Mega Code Archive
Files Bigger than 2 gig
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Title: Files Bigger than 2 gig
Question: Searching for files and get no problems when the size is greater than 2 gig
Answer:
The FindFirstFile / FindNextFile / FindClose APIs are used for searching for various files.
When using these APIs it is important to remember that failing to close a Find can result in files or directories not being available for some operations (such as deletes). This is because these APIs open a handle to the objects being searched, and the operating system won't allow you to do certain things to an object as long as an active handle to that object exists.
Also, the data structure used by these APIs contains string data, which is terminated by null characters.
Example:
procedure TForm1.Button1Click(Sender: TObject);
var
Handle:THandle;
s:string;
FD:WIN32_FIND_DATA;
begin
s:='c:\*.*';
Handle:=FindFirstFile(pchar(s), fd);
if HandleINVALID_HANDLE_VALUE then begin
Memo1.Lines.Add(fd.cFileName);
while FindNextFile(handle, fd)=True do
Memo1.Lines.Add(fd.cFileName);
end;
Windows.FindClose(Handle);
end;
Finds the first file matching the wild file specifier. '*' can be used to match 0 or more characters, '?' for a single character. If there are no wild specifiers in the string the function acts as a query for an explicit single file. The function works for both files and folders.
The WIN32_FIND_DATA contains full information about the first matched file.
dwFileAttributes File attributes (see CreateFile)
ftCreationTime Time file created (see GetFileTime)
ftLastAccessTime Time file last accessed
ftLastWriteTime Time file last written to
nFileSizeHigh Most significant 32bits of file size(see GetFileSize)
nFileSizeLow Least significant 32bits of file size
dwReserved0 O.S. specific data
dwReserved1 O.S. specific data
cFileName File name with extension within the folder
cAlternateFileName Alternate shortened (8.3) form of name iff cFileName is not a valid MSDOS name
The returned handle is passed to FindNextFile to get at the next matching file or folder. When the scan is completed FindClose must be used to close the handle.
More Info:
WIN32_FIND_DATA = record
dwFileAttributes: DWORD;
ftCreationTime: TFileTime;
ftLastAccessTime: TFileTime;
ftLastWriteTime: TFileTime;
nFileSizeHigh: DWORD;
nFileSizeLow: DWORD;
dwReserved0: DWORD;
dwReserved1: DWORD;
cFileName: array[0..MAX_PATH - 1] of AnsiChar;
cAlternateFileName: array[0..13] of AnsiChar;
end;
FILE_ATTRIBUTE_ARCHIVE
The file is an archive file. Applications use this value to mark files for backup or removal.
FILE_ATTRIBUTE_COMPRESSED
The file or directory is compressed. For a file, this means that all of the data in the file is compressed. For a directory, this means that compression is the default for newly created files and subdirectories.
FILE_ATTRIBUTE_DIRECTORY
The file is a directory.
FILE_ATTRIBUTE_HIDDEN
The file is hidden. It is not included in an ordinary directory listing.
FILE_ATTRIBUTE_NORMAL
The file has no other attributes set. This value is valid only if used alone.
FILE_ATTRIBUTE_OFFLINE
The data of the file is not immediately available. Indicates that the file data has been physically moved to offline storage.
FILE_ATTRIBUTE_READONLY
The file is read-only. Applications can read the file but cannot write to it or delete it.
FILE_ATTRIBUTE_SYSTEM
The file is part of the operating system or is used exclusively by it.
FILE_ATTRIBUTE_TEMPORARY
The file is being used for temporary storage. Applications should write to the file only if absolutely necessary. Most of the file's data remains in memory without being flushed to the media because the file will soon be deleted.
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