file I/O operations

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);
}