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为了在日志文件中写入标准格式的时间。要将时间(Now() 转换到字符格式 " YYYY-MM-DD hh:mm:ss zzz"
就编写了此函数，delphi系统自身也带了转换函数 formatDateTime('YYYY-MM-DD hh:mm:ss zzz',Now())
也可以实现此功能。考虑到我这个是固定格式的转换函数，作进一步的优化。
//实际测试效果
运行 1,000，000 次 FormatDateTime()===>2825ms
sfNowToBuf() ==>545
procedure sfNowToBuf(const OutBuf:PChar;BufSize:Integer);
const
strDay:string =
'010203040506070809101112131415161718192021222324252627282930' +
'313233343536373839404142434445464748495051525354555657585960' +
'6162636465666768697071727374757677787980' +
'81828384858687888990919293949596979899';
str10:string = '0123456789';
var
Year,Month,Day,HH,MM,SS,ZZZ:WORD;
P:PChar;
I,J:Integer;
SystemTime: TSystemTime;
lvBuf:array[0..22] of char;
begin
if BufSize <= 0 then
Exit;
P := @lvBuf[0];// OutBuff;
for I := 0 to BufSize - 1 do P[I] := '0';
GetLocalTime(SystemTime);
Year := SystemTime.wYear;
Month := SystemTime.wMonth;
Day := SystemTime.wDay;
HH := SystemTime.wHour;
MM := SystemTime.wMinute;
SS := SystemTime.wSecond;
ZZZ := SystemTime.wMilliseconds;
(* 2012-11-04 17:59
ZZZ := 0;
HH := 0;
MM := 0;
SS := 0;
*)
//Year
I := Year div 1000;
J := Year mod 1000;
P^ := str10[I + 1];Inc(P);
I := J div 100;
P^ := str10[I + 1];Inc(P);
I := J mod 100;
if I > 0 then
begin
P^ := strDay[(I - 1) * 2 + 1];Inc(P);
P^ := strDay[(I - 1) * 2 + 2];Inc(P);
P^ := '-';Inc(P);
end
else begin
P^ := '0';Inc(P);
P^ := '0';Inc(P);
P^ := '-';Inc(P);
end;
//Month
P^ := strDay[(Month - 1) * 2 + 1];Inc(P);
P^ := strDay[(Month - 1) * 2 + 2];Inc(P);
P^ := '-';Inc(P);
//Day
P^ := strDay[(Day - 1) * 2 + 1];Inc(P);
P^ := strDay[(Day - 1) * 2 + 2];Inc(P);
P^ := #32;Inc(P);
//HH
if HH > 0 then
begin
P^ := strDay[(HH - 1) * 2 + 1];Inc(P);
P^ := strDay[(HH - 1) * 2 + 2];Inc(P);
end
else begin
P^ := #48;Inc(P);
P^ := #48;Inc(P);
end;
P^ := ':';Inc(P);
//MM
if MM > 0 then
begin
P^ := strDay[(MM - 1) * 2 + 1];Inc(P);
P^ := strDay[(MM - 1) * 2 + 2];Inc(P);
end
else begin
P^ := #48;Inc(P);
P^ := #48;Inc(P);
end;
P^ := ':';Inc(P);
//SS
if SS > 0 then
begin
P^ := strDay[(SS - 1) * 2 + 1];Inc(P);
P^ := strDay[(SS - 1) * 2 + 2];Inc(P);
end
else begin
P^ := #48;Inc(P);
P^ := #48;Inc(P);
end;
P^ := #32;Inc(P);
//ZZZ
Year := ZZZ div 100;
Month := ZZZ mod 100;
P^ := str10[Year + 1];Inc(P);
if Month > 0 then
begin
P^ := strDay[(Month - 1) * 2 + 1];Inc(P);
P^ := strDay[(Month - 1) * 2 + 2];
end
else begin
P^ := '0';Inc(P);
P^ := '0';
end;
if BufSize >23 then BufSize := 23;
P := OutBuf;
for I := 0 to BufSize - 1 do P[I] := lvBuf[I]
end;
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