How to Read Text file in C

Hello everyone, in this article we are going to see how can we read a file until the end and assign line by line to a variaable in C programming language with an example.

Let's get started.

First we are going to need below libraries. So include them:


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

Now rest of codes are will be in int main( void ) { ... } function.

First we request from user to specify the file


    char filePath[100];
    printf( "Enter file or drag file here to get file path :");
    gets( filePath );

Then we load inputted file path to the FILE structure to read
also we need a variable to read the text line by line
Also we can count how many lines do we have in text file


char const* const fileName = filePath; 
FILE* file = fopen(fileName, "r");

char line[1000];

char c;
int lineCount = 0;

Now we check the text file is correct and count the newlines


    for (c = getc(file); c != EOF; c = getc(file))
            if (c == '\n')
                lineCount++;

Here we clear the related pointer and reload the file


    fclose(file);
    file = fopen(fileName, "r");

Here you can make some controls on the characters EOF = end of file, You can make this control with different ways you can use ASCII encoding or whatever you want


for (c = getc(file); c != EOF; c = getc(file)){
       if (!(c == '0' || c == '1' || c == '2'   c == 'a' || c == 'b' || c == 'c' ||c == '\n')){
           return 0;
       }
}

Again we clear the related pointer and reload the file.


    fclose(file);
    file = fopen(fileName, "r");

Lastly we print all text line by line and close the file when operation is completed


    int i = 0;
    while (fgets(line, sizeof(line), file)) {
        i++;
        printf("Line %d : %s", i, line);
    }
   printf("\n");
    fclose(file);

I have commented the control section to show you that the example is working. Do not forget there when you are in need.

Below image you can see the example output:

That is all in this article.

You can reach the example code file on Github : https://github.com/thecodeprogram/TheSingleFiles/blob/master/reading_text_file_in_c.c

Burak Hamdi TUFAN.

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Author

Burak Hamdi TUFAN

I am a software developer experienced 15 years and here to share all my programming experiences. I have worked on so many platforms and programming languages especially C, C#, C++ and Java. I am studing PhD at Kocaeli University on Aviation Technologies. I am building softwares and technologies on aviation.

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