C + + Date & Time

The C + + standard library does not provide a so-called date type. C + + inherits the structure and functions used for the date and time operations of the language.

In order to use date and time-related functions and structures, you need to reference the header file in a C + + program .
There are four time-related types: clock_t, time_t, size_t, and TM. Types clock_t, size_t, and time_t can represent system time and date as some sort of integer.
The structure Type TM holds the date and time in the form of a C structure, the TM structure is defined as follows:

struct tm {  int tm_sec;   // 秒，正常范围从 0 到 59，但允许至 61  int tm_min;   // 分，范围从 0 到 59  int tm_hour;  // 小时，范围从 0 到 23  int tm_mday;  // 一月中的第几天，范围从 1 到 31  int tm_mon;   // 月，范围从 0 到 11  int tm_year;  // 自 1900 年起的年数  int tm_wday;  // 一周中的第几天，范围从 0 到 6，从星期日算起  int tm_yday;  // 一年中的第几天，范围从 0 到 365，从 1 月 1 日算起  int tm_isdst; // 夏令时}

Current date and time

The following instance gets the date and time of the current system.

#include <iostream>#include <ctime> using namespace std; int main( ){    /* 基于当前系统的当前日期/时间 */    time_t now = time(0);        /* 把 now 转换为字符串形式 */    char* dt = ctime(&now);        cout << "本地日期和时间：" << dt << endl;        return 0;}

Format time using Structure TM

The TM structure is especially important when dealing with date and time-related operations in C + +. The TM structure holds the date and time in the form of a C structure. Most time-related functions use the TM structure. The following example uses a TM structure and various date and time-related functions.

#include <iostream>#include <ctime> using namespace std; int main(){   /* 基于当前系统的当前日期/时间 */   time_t now = time(0);    cout << "1970 到目前经过秒数:" << now << endl;    tm *ltm = localtime(&now);    /* 输出 tm 结构的各个组成部分 */   cout << "年: "<< 1900 + ltm->tm_year << endl;   cout << "月: "<< 1 + ltm->tm_mon<< endl;   cout << "日: "<<  ltm->tm_mday << endl;   cout << "时间: "<< ltm->tm_hour << ":";   cout << ltm->tm_min << ":";   cout << ltm->tm_sec << endl;      return 0;}

Complements the important functions of date and time in C + +:

Serial Number	Functions & Descriptions
1	time_t time (time_t *time) This function returns the current calendar times of the system, the number of seconds elapsed since January 1, 1970. If the system does not have time, it returns. 1.
2	Char ctime (const time_t time), which returns a string pointer representing the local times, as a string of day month, Hours:minutes:seconds Year\n\0.
3	struct TM localtime (const time_t time); The function returns a pointer to the TM structure representing local times.
4	clock_t clock (void); This function returns the time that the processor clock was used by the program execution (typically the beginning of the program). Returns the. 1 if the time is not available.
5	char * asctime (CONST struct TM * time); the function returns a pointer to a string containing information stored in the structure that time points to, returned in the form: Day Month date Hours:minutes:secon DS year\n\0.
6	struct TM gmtime (const time_t time); The function returns a pointer to the hour, which is the TM structure, expressed in Coordinated Universal Time (UTC), which is also known as GMT (GMT).
7	time_t mktime (struct TM *time); This function returns the calendar time, which is the amount of time that is stored in the structure that is pointed to.
8	Double Difftime (time_t time2, time_t time1); The function returns the number of seconds between time1 and Time2.
9	size_t strftime (); This function can be used to format the date and time for the specified format.

Reference from "Rookie Tutorial"

C + + Date & Time