Question

我对编码非常陌生，我需要创建一个回文测试，测试数字达到给定的限制。我理解测试数字是否是回文的算法。但是我在循环代码时遇到了问题。输出应如下所示：如果限制是1000：

限制| #indindromes |倒数之和
100 18 3.086147（限制的1/10）
200 28 3.157490（限制的2/10）

一直到用户提供的限制。

我已经启动了代码但是我的代码无限循环。你能告诉我我做错了什么吗？这是我的代码。

#include <stdio.h>
#include <math.h>

int main(void) {
    double num;
    int upperLimit = 0; //Limit of the program.
    int numPalindromes = 0;
    double sum = 0;
    int tempLim;
    int i = 1;

    printf("Enter the limit of the program:");  //Asks for the limit you want the program to go to
    scanf("%d", &upperLimit);

    // We now need to use an algorithm to test whether or not the number is a palindrome.
    while(num <= upperLimit) {
        int temp;
        int rev = 0;
        temp = num;

        while(temp != 0 ){
            rev = rev * 10;
            rev = rev + temp%10; // we need to add the remainder when the number is divided by 10 to the reverse.
            temp = temp/10;
        }
        /*A number is a palindrome if its reverse is equal to itself. Now we must add its reciprocal to the sum and increase the amount of palindromes by 1 if the number is a palindrome */
        if(num == rev) {
            sum = sum + (1/num);
            numPalindromes = numPalindromes + 1;
        }

        while (num <= upperLimit) {
            tempLim = upperLimit * (i/10);
            if (num == tempLim) {
                printf(" %d %d %lf\n", tempLim, numPalindromes, sum);
            }
            i++;
        }
        num++;
    }
}

Answer 1

你有这样一个片段：

while (num <= upperLimit) {
    tempLim = upperLimit * (i/10);
    if (num == tempLim) {
        printf(" %d %d %lf\n", tempLim, numPalindromes, sum);
    }
    i++;
}

但是，在循环内部都没有修改num和upperLimit。因此它永远循环。

Answer 2

 while (num <= upperLimit) {
        tempLim = upperLimit * (i/10);
        if (num == tempLim) {
            printf(" %d %d %lf\n", tempLim, numPalindromes, sum);
        }
        i++;
    }

num没有变化，上限没有变化。所以它无限运行。

如何使这个循环适用于我的回文测试？

2 个答案: