Concat two files using C

Question

How will write a C program which will concatenate two file and write it third file.

Comments

if we can use system command then its simple
main()
{
   system("cat file1 > file3");
   system("cat file2 >> file3");
}

Answer 1

void Cat(FILE *input_file, FILE *output_file)
{
   char ch;
   while( ( ch = fgetc(input_file) ) != EOF )
      fputc(ch,output_file);
}

int main ()
{
   FILE *input_file, *output_file;
   ...
   output_file = fopen(<filename 3>, "a+"); // Target file 
   input_file = fopen(<filename 1>, "r");
   Cat(input_file, output_file);
   fclose(input_file);

   input_file = fopen(<filename 2>, "r");
   Cat(input_file, output_file);
   fclose(input_file);
   fclose(output_file);
}