Question

/*
 * Application the reads an integer and prints sum of all even integers between two and input    value
 */

import java.util.Scanner;

public class evenNumbers{

  public static void main(String [] args){
    int number;
    Scanner scan = new Scanner(System.in);
    System.out.println("Enter an Integer greater than 1:");
    number = scan.nextInt();
    printNumber(number);
  }// end main


  /*declares an int variable called number and displays it on the screen*/
  public static void printNumber(int number){
    if (number < 2){
      System.out.println("Input value must not be less than 2");
    }
    int sum = 2;
     if(number % 2==0){
       sum+= number;
     }
     System.out.println("Sum of even numbers between 2 and " + number + " inclusive is: " + sum);

  }//end printnumber
}

我需要计算输入数字的总和2，但是，它只取最后一个数字并加2。有人帮我解决这个问题。

Answer 1

你需要一个循环。您的评论暗示了正确的方向，但您应该查看Java教程，了解如何正确编写'for'循环。有三个部分：初始声明，终止条件和循环步骤。请记住，++运算符只向变量添加一个。您可以使用+ =添加其他值。如果使用+ =向循环变量添加不同的值（如2），则可以跳过偶数的“if”测试。您可以使用＆lt; =和＆gt; =比较运算符（对于基元）测试包含边界。所以你想要这样的东西（伪代码，而不是Java）：

 input the test value 
 Optional: reject invalid test value and **exit with message if it is not valid!** 
 initialize the sum variable to zero
 for ( intialize loop variable to 2; test that loop var <= test value; add 2 to loop var ) 
 { 
    add 'number' to the sum variable 
 } 
 display the sum

Answer 2

 int sum = 0;
 for (int current = 2; current <= number; current += 2)
    sum += current;

我需要将两个包含在输入值中

2 个答案: