二2.1 #include void main() { // 本题原考虑在 16 位机器上实验目前多为 32 位机器故已过时。int a = 42486; cout < #include const double pi = 3.1415926; void main() { double radius1, radius2; cout <<"please input two numbers:\n"; cin >>radius1 >>radius2; cout < #include const double e = 2.718281828; void main() { cout < void main() { cout <<"\"How many students here?\"\n" <<"\"500\"\n"; } 2.5 #include void main() { cout <<"size of char " <