.NET Framework的DateTime型别本身就有转Day,Hour,Minute等Method，所以要转十分方便。但C/C++呢?



C/C++的<time.h>(<ctime>)提供了localtime()，可将sec一次转成所要的信息，该struct定义如下

 1struct tm {
 2  int tm_sec;    // sec.
 3  int tm_min;   // min.
 4  int tm_hour;  // hour
 5  int tm_mday; // day
 6  int tm_mon;  // month
 7  int tm_year;  // year
 8  int tm_wday; // day of week
 9  int tm_yday;  // day of year
10  int tm_isdst;  // 夏令时间 
11}

以下为localtime()的范例程序

本范例为了抓到0.1秒，所以才用了clock()，一般若只想抓到sec.，用time()即可。 

1/**//* 
 2(C) OOMusou
 4Filename    : localtime.cpp
 5Compiler    : Visual C++ 8.0
 6Description : Demo how to use localtime() to get min part & hour part
 7Release     : 11/26/2006
 8*/
 9#include <iostream>
10#include <ctime>
11
12// Time-wasting function
13void foo();
14// Get specified floating point number from double
15int getDigitFromDouble(double, int);
16
17int main() {
18  clock_t t1 = clock();
19  // Time-wasting function
20  foo();
21  clock_t t2 = clock();
22
23  // Total sec., but including floating part, not only integer
24  double sec = (double)(t2 - t1) / CLOCKS_PER_SEC;
25  // 0.1 sec. part
26  int   ssec = getDigitFromDouble(sec,1);
27  // Convert dobule to const time_t, 
28  // Since localtime needs (const time_t*) parameter
29  const time_t time_t_sec = (time_t)sec;
30  // localtime() return (struct *tm)
31  struct tm* ts = localtime(&time_t_sec);
32
33  std::cout << "Total sec:" << sec << std::endl;
34  std::cout << "min:" << ts->tm_min << std::endl;
35  std::cout << "sec:" << ts->tm_sec << std::endl;
36  std::cout << "0.1 sec:" << ssec << std::endl;
37
38  return 0;
39}
40
41void foo() {
42  for(int i = 0; i != 1000000; ++i) 
43    for(int j = 0; j != 100000; ++j);
44}
45
46// get specified floating point number from double
47int getDigitFromDouble(double d, int n) {
48  int t = 1;
49  for(int j = 0; j != n-1; ++j) {
50    t *= 10;
51  }
52
53  d = d * t;
54  int i = (int)d;
55
56  return (int)((double)(d-i)*10);
57}