计算两个日期相差多少天

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 
 4 #define DayOfyear 365
 5 
 6 #define ISLEAP(year) ((year % 4 = 0 && year % 100 != 0) || year % 400 == 0)
 7 
 8 int isLeap(int year);
 9 int dayOftheYear(int year, int month, int day);
10 int diff(int year1, int month1, int day1, int year2, int month2, int day2);
11 int main()
12 {
13     int year1, month1,day1,
14         year2,month2,day2;
15 
16     while(printf("input two dates:XXXX XX XX\t XXXX XX XX\n"),scanf_s("%d %d %d %d %d %d",&year1,&month1,&day1,&year2,&month2,&day2) == 6)
17     {
18         printf("The days between the two dates is %d\n",diff(year1,month1,day1,year2,month2,day2));
19     }
20     system("pause");
21     return 0;
22 }
23 //判断闰年
24 int isLeap(int year)
25 {
26     if((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
27         return 1;//为闰年
28     else
29         return 0;//不是闰年
30 }
31 
32 //计算某个日期在该年第多少天
33 int dayOftheYear(int year, int month, int day)
34 {
35     int sum = 0;//记录天数
36     int index_month;//遍历月份的下标
37     if(month < 1 || month > 12 || day < 1 || day > 31)
38     {
39         printf("The date is illegal\n");
40         system("pause");
41         return 0;
42     }
43     for(index_month = 1; index_month < index_month; index_month++)
44     {
45         switch(index_month)
46         {
47         case 1:
48         case 3:
49         case 5:
50         case 7:
51         case 8:
52         case 10:
53         case 12:
54             sum += 31;
55             break;
56         case 4:
57         case 6:
58         case 9:
59         case 11:
60             sum += 30;
61             break;
62         case 2:
63             if(isLeap(year) == 1)
64                 sum += 29;
65             else
66                 sum += 28;
67             break;
68         }
69     }
70     sum += day;
71     return sum;
72 }
73 
74 int diff(int year1, int month1, int day1, int year2, int month2, int day2)
75 {
76     int sum = 0;//记录两个日期的天数
77     int index_year;//遍历年数
78     int num_leap = 0;//记录闰年数
79 
80     for(index_year = year1; index_year < year2; index_year++)
81     {
82         if(isLeap(index_year) == 1)
83             num_leap++;
84     }
85     sum = num_leap + (year2 - year1) * DayOfyear + dayOftheYear(year2,month2,day2) - dayOftheYear(year1,month1,day1);
86     return sum;
87 }