填空题下列程序的主要功能是()。 #include 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); fclose(out); }