C Program to Write ODD, and EVEN Numbers Integer Data Files

To Write C program that would print ODD and EVEN numbers handling Integer Data files. The C program to give step by step simple example.The file named DATA contains series of integer numbers. Code a program to read these numbers and then write all ‘odd’ numbers to a file to be called ODD and all `even’ numbers to a file to be called EVEN.

The program is shown below example. It uses three files simultaneously and therefore we need to define three-file pointers f1, f2 and f3.

First, the file DATA containing integer values is created. The integer values are read from the terminal and are written to the file DATA with the help of the statement putw(number, f1);

Notice that when we type -1, the reading is terminated and the file is closed. The next step is to open all the three files, DATA for reading, ODD and EVEN for writing. The contents of DATA file are read, integer by integer, by the function getw(f1) and written to ODD or EVEN file after an appropriate test. Note that the statement

(number = getw(f1)) != EOF

reads a value, assigns the same to number, and then tests for the end-of-file mark.

Finally, the program displays the contents of ODD and EVEN files. It is important to note that the files ODD and EVEN opened for writing are closed before they are reopened for reading.

Example : C Program to Write ODD and EVEN Numbers

#include <stdio.h>
main()
{
   FILE *f1, *f2, *f3;
   int number, i;
   printf("Contents of DATA file\n\n");
   f1 = fopen("DATA", "w"); /* Create DATA file */
   for(i = 1; i <= 30; i++)
   {
      scanf("%d", &number);
      if(number == -1) break;
      putw(number,f1);
   }
fclose(f1);

f1 = fopen("DATA", "r");
f2 = fopen("ODD", "w");
f3 = fopen("EVEN", "w");

/* Read from DATA file */
while((number = getw(f1)) != EOF)
{
    if(number %2 == 0)
       putw(number, f3); /* Write to EVEN file */
    else
       putw(number, f2); /* Write to ODD file */
}
fclose(f1);
fclose(f2);
fclose(f3);

f2 = fopen("ODD","r");
f3 = fopen("EVEN", "r");
printf("\n\nContents of ODD file\n\n");

while((number = getw(f2)) != EOF)
     printf("%4d", number);
printf("\n\nContents of EVEN file\n\n");

while((number = getw(f3)) != EOF)
     printf("%4d", number);
fclose(f2);
fclose(f3);
}

Output

Contents of DATA file
111 222 333 444 555 666 777 888 999 000 121 232 343 454 565 -1
Contents of ODD file
111 333 555 777 999 121 343 565
Contents of EVEN file
222 444 666 888 0 232 454

Let me know if you find any difficulty in understanding this C Program write ODD and EVEN numbers handling Integer Data files. example and I would be glad to explain it further.