C putc

putc() function is C library function, and it's used to write a character to the file. This function is used for writing a single character in a stream along with that it moves forward the indicator's position.

int putc( int c, FILE * stream );

int main (void)
{
  FILE * fileName;
  char ch;
  fileName = fopen("anything.txt","wt");
  for (ch = 'D' ; ch <= 'S' ; ch++) {
    putc (ch , fileName);
    }
  fclose (fileName);
  return 0;
}