C程序 寻找两个整数之间的阿姆斯特朗数字

一个有n个数字的正整数被称为阶数为n的阿姆斯特朗数（阶数是数字的数量），如果

abcd… = pow(a,n) + pow(b,n) + pow(c,n) + pow(d,n) + …

在这里，我们将建立一个C程序来打印两个整数之间的阿姆斯特朗数字。

例子。

153 is an Armstrong number

1*1*1 + 5*5*5 + 3*3*3 = 153

370 is an Armstrong Number

3*3*3 + 7*7*7 + 0*0*0 = 370 

输入:

lowerlimit = 100 
higherlimit = 400 

输出:

153 370 371

下面是打印用户提供的下限和上限之间所有阿姆斯特朗数字的程序。

// C Program to Demonstrate
// Armstrong numbers between
// two integers
#include <math.h>
#include <stdio.h>
  
int power(int x, unsigned int y)
{
    // Initialize result
    int res = 1;
  
    while (y > 0) {
        // If y is odd, multiply
        // x with result
        if (y & 1)
            res = res * x;
  
        // y must be even now
        y = y >> 1; // y = y/2
        x = x * x; // Change x to x^2
    }
    return res;
}
  
int main()
{
    int lowerlimit, higherlimit;
    printf("Enter lowerlimit and Higher limit:\n ");
    scanf("%d%d", &lowerlimit, &higherlimit);
  
    for (int i = lowerlimit + 1; i < higherlimit; ++i) {
        int x = i;
        int n = 0;
        
        // number of digits calculation
        while (x != 0) {
            x /= 10;
            ++n;
        }
        int powersum = 0;
        x = i;
        // finding the sum of n
        // th power of its digits
        while (x != 0) {
            int digit = x % 10;
            powersum += power(digit, n);
            x /= 10;
        }
        // checking if the obtained
        // number is armstrong or
        // not
        if (powersum == i)
  
            // printing the result
            printf("%d ", i);
    }
    printf("\n");
    return 0;
}

输出:

Enter lowerlimit and Higher limit: 100 400
153 370 371