C++第四次作业

项目一：星号图

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

项目二：乘法口诀表

#include <iostream>using namespace std;int main(){ int i,j,m; for(i=1;i<=9;i++) {  for(j=1;j<=i;j++)  {   m=j*i;   cout<<i<<'*'<<j<<'='<<m<<" ";  }  cout<<endl; } return 0;}

项目三：分数的累加

#include<iostream>using namespace std;int main(){   double i,k=1,j=0;   for(i=1;i<=19;i=i+2)   {       j=j+(i/(i+2))*k;       k=-k;   }       cout<<"j="<<j<<endl;    return 0;}