2-28
if-else语句
#include <iostream> using namespace std; int main() { char x; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one: "<<endl; cin>>x; while(x!='Q') { if(x=='A') { cout<<"Data has added!"<<endl; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one:"; cin>>x;continue; } else if(x=='D') { cout<<"Data has deleted!"<<endl; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one:"; cin>>x;continue; } else if(x=='S') { cout<<"Data has sorted!"<<endl; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one:"; cin>>x;continue; } else { cout<<"Error!"<<endl; cout<<"Please select again!"<<endl; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one:"; cin>>x; } if(x=='Q') break; } return 0; }
switch语句
#include<iostream> using namespace std; int main() { char select; int x=1; cout<<"Menu:A(dd) D(elete) S(ort) Q(uit),Select one:"<<endl; while(x) { cin>>select; switch(select){ case 'A':cout<<"Data has added!"<<endl;continue; case 'D':cout<<"Data has deleted!"<<endl;continue; case 'S':cout<<"Data has sorted!"<<endl;continue; case 'Q':i=0;break; default:cout<<"Error!"<<endl; cout<<"Please select again!"<<endl; cout<<"Menu: A(dd) D(elete) S(ort) Q(uit),Select one:"; } } return 0; }
2-29
while语句
#include<iostream>
using namespace std;
int main()
{
int i=1,j;
while(i<=100)
{
for(j=2;j<i;j++){
if(i%j==0)break;
}
if(i==j)
cout<<i<<" ";
i++ ;
}
}
do while语句
#include<iostream> using namespace std; int main() { int i=1,j; do{ for(j=2;j<i;j++) {if(i%j==0) break; } if(i==j) cout<<i<<" "; i++ ; }while(i<=100); }
for语句
#include<iostream> using namespace std; int main() { int i,j; for(i=1;i<=100;i++){ for(j=2;j<i;j++){ if(i%j==0) break; } if(i==j) cout<<i<<" "; } }
2-32
while语句
#include<iostream>
using namespace std;
int main() {
int i=88;
int j;
while(1){
cout<<"猜一个数(范围1-100)"<<endl;
cin>>j;
if(j<i)
cout<<"猜小了!"<<endl;
else if(j>i)
cout<<"猜大了!"<<endl;
else
{
cout<<"猜对了!"<<endl;
break;}
}
return 0;
}
do while语句
#include<iostream> using namespace std; int main() { int i=88; int j; do{ cout<<"猜一个数(范围1-100)"<<endl; cin>>j; if(j<i) cout<<"猜小了"<<endl; else if(j>i) cout<<"猜大了"<<endl; else { cout<<"猜对了!"<<endl; break;} }while(1); return 0; }
2-34
#include <iostream> using namespace std; int main() { int i,j,k,x=0; for(i=1;i<=5;i++) for(j=i+1;j<=5;j++) for(k=j+1;k<=5;k++) x++; cout<<"5个球的取法有"<<x<<"种"<<endl; return 0; }