Pascal:从 LPSYSTEMTIME 记录中获取字段 [英] Pascal: Get field from LPSYSTEMTIME record
问题描述
我正在使用 Win32 api 来获取文件的日期和时间.我有一个 LPSYSTEMTIME 结构,我正在尝试打印其 wYear 变量.
我有一个函数 (GetFileDate):
函数 GetFileDate : LPSYSTEMTIME无功检查文件:长;文件时间:LPFILETIME;文件时间返回:LPFILETIME;SystemTimeReturn: LPSYSTEMTIME;开始CheckFile := CreateFile(PChar('main.pas'), GENERIC_READ, FILE_SHARE_READ, NIL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);GetFileTime(CheckFile, FileTime, NIL, NIL);FileTimeToLocalFileTime(FileTime, FileTimeReturn);FileTimeToSystemTime(FileTimeReturn, SystemTimeReturn);GetFileDate := SystemTimeReturn;结尾;
但是当我这样做时...
开始写(GetFileDate.wYear);结尾.
它吐了
<块引用>main.pas(22,20) 错误:非法限定符main.pas(22,20) 致命:语法错误,)"预期但标识符 WYEAR"找到致命:编译中止
对此有什么帮助吗?
LPSYSTEMTIME
是一个指向 SYSTEMTIME
结构的指针.尝试使用 ^
运算符取消引用该指针,例如:
Write(GetFileDate^.wYear);
或者:
Write(GetFileDate()^.wYear);
话虽如此,除了您根本没有进行任何错误处理这一事实之外,您的 GetFileDate()
实现将错误的参数值传递给各种 API 函数.该代码甚至不应该编译,更不用说正确运行了.
试试这个:
函数 GetFileDate : SYSTEMTIME;无功检查文件:处理;文件时间:文件时间;文件时间返回:文件时间;SystemTimeReturn: SYSTEMTIME;获取文件日期结果:系统时间;开始ZeroMemory(@GetFileDateResult, SizeOf(GetFileDateResult));CheckFile := CreateFile('FullPathTo\main.pas', GENERIC_READ, FILE_SHARE_READ, NIL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);如果 CheckFile <>INVALID_HANDLE_VALUE 然后开始如果 GetFileTime(CheckFile, @FileTime, nil, nil) 然后开始如果 FileTimeToLocalFileTime(@FileTime, @FileTimeReturn) 那么开始如果 FileTimeToSystemTime(@FileTimeReturn, @SystemTimeReturn) 那么GetFileDateResult := SystemTimeReturn;结尾;结尾;关闭句柄(检查文件);结尾;GetFileDate := GetFileDateResult;结尾;开始写(GetFileDate.wYear);结尾.
或者,我建议使用 FindFirstFile()
而不是 CreateFile()
,这样您就不必为了获取日期而打开文件.文件系统可以提供该信息,例如:
函数 GetFileDate : SYSTEMTIME;无功检查文件:处理;FindFileData: WIN32_FIND_DATA;文件时间返回:文件时间;SystemTimeReturn: SYSTEMTIME;获取文件日期结果:系统时间;开始ZeroMemory(@GetFileDateResult, SizeOf(GetFileDateResult));CheckFile := FindFirstFile('FullPathTo\main.pas', @FindFileData);如果 CheckFile <>0 那么开始如果 FileTimeToLocalFileTime(@FindFileData.ftCreationTime, @FileTimeReturn) 然后开始如果 FileTimeToSystemTime(@FileTimeReturn, @SystemTimeReturn) 那么GetFileDateResult := SystemTimeReturn;结尾;FindClose(CheckFile);结尾;GetFileDate := GetFileDateResult;结尾;
I'm using the Win32 api to get date and time of a file. I have a LPSYSTEMTIME structure, and I'm trying to print its wYear variable.
I've got a function (GetFileDate):
function GetFileDate : LPSYSTEMTIME
var
CheckFile: Long;
FileTime: LPFILETIME;
FileTimeReturn: LPFILETIME;
SystemTimeReturn: LPSYSTEMTIME;
begin
CheckFile := CreateFile(PChar('main.pas'), GENERIC_READ, FILE_SHARE_READ, NIL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
GetFileTime(CheckFile, FileTime, NIL, NIL);
FileTimeToLocalFileTime(FileTime, FileTimeReturn);
FileTimeToSystemTime(FileTimeReturn, SystemTimeReturn);
GetFileDate := SystemTimeReturn;
end;
But when I do this...
begin
Write(GetFileDate.wYear);
end.
It spits back
main.pas(22,20) Error: Illegal qualifier main.pas(22,20) Fatal: Syntax error, ")" expected but "identifier WYEAR" found Fatal: Compilation aborted
Any help on this?
LPSYSTEMTIME
is a pointer to a SYSTEMTIME
structure. Try using the ^
operator to dereference that pointer, eg:
Write(GetFileDate^.wYear);
Or:
Write(GetFileDate()^.wYear);
With that said, aside from the fact that you are not doing any error handling at all, your GetFileDate()
implementation is passing the wrong parameter values to the various API functions. That code should not even compile, let alone run correctly.
Try this instead:
function GetFileDate : SYSTEMTIME;
var
CheckFile: HANDLE;
FileTime: FILETIME;
FileTimeReturn: FILETIME;
SystemTimeReturn: SYSTEMTIME;
GetFileDateResult: SYSTEMTIME;
begin
ZeroMemory(@GetFileDateResult, SizeOf(GetFileDateResult));
CheckFile := CreateFile('FullPathTo\main.pas', GENERIC_READ, FILE_SHARE_READ, NIL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if CheckFile <> INVALID_HANDLE_VALUE then
begin
if GetFileTime(CheckFile, @FileTime, nil, nil) then
begin
if FileTimeToLocalFileTime(@FileTime, @FileTimeReturn) then
begin
if FileTimeToSystemTime(@FileTimeReturn, @SystemTimeReturn) then
GetFileDateResult := SystemTimeReturn;
end;
end;
CloseHandle(CheckFile);
end;
GetFileDate := GetFileDateResult;
end;
begin
Write(GetFileDate.wYear);
end.
Alternatively, I would suggest using FindFirstFile()
instead of CreateFile()
so you do not have to open the file just to get its date. The filesystem can supply that information, eg:
function GetFileDate : SYSTEMTIME;
var
CheckFile: HANDLE;
FindFileData: WIN32_FIND_DATA;
FileTimeReturn: FILETIME;
SystemTimeReturn: SYSTEMTIME;
GetFileDateResult: SYSTEMTIME;
begin
ZeroMemory(@GetFileDateResult, SizeOf(GetFileDateResult));
CheckFile := FindFirstFile('FullPathTo\main.pas', @FindFileData);
if CheckFile <> 0 then
begin
if FileTimeToLocalFileTime(@FindFileData.ftCreationTime, @FileTimeReturn) then
begin
if FileTimeToSystemTime(@FileTimeReturn, @SystemTimeReturn) then
GetFileDateResult := SystemTimeReturn;
end;
FindClose(CheckFile);
end;
GetFileDate := GetFileDateResult;
end;
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