一个Date类

 1 #ifndef DATE_H_
 2 #define DATE_H_ 
 3 
 4 #include <string>
 5 
 6 class Date
 7 {
 8     public:
 9         Date();
10         Date(int year, int month, int day);
11         
12         void assertValid() const;
13         bool isValid() const;
14         bool isLeapYear() const;
15         int calDaysOfYear() const;
16         int calLeftDaysOfYear() const;
17         int compareDate(const Date &other) const;
18 
19         void setDate(int year, int month, int day);
20         void setToday();
21 
22         std::string toString() const;
23         std::string toFormatString() const;
24 
25 
26         int getYear() const
27         { return year_; }
28         int getMonth() const
29         { return month_; }
30         int getDay() const
31         { return day_; }
32 
33         static int differenceDate(const Date &t1, const Date &t2);
34 
35     private:
36         int year_;
37         int month_;
38         int day_;
39 
40         static const int kDaysOfMonth[2][12];
41         static const std::string kNameOfMonth[12];
42 };
43 
44 #endif  /*DATE_H_*/

  1 #include "Date.h"
  2 #include <stdio.h>
  3 #include <stdlib.h>
  4 #include <time.h>
  5 using namespace std;
  6 
  7 
  8 const int Date::kDaysOfMonth[2][12] = 
  9 {
 10     {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
 11     {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
 12 };
 13 
 14 const string Date::kNameOfMonth[12] = 
 15 {
 16     "January", "February", "March", "April", "May", "June", "July",
 17     "August", "September", "October", "November", "December"
 18 };
 19 
 20 
 21 Date::Date()
 22     :year_(0),
 23      month_(0),
 24      day_(0)
 25 {
 26 
 27 }
 28 
 29 Date::Date(int year,
 30            int month,
 31            int day)
 32     :year_(year),
 33      month_(month),
 34      day_(day)
 35 {
 36 }
 37 
 38 bool Date::isLeapYear() const
 39 {
 40     return (year_%4 == 0 && year_%100 != 0) || year_%400 == 0;
 41 }
 42 
 43 bool Date::isValid() const
 44 {
 45     return year_ > 0 
 46            && month_ > 0
 47            && month_ <= 12
 48            && day_ > 0
 49            && day_ <= kDaysOfMonth[isLeapYear()][month_-1];
 50 }
 51 
 52 void Date::assertValid() const
 53 {
 54     if(!isValid())
 55         abort();
 56 }
 57 
 58 int Date::calDaysOfYear() const
 59 {
 60     assertValid();
 61     int leap = isLeapYear();
 62     int result = 0;
 63     for(int i = 1; i < month_; ++i)
 64     {
 65         result += kDaysOfMonth[leap][i-1];
 66     }
 67     result += day_;
 68 
 69     return result;
 70 }
 71 
 72 int Date::calLeftDaysOfYear() const
 73 {
 74     bool leap = isLeapYear();
 75     int days = calDaysOfYear();
 76     if(leap == true)
 77         return 366 - days;
 78     else
 79         return 365 - days;
 80 }
 81 
 82 int Date::compareDate(const Date &other) const
 83 {
 84     assertValid();
 85     other.assertValid();
 86 
 87     int res = year_ - other.year_;
 88     if(res == 0)
 89         res = month_ - other.month_;
 90     if(res == 0)
 91         res = day_ - other.day_;
 92 
 93     return res;
 94 }
 95 
 96 
 97 void Date::setDate(int year, int month, int day)
 98 {
 99     year_ = year;
100     month_ = month;
101     day_ = day;
102 }
103 
104 void Date::setToday()
105 {
106     time_t t = time(NULL);
107     struct tm *pt = localtime(&t);
108     if(pt == NULL)
109     {
110         perror("localtime");
111         exit(EXIT_FAILURE);
112     }
113 
114     year_ = pt->tm_year + 1900;
115     month_ = pt->tm_mon + 1;
116     day_ = pt->tm_mday;
117 }
118 
119 string Date::toString() const
120 {
121     assertValid();
122     //2009 7/31
123     char text[100] = {0};
124     snprintf(text, sizeof text, "%04d %02d %02d", year_, month_, day_);
125     return string(text);
126 }
127 
128 string Date::toFormatString() const
129 {
130     assertValid();
131     //22 September 2014
132     char text[1024] = {0};
133     snprintf(text, sizeof text, "%d %s %04d", day_, kNameOfMonth[month_-1].c_str(), year_);
134     return string(text);
135 }
136 
137 
138 int Date::differenceDate(const Date &d1, const Date &d2)
139 {
140     Date t1, t2;  //t1 < t2
141     bool minus = false;
142     int days = 0;
143 
144     int diff = d1.compareDate(d2);
145     if(diff == 0)
146         return 0;
147     else if(diff < 0) //d1 < d2
148     {
149         t1 = d1;
150         t2 = d2;
151         minus = true;
152     }
153     else if(diff > 0)
154     {
155         t1 = d2;
156         t2 = d1;
157         minus = false;
158     }
159 
160 
161     //只需比较t1与t2
162     //这里保证t1 < t2
163     //只需计算出天数的差距
164 
165     if(t1.year_ == t2.year_) //同一年
166         days = t2.calDaysOfYear() - t1.calDaysOfYear();
167     else
168     {
169         days += t1.calLeftDaysOfYear(); //t1剩余的天数
170         for(int i = t1.year_+1; i <= t2.year_-1 ; ++i)
171         {
172             bool leap = (i%4 == 0 && i%100 != 0) || i%400 == 0;
173             days += (leap == true ? 366 : 365); 
174         }
175         days += t2.calDaysOfYear();   //t2的天数
176     }
177 
178     if(minus == true)
179         return -1 * days;
180     else
181         return days;
182 }