C Programming File Examples

In this article, you'll find several examples that will help you learn how to handle file input/output operations in C.

To understand all programs in this article, you should have the knowledge of the following topics:

1. Arrays
2. Pointers
3. Array and Pointer Relation
4. Standard Library Functions
5. File I/O

C Programming File examples

Read name and marks of students and store it in file

Read name and marks of students and store it in file. If file already exists, add information to it.

Write members of arrays to a file using fwrite()

1. Write a C program to read name and marks of n number of students from user and store them in a file.

#include <stdio.h>
int main()
{
   char name[50];
   int marks, i, num;

   printf("Enter number of students: ");
   scanf("%d", &num);

   FILE *fptr;
   fptr = (fopen("C:\\student.txt", "w"));
   if(fptr == NULL)
   {
       printf("Error!");
       exit(1);
   }

   for(i = 0; i < num; ++i)
   {
      printf("For student%d\nEnter name: ", i+1);
      scanf("%s", name);

      printf("Enter marks: ");
      scanf("%d", &marks);

      fprintf(fptr,"\nName: %s \nMarks=%d \n", name, marks);
   }

   fclose(fptr);
   return 0;
}

2. Write a C program to read name and marks of n number of students from user and store them in a file. If the file previously exits, add the information of n students.

#include <stdio.h>
int main()
{
   char name[50];
   int marks, i, num;

   printf("Enter number of students: ");
   scanf("%d", &num);

   FILE *fptr;
   fptr = (fopen("C:\\student.txt", "a"));
   if(fptr == NULL)
   {
       printf("Error!");
       exit(1);
   }

   for(i = 0; i < num; ++i)
   {
      printf("For student%d\nEnter name: ", i+1);
      scanf("%s", name);

      printf("Enter marks: ");
      scanf("%d", &marks);

      fprintf(fptr,"\nName: %s \nMarks=%d \n", name, marks);
   }

   fclose(fptr);
   return 0;
}

3. Write a C program to write all the members of an array of structures to a file using fwrite(). Read the array from the file and display on the screen.

#include <stdio.h>
struct student
{
   char name[50];
   int height;
};
int main(){
    struct student stud1[5], stud2[5];   
    FILE *fptr;
    int i;

    fptr = fopen("file.txt","wb");
    for(i = 0; i < 5; ++i)
    {
        fflush(stdin);
        printf("Enter name: ");
        gets(stud1[i].name);

        printf("Enter height: "); 
        scanf("%d", &stud1[i].height); 
    }

    fwrite(stud1, sizeof(stud1), 1, fptr);
    fclose(fptr);

    fptr = fopen("file.txt", "rb");
    fread(stud2, sizeof(stud2), 1, fptr);
    for(i = 0; i < 5; ++i)
    {
        printf("Name: %s\nHeight: %d", stud2[i].name, stud2[i].height);
    }
    fclose(fptr);
}