几何计算器V1s

int o;

cout<<"请问你要计算以下那种计算：\n  1.周长 2.面积 3.表面积 4体积。\n";

cin>>o;

if(o==1){
	cout<<"请选择：1.长方形 2.正方形 3.三角形 4.平行四边形 5.梯形 6.n边形\n";

	int n;

	cin>>n;

	if(n==1){
		cout<<"请输入长方形的长and宽。\n";

		double c,k;

		cout<<"长：";


		cin>>c;

		cout<<"\n宽：";

		cin>>k;

		cout<<"\n长方形的周长为"<<(c+k)*2<<"。\n";

	}
	else if(n==2){

		cout<<"请输入正方形的边长。\n";

		double x;

		cout<<"边长：" ;

		cin>>x;

		cout<<"正方形的周长为"<<4*x<<"。\n";
	}
	else if(n==3){
		cout<<"请输入三角形的三条边长。\n";

		double k,l,j;

		cout<<"边长：";

		cin>>k>>l>>j;

		cout<<"三角形的周长为" <<k+j+l<<"。\n";
	}
	else if(n==4){
		cout<<"请输入平行四边形的底and腰。\n";

		double d,y;

		cout<<"底：";

		cin>>d;

		cout<<"腰：";

		cin>>y;

		cout<<"平行四边形的周长为"<<2*(d+y)<<"。\n";
	}
	else if(n==5){

	cout<<"请输入梯形的上，下底and2条腰。\n";

	int y1,y2,d1,d2;

	cout<<"上底：";

	cin>>d1;

	cout<<"下底：";

	cin>> d2;

	cout<<"腰：";

	cin>>y1>>y2;

	cout<<"梯形的周长为"<<d1+d2+y1+y2<<"。\n";

	}else if(n==6){

		int m,k=0,a[20000];

		cout<<"这个n边形有几条边？";

		cin>>m;

		for(int i=3;i<=n;i++){

			cout<<"第"<<i-2<<"边长";

			cin>>a[i];

			cout<<"。";

			k+=a[i];
		}
		cout<<"这个n边形的周长为"<<k<<"。\n";
	}
	else {
		cout<<"无";

	}
	cout<<"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"; 
}

return 0;