StartOfAMonth - C++ Builder

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

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某个月的开始时间，这一个月的 1 日 00:00:00.000

头文件：#include
命名空间：System::Dateutils
函数原型：

System::TDateTime __fastcall StartOfAMonth(const System::Word AYear, const System::Word AMonth);

参数：

• AYear：年，1 - 9999；
• AMonth：月，1 - 12；

返回值：

• AYear 年 AMonth 月的开始时间，这一个月的 1 日 00:00:00.000；
• 比较函数 StartOfAMonth 和 StartOfTheMonth：
  • StartOfAMonth 的参数是整数年、月；
  • StartOfTheMonth 的参数是日期时间；
  只要这两个函数参数的年月和日期的年月相同，返回值就相同。

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例：

#include 
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", StartOfTheMonth(dt)));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", EndOfTheMonth(dt)));

    unsigned short iYear = Dateutils::YearOf(dt);
    unsigned short iMonth = Dateutils::MonthOf(dt);
    Memo1->Lines->Add(String().sprintf(L"%d年%d月", iYear, iMonth));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", StartOfAMonth(iYear,iMonth)));
    Memo1->Lines->Add(FormatDateTime(L"yyyy/mm/dd hh:nn:ss.zzz", EndOfAMonth(iYear,iMonth)));
}

运行结果：

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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

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