C fputc() function

Last update on September 20 2022 12:34:20 (UTC/GMT +8 hours)

C library function - fputc()

The fputc() function is used to write the byte specified by c to the output stream pointed to by stream, at the position indicated by the associated file-position indicator for the stream (if defined), and shall advance the indicator appropriately.

Syntax:

int fputc(int c, FILE *stream)

Parameters:

Name	Description	Required /Optional
c	This is the character to be written. This is passed as its int promotion.	Required
stream	Identifies an address for a file descriptor, which is an area of memory associated with an input or output stream.	Required

Return value

Upon successful completion, fputc() shall return the value it has written.
Otherwise, it shall return EOF, the error indicator for the stream shall be set, and errno shall be set to indicate the error.

Example: fputc() function

#include <stdio.h>
int main () {
   FILE *fp;
   int ch;
   char string[100];
   
   fp = fopen("test.txt", "w+");
   for( ch = 65 ; ch <= 122; ch++ ) {
      fputc(ch, fp);
   }
   fclose(fp);
   fp=fopen("test.txt","r");
   fgets(string,100,fp);
   printf("The string is:\n%s",string);
   fclose(fp); 
   return 0;
}

Output:

The string is:
ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz

Example: Write the contents of buffer to a file

#include <stdio.h>
 
#define ALPHA  6
 
int main(void)
{
  FILE * fp;
  int i;
  int ch;
  char string[6];
 
  char buffer[ALPHA + 1] = "aeiou";
 
  if (( fp = fopen("test.txt", "w"))!= NULL )
  {
    /* Put buffer into file */
    for ( i = 0; ( i < sizeof(buffer) ) &&
           ((ch = fputc( buffer[i], fp)) != EOF ); ++i );
    fclose(fp);
  }
  else
   perror( "Error opening test.txt" );
   fp=fopen("test.txt","r");
   fgets(string,6,fp);
   printf("The string is: %s",string);
   fclose(fp); 
   return 0;
}

Output:

The string is: aeiou

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