74.Input and output of c language : Binary file, fread(), fputs()

 Binary files:

 

Text file is a file where the data of any type is converted into text and stored.

For example the salary 7560 will be converted into individual characters and stored as individual characters "7", "5", "'6" and "0".

When we read into the program then the text type is again converted into number type.

It takes more memory (7560 takes 2 bytes where as "7560" takes 4 bytes because every character takes 1 byte)

It shows less performance in writing and reading from the file (Because data must be converted while writing and reading from the file)

 

 

   

 

 

 

 

 

 

 

 

We can save the memory and improve the performance by writing the binary data directly on to the file.

The file with binary data is called a binary file.

Binary files can't open with any other applications.

 

fwrite():

It is a function used to write an object (structure variable) on to the file in a binary format

Writes "n" items of "size" bytes each through the file pointer

It accepts the address of object, size of object, number object to be written and the file pointer as arguments.

Returns the number of actually written items (not bytes)

 

Function definition:

 

                    int fwrite(void *ptr, int size, int n, FILE *fp);

                    {

                           -------------------------------------

                           -------------------------------------

                           -------------------------------------

                    }

Example:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Example explained:

1. Creating the file "data1" in binary write mode.
2. fwrite() is used to write the object on to the file in a binary format. Here the address of object (6332), size of object (44), number of objects (1) and the file pointer are sending as arguments.

 

fread():

It is the function used to read the binary data from the file and store into the object

Reads "n" items of "size" bytes each through the file pointer

It accepts the address of object, size of object, number object to be read and the file pointer as arguments.

Returns the number of items fetched from the file (not bytes)

 

Function definition:

 

                    int fread(void *ptr, int size, int n, FILE *fp);

                    {

                           -------------------------------------

                           -------------------------------------

                           -------------------------------------

                    }

Example:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Program explained:

1. Opening the file "data1" in binary read mode
2. fread() is used to read the binary data from the file and write onto the object. Here the address of object (6332), size of object (44), number of objects (1) and the file pointer are sending as arguments.

 

Specification7:

Accept "n" addresses from the keyboard and write onto the file "data1"

 

Program:

#include<stdio.h>

struct address

{

   char name[20];

   char place[20];

   long int pin;

};

void main()

{

   FILE *p;

   struct address x;

   int n,i;

   clrscr();

   p=fopen("data1","wb");

   printf("How many records?");

   scanf("%d",&n);

   printf("Enter %d records:\n",n);

   for(i=1;i<=n;i++)

   {

      printf("Name:");

      scanf("%s",x.name);

      printf("Place:");

      scanf("%s",x.place);

      printf("Pin code:");

      scanf("%ld",&x.pin);

      fwrite(&x,sizeof(x),1,p);

   }

   fclose(p);

   printf("1 file created");

   getch();

}

 

Execution:

How many records?3

Enter 3 records:

 

Name:Smith

Place:Kavali

Pin code:524201

 

Name:John

Place:RudraKota

Pin code:524201

 

Name:Black

Place:BudamGunta

Pin code:425201

 

1 file created

 

Specification8:

Read the data from file "data1" and display onto the monitor.

 

Program:

#include<stdio.h>

struct address

{

   char name[20];

   char place[20];

   long int pin;

};

void main()

{

   FILE *p;

   struct address x;

   clrscr();

   p=fopen("data1","rb");

   printf("Rcords of file:\n");

   while(1)

   {

     fread(&x,sizeof(x),1,p);

     if(feof(p)!=0)

       break;

     printf("\n\nName:%s\nPlace:%s\nPin code:%ld",x.name,x.place,x.pin);

   }

   fclose(p);

   getch();

}

 

 

 

Execution:

Rcords of file:

 

Name:Smith

Place:Kavali

Pin code:524201

 

Name:John

Place:RudraKota

Pin code:524201

 

Name:Black

Place:BudamGunta

Pin code:425201

1 file created

 

fputs():

It is the function used to print a string onto the file.

It accepts both the string and the file pointer as arguments.

It returns the last character written on to the file if operation is successful otherwise returns -1 

 

Function definition:

         int fputs(char *s, FILE *p)

         {

                 -------------------------

                 -------------------------

                 -------------------------

          }

 

Specification9:

Accept multiple lines of text and write onto the file "fruits".

 

Program:

#include<stdio.h>

#include<string.h>

void main()

{

   FILE *p;

   char x[40];

   clrscr();

   p=fopen("fruits","w");

   printf("Enter the names of fruits:\n");

   printf("exit to close..\n");

   while(1)

   {

      gets(x);

      strcat(x,"\n");

      if(strcmp(x,"exit")==0)

             break;

      fputs(x,p);

   }

   fclose(p);

   printf("1 file created");

   getch();

}

 

Execution:

Enter the names of fruits:

exit to close..

apple

Goa

grapes

jackfruit

exit

 

Note: Here "exit" is used as terminating word but not written on the file.

 

Program explained:

Opened the file "fruits" in write mode

gets() is used to read a line of text from the keyboard

Writing the strings on to the file using fputs() through the file pointer

strsmp(x,"exit") is used to check for end of file