试验一

#include<iostream>
using namespace std;
int main()
{char choice,c;
while(1)
{cout <<"menu:A(dd) D(elete) S(ort) Q(uit), select one:";
cin>>c;
choice=toupper(c);
if(choice=='A')
{cout<<"数据已经增加."<<endl;
continue;}
else if(choice=='D')
{cout<<"数据已经删除."<<endl;
continue;}
else if(choice=='S')
{cout<<"数据已经排序."<<endl;
continue;}
else if(choice=='Q')
break; 
}
return 0;
}

#include<iostream>

using namespace std;
int main()
{char x;
while(true)
{cout<<"menu: A(dd) D(elste) S(ort) Q(uit),Select one:"<<endl;
cin>>x;
switch(x){
	case 'A':
		{cout<<"数据已经增加"<< endl;continue;}
	case 'D':
		{cout<<"数据已经删除"<< endl;continue;}
	case 'S':			
		{cout<<"数据已经排序"<< endl;continue;}
	case 'Q':
	     break;

}
break;
 } 
 return 0;
}

　　

 

#include<iostream>
#include<math.h>
using namespace std;
int main()
{int i=2,j,n=0;
 while(i<=100)
      {j=2;
       while(j<=sqrt(i))
            {if(i%j==0)
               break;
             j++;
            }
       if(j>=sqrt(i)) 
         {cout<<i<<"\t";
          n++;
         }
       if(n%5==0&&n!=0)
         {n=0;
          cout<<endl;
         }
       i++; 
      }
 return 0;
}

#include<iostream>
#include<math.h>
using namespace std;
int main()
{int i=2,j,n=0;
 do{j=2;
    do{if(i%j==0)
       break;
       j++;
      }while(j<=sqrt(i));
    if(j>=sqrt(i)) 
      {cout<<i<<"\t";
       n++;
      }
    if(n%5==0&&n!=0)
      {n=0;
       cout<<endl;
      }
    i++; 
   }while(i<=99);
 return 0;
}

　　

#include<iostream>
#include<math.h>
using namespace std;
int main()
{int i,j,n=0;
 for(i=2;i<=100;i++)
    {j=2;
     for(j=2;j<=sqrt(i);j++)
        {if(i%j==0)
         break;
        }
     if(j>=sqrt(i)) 
       {cout<<i<<"\t";
        n++;
       }
     if(n%5==0&&n!=0)
       {n=0;
        cout<<endl;
       }
    }
 return 0;
}

　　

#include<iostream>
#include<cstdlib>
#include<ctime>
using namespace std;
int main()
{int a,b;
 srand(time(0));
 a=rand()%100;
 cout<<"请输入一个数(1-100): ";
 cin>>b;
 while (true)
 {if (a<b)
    {cout<<"你输入的数大了"<<endl;
     cin>>b;    
    }
  else if (a>b)
    {cout<<"你输入的数小了"<<endl;
     cin>>b;    
    }
  else 
    {cout<<"你猜对了"<<endl;
     break;    
    }
 }
return 0;    
}

　　

#include<iostream>
#include<cstdlib>
#include<ctime>
using namespace std;
int main()
{int a,b;
 srand(time(0));
 a=rand()%100;
 cout<<"请输入一个数(1-100): ";
 cin>>b;
 do
 {if (a<b)
    {cout<<"你输入的数太大了"<<endl;
     cin>>b;    
    }
  else if (a>b)
    {cout<<"你输入的数太小了"<<endl;
     cin>>b;    
    }
  else 
    {cout<<"你猜对了"<<endl;
     break;    
    }
 }while (true);
 return 0;
}

#include<iostream>
using namespace std;
int main()
{ int i,j,k,r=0;
  int c1,c2,c3;
  cout<<"定义红色为 0,黄色为 1,蓝色为 2,白色为 3,黑色为 4"<<endl; 
  int a[5]={0,1,2,3,4};
  for(i=0;i<=4;i++)
    {c1=a[i];
     for(j=i+1;j<=4;j++)
       {c2=a[j];
        for(k=j+1;k<=4;k++)
          {c3=a[k];
           r++;
           cout<<c1<<c2<<c3<<endl;}
        c2=a[j]; 
       } 
      c1=a[i];
     }
  cout<<"一共有"<<r<<"种取法"<<endl;
  return 0;
}