File Input Output Example in C

About this page

This is a hands-on example program in C Other Programs — write student records to a file, then read them back. It applies the concepts from the file-handling tutorials in one complete program.

Introduction

This program demonstrates reading from and writing to a text file using standard C file functions from <stdio.h>.

File I/O Functions Used

Function	Purpose
fopen(path, mode)	Open a file ("w", "r", "a")
fprintf(file, ...)	Formatted write to file
fscanf(file, ...)	Formatted read from file
fclose(file)	Close file and flush buffers

Write and Read Example Program

#include <stdio.h>

int main(void) {
    FILE *fp;
    int num;
    char name[50];

    /* Write to file */
    fp = fopen("student.txt", "w");
    if (fp == NULL) {
        printf("Error opening file for writing\n");
        return 1;
    }
    fprintf(fp, "%d %s\n", 101, "Arun");
    fprintf(fp, "%d %s\n", 102, "Meera");
    fclose(fp);

    /* Read from file */
    fp = fopen("student.txt", "r");
    if (fp == NULL) {
        printf("Error opening file for reading\n");
        return 1;
    }

    printf("ID   Name\n");
    printf("---- ------\n");
    while (fscanf(fp, "%d %49s", &num, name) == 2)
        printf("%-4d %s\n", num, name);

    fclose(fp);
    return 0;
}

Sample Output

ID   Name
---- ------
101  Arun
102  Meera

A file named student.txt is created in the working directory with the same data.

File Open Modes

Mode	Meaning
"r"	Read (file must exist)
"w"	Write (creates or overwrites)
"a"	Append (creates if missing)
"r+"	Read and write

Error Handling

Always check that fopen returns non-NULL before using the file pointer. Always call fclose when done.

Learn More

For a complete guide see File Handling in C Programming.

Related Pages

Learn the concept first, then study the code:

• C Programs — Browse all C Programs.
• If Else Statement in C — Tutorial — decision control for utility programs.
• Reverse Number Example Program In C Programming Language — More in c other programs.
• Example Program for Print 1 to N In C Programming — More in c other programs.