fprintf() and fscanf() functions in C

fprintf() and fscanf() functions

            Most compilers support two functions namely fprintf() and fscanf() functions, that can handle a group of mixed data simultaneously.  The functions fprintf() and fscanf() perform I/O operations that are identical to printf() and scanf() functions, except that they work on files.

fscanf() funcnton:       fscanf() function is used to read mixed data simultaneously form a given file.  The general format of the fscanf() function is:

            Syntax:            fscanf(FilePointer, “ControlString”, List);

Where,

            FilePointer associated with the file that has been opened for reading.

            ControlString consists of format specification for the items in the list.

            List may include variables, constants, strings etc.,

Function returns EOF marker whenever end of the file has been reached.

fprintf() function:        fprintf() function is used to write mixed data simultaneously into a given file.  The general format of the fpritnf() function is:

            Syntax:            fprintf(FilePointer, “ControlString”, List);

Where,

            FilePointer associated with the file that has been opened for writing.

            ControlString consists of output format specification for the items in the list.

            List may include variables, constants, strings etc.,

           

/* WRITE A PROGRAM TO CREATE A FILE THAT CONTAINS INVENTORY DETAILS LIKE PRODUCT NUMBER, PRODUCT NAME AND PRODUCT COST.  READ THE SAME DATA FROM THE FILE AND PRINT IT */

#include<stdio.h>

#include<conio.h>

struct product

{

            int id;

            char name[20];

            float price;

}p;

main()

{

            char flag='y';

            FILE *f;

            clrscr();

            f=fopen("product.dat","w");

            while(flag=='y')

            {

               printf("\nEnter product id:");

               scanf("%d",&p.id);

               fflush(stdin);

               printf("\nEnter product name:");

               gets(p.name);

               printf("\nEnter product cost:");

               scanf("%f",&p.price);

               fprintf(f,"%d\t%s\t%f\n",p.id,p.name,p.price);

               printf("\nDo you want add another record(y/n):");

               fflush(stdin);

               flag=getchar();

            }

            fclose(f);

            f=fopen("product.dat","r");

            if(f==NULL)

            {

                        printf("\nFILE OPENING ERROR");

                        exit();

            }

            printf("\nPRODUCT DETAILS ARE:\n");

            while((fscanf(f,"%d%s%f",&p.id,p.name,&p.price))!=EOF)

            printf("\n%d\t%s\t%.2f",p.id,p.name,p.price);

            fclose(f);

}