长除法 1/N 算法使用字符串存储数字，当太长时创建 symbols/letters

Question

我想做一个专门针对1/N的长除法算法。我已经让代码正常工作，但是当存储数字的字符串长度达到 ~>20 位时，数据类型正在做一些“时髦的事情”。

您可以更改 b 变量以测试任何其他分数。

这是我的代码：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main()
{
    int a = 1;
    int b = 666;
    int c = 0;
    int d = 1;
    int z = 0;

    char *decimals = "0.";
    size_t len = 2;

    while (d>0)
    {
        printf("a: %d   ",a);
        printf("b: %d   ",b);
        printf("c: %d   ",c);
        printf("d: %d\n",d);
    
        if(a<b)
        {
            a = a*10;
        
            if(a<b)
            {
                len = len + 2;
            
                char *temp = calloc(len, sizeof(char));
                sprintf(temp, "%s%d",decimals,z);
                decimals = temp;
                printf("%s\n\n", decimals);
            }
            else
            {
                c = a/b;
                d = a-b*c;
                a = d;
            
                char *temp = calloc(len, sizeof(char));
                sprintf(temp, "%s%d",decimals,c);
                decimals = temp;
                printf("%s\n\n", decimals);
            }
        }
    }   
    free(decimals);
}

CMD 输出：

是什么导致出现 # 字符？如果运行时间更长，会出现更多随机 letter/symbols。

Answer 1

我认为内存分配的方式有问题。您最终在 else 语句中写入超过分配的内存量。长度没有在应该扩展的时候扩展。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    int a = 1;
    int b = 666;
    int c = 0;
    int d = 1;
    int z = 0;
    int k = 0;

    char * decimals = (char*)malloc(sizeof(char) * 3);
    if (!decimals)
    {
        printf("alloc failed!");
        return 1;
    }
    sprintf(decimals, "0.");

    size_t len = 2;
    while (d > 0 && k++ < 1000)
    {

        printf("a: %d   ", a);
        printf("b: %d   ", b);
        printf("c: %d   ", c);
        printf("d: %d\n", d);

        if (a < b)
        {
            a = a * 10;

            if (a < b)
            {
                len += 2;
                char *temp = (char *)malloc(sizeof(char) * len);
                if (!temp)
                {
                    printf("alloc failed!");
                    break;
                }

                snprintf(temp, len, "%s%d", decimals, z);
                free(decimals);
                decimals = temp;
                printf("%s\n\n", decimals);
            }
            else
            {
                c = a / b;
                d = a - b * c;
                a = d;

                len += 2;
                char *temp = (char *)malloc(sizeof(char) * len);
                if (!temp)
                {
                    printf("alloc failed!");
                    break;
                }
                snprintf(temp, len, "%s%d", decimals, c);
                free(decimals);
                decimals = temp;
                printf("%s\n\n", decimals);
            }
        }
    }

    free(decimals);
}

长除法 1/N 算法使用字符串存储数字，当太长时创建 symbols/letters

Long division 1/N algorithm using string to store digits, creates symbols/letters when too long

c

types

symbols