Question

我需要创建一个程序，显示用户输入的两个数字之间的偶数和的整数之和。

这是我到目前为止所做的，它不起作用！？

请指出我正确的方向！

//Advanced30.cpp - displays the sum of the even integers between and 
//including two numbers entered by the user
//Created/revised by <your name> on <current date>

#

    include <iostream>
    using namespace std;

    int main()
    {
        // declare variables
        int num1 = 0;
        int num2 = 0;
        int sum= 0;

        cout << "Enter the First Number:" << endl;  
        cin >> num1;     
        cout << "Enter the Second Number:" << endl;    
        cin >> num2;      


        for (num2 = num1; num1 <= num2; num1 += 2) sum += num1;       
        num1 = num1 % 2 == 0 ? num1 : num1+1; 
        num2 = num2 % 2 == 0 ? num2 : num2-1;

        return 0;

Answer 1

尝试完成您的计算机在进行循环时正在执行的操作。在纸上做。跟踪num2，num1及其值。你会很快看到问题所在。

Answer 2

尝试循环

for(; num1<=num2;num1++)
{
if(num1%2==0)
 sum=sum+num1
}

Answer 3

    for (num2 = num1; num1 <= num2; num1 += 2) sum += num1;

你已经覆盖了你的停止点。：）

我还建议更有意义的名字：

int start=0;
int real_start=0;
int stop=0;
int sum=0;

/* ... */

real_start = (start % 2) ? start+1 : start;

for (int i = real_start; i <= stop; i+=2) sum += i;

/* ... */

甚至整数问题的总和

3 个答案: