二2.1#includevoidmain(){//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。inta=42486;cout<#includeconstdoublepi=3.1415926;voidmain(){doubleradius1,radius2;cout<<"pleaseinputtwonumbers:\n";cin>>radius1>>radius2;cout<#includeconstdoublee=2.718281828;voidmain(){cout<voidmain(){cout<<"\"Howmanystudentshere?\"\n"<<"\"500\"\n";}2.5#includevoidmain(){cout<<"sizeofchar"<#include#include#includevoidmain(){floata,b,c,s,area;//printf("pleaseinput3sidesofonetriangle:\n");cout<<"pleaseinput3sidesofonetriangle:\n";//scanf("%f,%f,%f",&a,&b,&c);//输入时以逗号作为数据间隔cin>>a>>b>>c;//输入时以空格作为数据间隔s=(a+b+c)/2;area=sqrt(s*(s-a)*(s-b)*(s-c));//printf("a=%7.2f,b=%7.2f,c=%7.2f\n",a,b,c);cout<#include#includefloatarea(floata,floatb,floatc);//函数声明voidmain(){floata,b,c;cout<<"pleaseinput3sidesofonetriangle:\n";cin>>a>>b>>c;//输入时以空格作为数据间隔floatresult=area(a,b,c);//函数调用cout<#includedoubleCylinder(doubler,doubleh);voidmain(){doubleradius,height;cout<<"请输入圆柱体的半径和高:\n";cin>>radius>>height;doublevolume=Cylinder(radius,height);cout<<"该圆柱体的体积为"<voidmain(){intx;cout<<"pleaseinputx:\n";cin>>x;if(x<=-1)cout<<(x-1)<-1&&x<=2)cout<...