File Handling in C: Important Questions and Programs for Exams (2026)

File Handling in C (Important for Exams)

File handling in C is used to store data permanently in files instead of temporary memory.

Without file handling, all data is lost when the program ends. That’s why it is an important concept for both exams and real-world programs.

In C, we use a FILE pointer and functions like:

• fopen()
• fclose()
• fprintf()
• fscanf()
• fgetc() / fputc()

Opening and Closing a File

A file is opened using fopen() and closed using fclose().

FILE fp;
fp = fopen("test.txt", "w");
fclose(fp);

#include <stdio.h>

int main() {
    FILE fp;

    fp = fopen("test.txt", "w");

    if(fp == NULL) {
        printf("File not opened");
        return 0;
    }

    fprintf(fp, "Hello World");

    fclose(fp);
    return 0;
}

Important Program 2: Read Data from File

This program reads data from an existing file.

#include <stdio.h>

int main() {
    FILE fp;
    char ch;

    fp = fopen("test.txt", "r");

    if(fp == NULL) {
        printf("File not found");
        return 0;
    }

    while((ch = fgetc(fp)) != EOF) {
        printf("%c", ch);
    }

    fclose(fp);
    return 0;
}

#include <stdio.h>

int main() {
    FILE fp1, fp2;
    char ch;

    fp1 = fopen("source.txt", "r");
    fp2 = fopen("dest.txt", "w");

    if(fp1 == NULL || fp2 == NULL) {
        printf("File error");
        return 0;
    }

    while((ch = fgetc(fp1)) != EOF) {
        fputc(ch, fp2);
    }

    fclose(fp1);
    fclose(fp2);
    return 0;
}

#include <stdio.h>

int main() {
    FILE fp;

    fp = fopen("test.txt", "a");

    fprintf(fp, "\nNew Data Added");

    fclose(fp);
    return 0;
}

File Modes (Must Remember)

Important Viva Questions

• What is FILE pointer?
• What is EOF?
• Difference between fprintf and fputc?
• What happens if file does not exist?
• Difference between text and binary file?

Common Mistakes

• Forgetting fclose()
• Not checking NULL pointer
• Using wrong file mode
• Incorrect file path

Final Tip

Focus on understanding 3–4 programs properly. Most exam questions are based on these patterns only.