copiar.c

#include <stdio.h>
#include <stdlib.h>

int main()
{
   char ch, source_file[20], target_file[20];
   FILE *source, *target;

   printf("NOME DO ARQUIVO A SER COPIADO\n");
   gets(source_file);

   source = fopen(source_file, "r");

   if (source == NULL)
   {
      printf("Press any key to exit...\n");
      exit(EXIT_FAILURE);
   }

   printf("NOME DA CÒPIA\n");
   gets(target_file);

   target = fopen(target_file, "w");

   if (target == NULL)
   {
      fclose(source);
      printf("Press any key to exit...\n");
      exit(EXIT_FAILURE);
   }

   while ((ch = fgetc(source)) != EOF)
      fputc(ch, target);

   printf("ARQUIVO COPIADO\n");

   fclose(source);
   fclose(target);

   return 0;
}