计算机科学与技术

对下面程序描述正确的是(   )。 #include #include  void main()   {FILE *in,*out; if((in=fopen("file1.txt","a+"))==NULL)     {printf("cannot open file1\n");        exit(0);      }if((out=fopen("file2.txt","a+"))==NULL)  

对下面程序描述正确的是(   )。 #include #include  void main()   {FILE *in,*out; if((in=fopen("file1.txt","a+"))==NULL)     {printf("cannot open file1\n");        exit(0);      }if((out=fopen("file2.txt","a+"))==NU