实验结论

2-28 if...else

#include <iostream>

#include <stdlib.h>

using namespace std;

int main()

{char a;

cout<<"Menu:A(dd) D(elete) S(ort) Q(uit),Select one:";

cin>>a;

while(true)

if (a=='A')

{cout<<"数据已经增加"<<endl;break;}

else if(a=='D')

{cout<<"数据已经删除"<<endl;break;}

else if (a=='S')

{cout<<"数据已经排序"<<endl;break; }

else if (a=='Q')

break;

else

{cout<<"error"<<endl;}

return 0;

}

switch

#include <iostream>

using namespace std;

int main()

{ char c;

while (true)

{cout<<"Menu: A(dd) D(elect) S(ort) Q(uit) Select one: ";cin>>c;

switch(c)

{ case 'A':cout<<"数据已经增加"<<endl;continue;

case 'D':cout<<"数据已经减少"<<endl;continue;

case 'S':cout<<"数据已经排序"<<endl;continue;

case 'Q':break;

}

break;

}

return ;

}

2-29 while

#include <iostream>

#include <cmath>

using namespace std;

int main()

 { int n=,i,f,t=;

   while(n<=)

    {f=;

     for(i=;i<=sqrt(n);i++)

       if(n%i==)

        {f=;

         break;

        }

     if(f==)

       {cout<<"  "<<n;

        t++;

        if(t%==)

         cout<<endl;

       }

     n++;

  }

}

#include <iostream>

#include <cmath>

using namespace std;

int main()

 { int n=,i,f,t=;

   do

    {f=;

     for(i=;i<=sqrt(n);i++)

       if(n%i==)

        {f=;

         break;

        }

     if(f==)

       {cout<<"  "<<n;

        t++;

        if(t%==)

         cout<<endl;

       }

     n++;

  }while(n<=);

}

#include <iostream>

#include <cmath>

using namespace std;

int main()

 { int n=,i,f,t=;

   for(;n<=;)

    {f=;

     for(i=;i<=sqrt(n);i++)

       if(n%i==)

        {f=;

         break;

        }

     if(f==)

       {cout<<"  "<<n;

        t++;

        if(t%==)

         cout<<endl;

       }

     n++;

  }

}

#include <iostream>

using namespace std;

int main()

{ int n=,m;

  cout<<"please guess the nunmber(1-100): ";cin>>m;

  while(n!=m)

    {if(m<n)

      {cout<<"bigger than the number: ";cin>>m;}

     else

      {cout<<"smaller than the number: ";cin>>m;}

    }

  cout<<"You are right!"<<endl;

  return ;

 }

#include <iostream>

using namespace std;

int main()

{ int n=,m;

  cout<<"please guess the nunmber(1-100): ";cin>>m;

  do

    {if(m<n)

      {cout<<"bigger than the number: ";cin>>m;}

     else

      {cout<<"smaller than the number: ";cin>>m;}

    }while(n!=m);

  cout<<"You are right!"<<endl;

  return ;

 }

#include <iostream>

using namespace std;

int main()

{ int i,j,k,r=;

  int c1,c2,c3;

  cout<<"Red: 0,Yellow: 1,Blue: 2,White: 3,Black:4"<<endl;

  int a[]={,,,,};

  for(i=;i<=;i++)

    {c1=a[i];

     for(j=i+;j<=;j++)

       {c2=a[j];

        for(k=j+;k<=;k++)

          {c3=a[k];

           r++;

           cout<<c1<<c2<<c3<<endl;}

        c2=a[j];

       }

      c1=a[i];

     }

  cout<<"取法有："<<r<<"种"<<endl;

  return ;

}