by Dinesh Thakur Category: File Handling

Let us define a structure student to store the HSC marks data of a student as follows:

struct student {

int seat no;

char name[60];

int marks(6];

} ;

We also define two functions: stud-read-data to read the examination data of a student from the keyboard and stud_print_data to print it to a text file. Their prototypes are given below.

int stud_read_data(struct student *stud);

void stud_print_data(FILE *fp, const struct student *stud);

Both functions have a parameter stud which is a pointer to struct student. This helps us avoid copying the entire student structure, which is quite large in size, when these functions are called. The stud_read_data function uses parameter stud to return to the calling function the data of a student entered from the keyboard. It also returns an integer as a function value to indicate the availability of data. As examination seat numbers are positive integer values, a zero or negative value can be entered as the seat number to indicate the end of data entry, in which case, the function returns 0. Otherwise, it returns 1 after reading the remaining data of a student.

To read the data of several students from the keyboard and write it to an output file associated with file pointer fp,we use a while loop as shown below.

while (stud_read_data(&stud))

stud_print_data(fp, &stud);

The complete program is given below in which the main function first opens marks.dat file in append mode using the fileopen. The append mode allows data to be added to an existing file. Then the student data is accepted from the keyboard using the stud_read_data function as long as it returns true, and it is written to the marks.dat file using the stud_print_data function. Finally the file is closed.

/* create HSC examination data for several students */

#include <stdio.h>

#include "fileopen.c"

struct student {

int seat no;

char name[60];

int marks(6];

} ;

int stud_read_data(struct student *stud);

void stud_print data(FILE *fp, const struct student *stud);

int main ()

{

   struct student stud;

   FILE *fp;

   fp = fileopen("marks.dat", "a","");/* open MARKS.DAT in append mode*/

    /* read student data and store it in file */

   while (stud_read_data(&stud))

   stud_print_data(fp, &stud);

   fclose (fp);

   return 0;

}

/* read HSC examination data of a student from keyboard */

int stud_read_data(struct student *stud)

{

   int i;

   printf("\nEnter HSC examination data for a student:\n");

   printf("Seat number: ");

   scanf ("%d", &stud->seat_no);

   if (stud->seat no <= 0)

       return 0; - /* indicates end of data entry */

       printf ("Student name: ");

       fflush (stdin);

       gets(stud->name);

       printf("Marks in six subjects: ");

       for (i = 0; i < 6; i++)

           scanf("%d", &stud->marks[i]);

           return l;

}

/* print HSC examination data of student to a text file */

void stud_print_data(FILE *fp, const struct student *stud)

{

    int i;

    fprintf(fp, "%d %s “,stud->seat_no, stud->name);

    for(i = 0; i < 6; i++)

    fprintf(fp, "%d ", stud->marks[i]);

    fprintf(fp, "\n");

}

The program is executed and the data of one student is first entered as shown below.

Enter HSC examination data for a student:

Seat number: 1

Student name: Dinesh Thakur

Marks in six subjects: 67 45 85 76 65 55

Enter HSC examination data for a student:

Seat number: .Q.

The program is executed again and the data of four more students is added. The contents of the marks.dat file are as shown below.

1 Dinesh Thakur 67 45 85 76 65 55

2 R. Kumar 67 65 54 45 43 34

3 Sandeep K. Aggarwal 80 87 89 90 98 99

4 Ms. Swati Sharma 37 45 56 67 87 64

5 Mr. Rohit Sharma 46 54 43 39 49 47



About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.