阅读以下程序及对程序功能的描述,其中正确的描述是 ( ) # include int main( ) { FILE * in , * out ; char ch , infile[10] , outfile[10] ; printf("Enter the infile name :\ n") ; scanf("%s" , infile) ; printf("Enter the outfile name :\ n ") ; scanf("%s" , outfile) ; if((in=fopen(infile , "r"))= =NULL) { printf("Cannot open infile! \n") ; exit(0) ; } if((out=fopen(outfile , "w"))= =NULL) { printf("Cannot open outfile!\n") ; exit(0) ; } while(! feof(in)) fputc(fgetc(in) , out) ; fclose(in) ; tclose(out) ; return 0 ; }