C中不正确的数学输出

Question

我正在编写“Sams 自学 C 编程”第 66 页上的这个非常简单且基本的脚本。

基本上，脚本会询问您几秒钟。
您输入一个数字，然后它会计算它们构成的小时分钟和秒数。

然后我稍微修改了脚本以探索代码并使其不那么枯燥。
修改包括扩大可接受的输入和输出范围。

在下面提供的代码中，我已经用 cmets 来表示原始代码、修改和添加。

最后，在最后，我添加了 cmets 来说明几个非常古怪的输出。

**** 表示对计数进行增量检查 **** ****表示响应输入的非常小的变化（即 1 位），输出会发生巨大变化。

当我随机输入85000000 时，我首先注意到了这个问题。

我已尽一切努力简化代码，以便更容易专注于数学。
我不确定这是数学问题还是错字。

不管怎样，代码如下：

/* Illustrates the modulus operator. */
/* inputs a number of seconds, and converts to hours, minutes, and seconds. */
// minute = 60 seconds                  : 60
// hour = 60 * 60 seconds               : 3600
// day = 24 * 60 * 60 seconds           : 86400
// year = 365 * 24 * 60 * 60 seconds    : 31536000

#include <stdio.h>                                      // from original script

/* Define constants */

#define SECS_PER_MIN 60                                 // from original script
#define MIN_PER_HOUR 60
#define HOURS_PER_DAY 24
#define DAYS_PER_YEAR 365
#define SECS_PER_YEAR 31536000
#define SECS_PER_HOUR 3600                              // from original script
#define SECS_PER_DAY 86400
#define LIMIT 2147438647

unsigned int seconds, minutes, hours, days, years, secs_remain, mins_remain, hours_remain, days_remain;     // modified from original script

int main(void)                                                                                          // from original script
{
    seconds = minutes = hours = days = years = secs_remain = mins_remain = hours_remain = days_remain = 0;
    /* Input the number of seconds. */

    printf( "Enter the number of seconds ( > 0, < %u ): \n", LIMIT );                  // modified from original script
    scanf( "%d", &seconds );                                                                            // from original script

    years = seconds /SECS_PER_YEAR;
    days = seconds / SECS_PER_DAY;
    hours = seconds / SECS_PER_HOUR;                                                                    // from original script
    minutes = seconds / SECS_PER_MIN;                                                                   // from original script
    days_remain = days / DAYS_PER_YEAR;      // ***missing 22643200 seconds, given input: 85000000***
    hours_remain = hours % HOURS_PER_DAY;
    mins_remain = minutes % MIN_PER_HOUR;                                                               // modified from original script
    secs_remain = seconds % SECS_PER_MIN;                                                               // from original script

    printf( "%u seconds is equal to ", seconds );                                                       // from original script

    if ( seconds < SECS_PER_HOUR )
    {
         printf( "%u m, and %u s\n", minutes, secs_remain );
         return 0;
    }
         else if((seconds >= SECS_PER_HOUR ) && (seconds < SECS_PER_DAY ))
         {
              printf( "%u h, %u m, and %u s\n", hours, mins_remain, secs_remain );                  // from original script
              return 0;                                                                             // from original script
         }    
         else if((seconds >= SECS_PER_DAY ) && (seconds < SECS_PER_YEAR ))
         {
              printf( "%u d, %u h, %u m, and %u s\n", days, hours_remain, mins_remain, secs_remain );
              return 0;
         }            
         else if((seconds >= SECS_PER_YEAR ) && (seconds < LIMIT ))
         {
             printf( "%u y %u d, %u h, %u m, and %u s\n", years, days_remain, hours_remain, mins_remain, secs_remain );  // calculation day's inaccurate
             return 0;
         }   
         else if(seconds > LIMIT )
         {
             printf("error: excessive amount of seconds.\n");
             printf("range for seconds must be between 0 and %u!\n", LIMIT );
             printf("If number of seconds exceeds %u, then it is beyond range for type 'int'.\n", LIMIT );
             printf("EXITING seconds program. \n");
             return 1;
         }
    }

// ERROR: 31536000 seconds is equal to 1 y 1 d, 0 h, 0 m, and 0 s
// ERROR: 63072000 seconds is equal to 2 y 2 d, 0 h, 0 m, and 0 s
// ERROR: 70000000 seconds is equal to 2 y 2 d, 4 h, 26 m, and 40 s                         ****
// ERROR: 78840000 seconds is equal to 2 y 2 d, 12 h, 0 m, and 0 s                          ****
// ERROR: 90000000 seconds is equal to 2 y 2 d, 16 h, 0 m, and 0 s                          ****
// ERROR: 92500000 seconds is equal to 2 y 2 d, 14 h, 26 m, and 40 s                        ****
// ERROR: 93750000 seconds is equal to 2 y 2 d, 1 h, 40 m, and 0 s                          ****
// ERROR: 94380000 seconds is equal to 2 y 2 d, 8 h, 40 m, and 0 s                          ****
// ERROR: 94537500 seconds is equal to 2 y 2 d, 4 h, 25 m, and 0 s                          ****
// ERROR: 94576875 seconds is equal to 2 y 2 d, 15 h, 21 m, and 15 s                        ****
// ERROR: 94596562 seconds is equal to 2 y 2 d, 20 h, 49 m, and 22 s                        ****
// ERROR: 94606406 seconds is equal to 2 y 2 d, 23 h, 33 m, and 26 s                        ****
// ERROR: 94607636 seconds is equal to 2 y 2 d, 23 h, 53 m, and 56 s                        ****
// ERROR: 94607943 seconds is equal to 2 y 2 d, 23 h, 59 m, and 3 s                         ****
// ERROR: 94607981 seconds is equal to 2 y 2 d, 23 h, 59 m, and 41 s                        ****
// ERROR: 94607990 seconds is equal to 2 y 2 d, 23 h, 59 m, and 50 s                        ****
// ERROR: 94607995 seconds is equal to 2 y 2 d, 23 h, 59 m, and 55 s                        ****
// ERROR: 94607998 seconds is equal to 2 y 2 d, 23 h, 59 m, and 58 s                        ****
// ERROR: 94607999 seconds is equal to 2 y 2 d, 23 h, 59 m, and 59 s                        ****    ****
// ERROR: 94608000 seconds is equal to 3 y 3 d, 0 h, 0 m, and 0 s                           ****    ****
// ERROR: 94608174 seconds is equal to 3 y 3 d, 0 h, 2 m, and 54 s                          ****
// ERROR: 94608097 seconds is equal to 3 y 3 d, 0 h, 1 m, and 37 s                          ****
// ERROR: 94608251 seconds is equal to 3 y 3 d, 0 h, 4 m, and 11 s                          ****
// ERROR: 94608867 seconds is equal to 3 y 3 d, 0 h, 14 m, and 27 s                         ****
// ERROR: 94611328 seconds is equal to 3 y 3 d, 0 h, 55 m, and 28 s                         ****
// ERROR: 94616250 seconds is equal to 3 y 3 d, 2 h, 17 m, and 30 s                         ****
// ERROR: 94695000 seconds is equal to 3 y 3 d, 0 h, 10 m, and 0 s                          ****
// ERROR: 95000000 seconds is equal to 3 y 3 d, 12 h, 53 m, and 20 s                        ****
// ERROR: 100000000 seconds is equal to 3 y 3 d, 9 h, 46 m, and 40 s                        ****
// ERROR: 122990400 seconds is equal to 3 y 3 d, 12 h, 0 m, and 0 s
// ERROR: 126144000 seconds is equal to 4 y 4 d, 0 h, 0 m, and 0 s

Answer 1

在您的代码行中，

days_remain = days / DAYS_PER_YEAR;    // ***missing 22643200 seconds, given input: 85000000***

这里应该是%而不是/，你写错了。

当我看到你的这部分代码时，我怀疑这可能行不通

else if(seconds > LIMIT )
             {
                 printf("error: excessive amount of seconds.\n");
                 printf("range for seconds must be between 0 and %u!\n", LIMIT );
                 printf("If number of seconds exceeds %u, then it is beyond range for type 'int'.\n", LIMIT );
                 printf("EXITING seconds program. \n");
                 return 1;
              }

请参阅此Validate max integer in scanf 以了解如何验证用户提供的输入。

Answer 2

像这样编辑您的代码： days_remain = 天 % DAYS_PER_YEAR;