c++作业4

（1）项目三：乘法口诀表

#include<iostream>
using namespace std;
int main()
{
int i,j;
cout<<"九九乘法口诀表来啦哟"<<endl;
for(i=1;i<=9;i++)
{
for(j=1;j<=i;j++)
cout<<j<<"*"<<i<<"="<<j*i<<"\t";
cout<<endl;
}
return 0;
}(2)项目四：输出完数
#include<iostream>
using namespace std;
int main()
{
int i=2,j,k;
cout<<"1000以内的一切完数有:";
for(i;i<=1000;i++)
{
k=0;
for(j=1;j<=i/2;j++)
if(i%j==0) k=k+j;
if(k==i) cout<<k<<",";
}
cout<<endl;
return 0;
}
(3)项目六：输出星号图
#include<iostream>
using namespace std;
int main()
{
int i=1,j=1;
for(j;j<=6;j++)
cout<<" ";
cout<<"*"<<endl;
for(i;i<=5;i++)
{
for(j=1;j<=6-i;j++)
cout<<" ";
cout<<"*";
for(j=1;j<=-1+2*i;j++)
cout<<" ";
cout<<"*";
cout<<endl;
}
for(j=1;j<=13;j++)
cout<<"*";
cout<<endl;
return 0;
}