StartOfAYear - C++ Builder

C++ Builder 参考手册 ➙ System::Dateutils ➙ StartOfAYear

某一年的开始时间，这一年的 1 月 1 日 00:00:00.000

头文件：#include <System.DateUtils.hpp>
命名空间：System::Dateutils
函数原型：

System::TDateTime __fastcall StartOfAYear(const System::Word AYear);

参数：

• AYear：年，1 - 9999；

返回值：

• AYear 年的开始时间，这一年的 1 月 1 日 00:00:00.000；
• 比较函数 StartOfAYear 和 StartOfTheYear：
  • StartOfAYear 的参数是一个整数年；
  • StartOfTheYear 的参数是日期时间；
  只要这两个函数参数的年相同，返回值就相同。

例：

#include <System.DateUtils.hpp>
void __fastcall TForm1::Button1Click(TObject *Sender)
{
    TDateTime dt = Sysutils::Now();
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", dt));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", StartOfTheYear(dt)));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", EndOfTheYear(dt)));

    unsigned short iYear = Dateutils::YearOf(dt);
    Memo1->Lines->Add(iYear);
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", StartOfAYear(iYear)));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", EndOfAYear(iYear)));
}

运行结果：

相关：

• System::Dateutils::StartOfTheYear
• System::Dateutils::EndOfTheYear
• System::Dateutils::StartOfTheMonth
• System::Dateutils::EndOfTheMonth
• System::Dateutils::StartOfTheWeek
• System::Dateutils::EndOfTheWeek
• System::Dateutils::StartOfTheDay
• System::Dateutils::EndOfTheDay
• System::Dateutils::StartOfAYear
• System::Dateutils::EndOfAYear
• System::Dateutils::StartOfAMonth
• System::Dateutils::EndOfAMonth
• System::Dateutils::StartOfAWeek
• System::Dateutils::EndOfAWeek
• System::Dateutils::StartOfADay
• System::Dateutils::EndOfADay
• System::Dateutils::DaysInYear
• System::Dateutils::DaysInAYear
• System::Dateutils::DaysInMonth
• System::Dateutils::DaysInAMonth
• System::Dateutils::WeeksInYear
• System::Dateutils::WeeksInAYear
• System::Dateutils

C++ Builder 参考手册 ➙ System::Dateutils ➙ StartOfAYear