c++作业4

#include<iostream>
using namespace std;
int main()
{
int i,sum=0;
for(i=1;i<=1000;i++)
{
if(i%2==0)
sum=sum+i;
}
cout<<"1000以内的偶数和是"<<sum<<endl;
return 0;
}

#include<iostream>
using namespace std;
int main()
{
int i=0,sum=0;
while(i<=1000)
{
i=i++;
if(i%2==0)
sum=sum+i;
}
cout<<"1000以内的偶数和是"<<sum<<endl;
return 0;
}

#include<iostream>
using namespace std;
int main()
{int i=0,sum=0;
do
{
i++;
if(i%2==0)
sum=sum+i	;
}while(i<1000);
cout<<"1000以内的偶数和是"<<sum<<endl;
return 0;
}

#include<iostream>
using namespace std;
int main()
{
int a,b;
for(b=1;b<=5;b++)
cout<<" ";
cout<<"*\n";
for(a=2;a<=5;a++)
{
for(b=1;b<=6-a;b++)
cout<<" ";
cout<<"*";
for(b=1;b<=2*(a-1)-1;b++)
cout<<" ";
cout<<"*\n";
}
for(b=1;b<=11;b++)
cout<<"*";
cout<<endl;
return 0;
}

#include<iostream>
using namespace std;
int main()
{
int a,b,product;
for(a=1;a<=9;a++)
{
for(b=1;b<=a;b++)
{	product=a*b;
cout<<a<<"*"<<b<<"="<<product<<" \t";
}
cout<<endl;
}
return 0;
}