1 on each iteration.
• Once the while loop ends, we are closing the file with the fclose method. Also, once the reading is completed, we are adding the NULL character \0 at the end of the array.
• The last for loop is used to print the contents of the numbers array, i.e. the numbers of the text file.

Output:

It will print the contents of the file, i.e. the numbers.

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