计算正整数n1到n2的累加和（n1、n2的值由键盘输入）。

以下是两种计算正整数n1到n2的累加和的例子：

1. Java实现：

import java.util.Scanner;

public class CalculateSum {
    public static void main(String[] args) {
        int n1, n2, sum = 0;
        Scanner buf = new Scanner(System.in);
        
        System.out.println("输入正整数n1: ");
        n1 = buf.nextInt();
        
        System.out.println("输入正整数n2: ");
        n2 = buf.nextInt();
        
        for (int i = n1; i <= n2; i++) {
            sum += i;
        }
        
        System.out.println(n1 + "到" + n2 + "的累加和为：" + sum);
    }
}

2. C语言实现：

#include <stdio.h>

int calculateSum(int n1, int n2) {
    int sum = 0;
    
    for (int i = n1; i <= n2; i++) {
        sum += i;
    }
    
    return sum;
}

int main() {
    int n1, n2, sum;
    
    printf("请输入n1的值：");
    scanf("%d", &n1);
    
    printf("请输入n2的值：");
    scanf("%d", &n2);
    
    sum = calculateSum(n1, n2);
    
    printf("%d到%d的累加和为：%d\n", n1, n2, sum);
    
    return 0;
}