Explain the functions putw() and getw() in C language

CServer Side ProgrammingProgramming

File is collection of records or is a place on hard disk, where data is stored permanently.

Operations on files

The operations on files in C programming language are as follows −

  • Naming the file
  • Opening the file
  • Reading from the file
  • Writing into the file
  • Closing the file

Syntax

The syntax for opening a file is as follows −

FILE *File pointer;

For example, FILE * fptr;

The syntax for naming a file is as follows −

File pointer = fopen ("File name", "mode");

For example,

fptr = fopen ("sample.txt", "r");
FILE *fp;
fp = fopen ("sample.txt", "w");

putw( ) and getw( ) functions

putw( ) function is used for writing a number into file.

The syntax for putw() function is as follows −

Syntax

putw (int num, FILE *fp);

For example,

Example

FILE *fp;
int num;
putw(num, fp);

getw( ) function is used for reading a number from a file.

The syntax for getw() function is as follows −

Syntax

int getw (FILE *fp);

For example,

Example

FILE *fp;
int num;
num = getw(fp);

The logic for writing numbers into a file is as follows −

fp = fopen ("num.txt", "w");
for (i =1; i<= 10; i++){
   putw (i, fp);
}
fclose (fp);

The logic for reading numbers from a file is as follows −

fp =fopen ("num.txt", "r");
printf ("file content is\n");
for (i =1; i<= 10; i++){
   i= getw(fp);
   printf ("%d",i);
   printf("\n");
}
fclose (fp);

Program

Following is the C program for storing the numbers from 1 to 10 and to print the same −

 Live Demo

#include<stdio.h>
int main( ){
   FILE *fp;
   int i;
   fp = fopen ("num.txt", "w");
   for (i =1; i<= 10; i++){
      putw (i, fp);
   }
   fclose (fp);
   fp =fopen ("num.txt", "r");
   printf ("file content is\n");
   for (i =1; i<= 10; i++){
      i= getw(fp);
      printf ("%d",i);
      printf("\n");
   }
   fclose (fp);
   return 0;
}

Output

When the above program is executed, it produces the following result −

file content is
1
2
3
4
5
6
7
8
9
10
raja
Published on 24-Mar-2021 13:37:51
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