Question

编写一个类，该类创建的对象可以计算等差数列的和

Answer 1

//等差数列只要有首项和公差就行了.#include <iostream>
using namespace std;class CNumbers
{
public:
CNumbers(int a1=0,int d=0);
int Sum(int n);
private:
int m_a1;//首项
int m_d;//公差
};
CNumbers::CNumbers(int a1/* =0 */,int d/* =0 */)
{
m_a1 = a1;
m_d = d;
}
int CNumbers::Sum(int n)
{
int an = m_a1 + (n-1)*m_d;
return (m_a1+an)*n/2;
}
void main()
{
CNumbers a(1,1);
cout<<a.Sum(100)<<endl;
}

Answer 2

class
calculate
{
private
int
t,s;
public
void
calculate()
{
s=0;
}
/*
参数:数列开始,最后一位,增量
返回:int
*/
public
int
total(int
first,int
last,int
increment)//increment为数列增量
{
if(
((last
-
first)
/
increment)
%
1
==0
)
//数列为等差时
{
for(int
j=0;j<(last
-
first)
/
increment
+
1;j++)
{
t
=
j*increment
+
first;
s
=
s
+
t;
}
}
return
s;
}
}
//测试
class
test4
{
public
static
void
main(String
args[])
{
calculate
c
=
new
calculate();//这里创建一个对象
System.out.println(c.total(1,9,4));
//这里调用C对象的total方法
}
}