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

A file is a collection of data stored in secondary memory. Files are used to store information that programs can determine. A file represents a sequence of bytes, Whether it is a text file or a binary file. It is a collection of records or is a location on the hard disk where data is stored permanently.

Operations on Files

The operations on files in the 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");

The putw() Function

The putw() function is used for writing a number into a file. This function writes binary data to a file. It requires two inputs: the data to be written and a pointer to the file. The syntax for putw() function is as follows ?

putw (int num, FILE *fp);

In the example below, the code writes the integer value to the file pointed to by the putw() function.

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

The getw() Function

The getw( ) function is used for reading a number from a file. The syntax for getw() function is as follows ?

int getw (FILE *fp);

Example

The below example reads an integer from the file that is pointed by fp and stores the data in the variable num using getw().

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
");
for (i =1; i<= 10; i++){
 i= getw(fp);
 printf ("%d",i);
 printf("
");
}
fclose (fp);

Example

Following is the C program to demonstrate the use of putw() and getw() functions. Here we store numbers from 1 to 10 and print them using these functions ?

#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
");
   for (i = 1; i <= 10; i++) {
      i = getw(fp);
      printf("%d", i);
      printf("
");
   }
 
   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