How to print content to a file using C language?

We can write a program in C that prints some content to a file and prints the following -

• The characters entered into the file number.
• Reverse characters entered into the file.

First, try to store a certain number of characters into the file by opening the file in write mode.

For inputting data into a file, we use the following logic -

while ((ch = getchar( ))!=EOF) {//after enter data press cntrl+Z to terminate
   fputc(ch, fp);
}

With the help of ftell, rewind, and fseek functions, we can reverse the content that has been input into the file.

Example

The following is a C program for printing to write some content to a file and print the number of characters and reverse the characters entered into the file -

Live Demonstration

#include<stdio.h>
int main( ){
   FILE *fp;
   char ch;
   int n,i=0;
   fp = fopen ("reverse.txt", "w");
   printf ("enter text press ctrl+z of the end");
   while ((ch = getchar( ))!=EOF){
      fputc(ch, fp);
   }
   n = ftell(fp);
   printf ( "No. of characters entered = %d</p><p>", n);
   rewind (fp);
   n = ftell (fp);
   printf ("fp value after rewind = %d</p><p>",n);
   fclose (fp);
   fp = fopen ("reverse.txt", "r");
   fseek(fp,0,SEEK_END);
   n = ftell(fp);
   printf ("reversed content is</p><p>");
   while(i<n){
      i++;
      fseek(fp,-i,SEEK_END);
      printf("%c",fgetc(fp));
   }
   fclose (fp);
   return 0;
}

Output

When the above program is executed, the following results are produced-

enter text press ctrl+z of the end
TutorialsPoint
^Z
No. of characters entered = 18
fp value after rewind = 0
reversed content is
tnioPslairotuT

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