FRead3 Function | |
Read characters from a file into an allocated buffer.
Namespace:
XSharp.Core
Assembly:
XSharp.Core (in XSharp.Core.dll) Version: 2.21
Syntax FUNCTION FRead3(
ptrHandle AS IntPtr,
ptrBufferVar AS BYTE[],
dwBytes AS DWORD
) AS DWORD
public static uint FRead3(
IntPtr ptrHandle,
byte[] ptrBufferVar,
uint dwBytes
)
Request Example
View SourceParameters
- ptrHandle
- Type: IntPtr
The handle of the file to read from. - ptrBufferVar
- Type: Byte
Pointer to an allocated buffer used to store data read from the specified file.
The length of this variable must be greater than or equal to dwBytes.
An array of bytes to store the data read from the specified file. The length of this variable must be greater than or equal to the number of bytes in the next parameter. - dwBytes
- Type: DWord
The number of bytes to read into the buffer.
Return Value
Type:
DWord
The number of bytes successfully read.
A return value less than
dwBytes or 0 indicates end-of-file or some other read error. FError() can be used to determine the specific error.
Remarks
FRead3() is the same as FRead(), except that the name of the buffer variable is a pointer and is not passed by reference.
See FRead() for details.
This function is assumed to handle raw binary data and is not dependent upon the status of SetAnsi(). FReadText() and FRead4(), on the other hand, are dependent upon SetAnsi().
Remarks Tip |
---|
The low level File IO functions in the X# runtime are using .Net filestreams in the background.
That means that the file handles returned by FOpen() and FCreate() are not 'normal' file handles,
but unique identifiers that are used to find the underlying stream object in a collection of
streams in the runtime.
That also means that you can't use file handles for functions such as FRead() and FWrite() that were not
created in the X# runtime.
If you want to access the underlying FileStream, then you should call the
function FGetStream(IntPtr) |
Examples
This example uses FRead3() after successfully opening a file to read 128 bytes into a buffer area:
1DEFINE F_BLOCK := 128
2Function Start()
3 LOCAL cBuffer AS PTR
4 cBuffer := MemAlloc(F_BLOCK)
5 IF cBuffer = NULL PTR
6 RETURN FALSE
7 ENDIF
8 ptrHandle := FOpen2("temp.txt", FO_READ)
9 IF ptrHandle = F_ERROR
10 ? DOSErrString(FError())
11 RETURN FALSE
12 ELSE
13 IF FRead3(ptrHandle, cBuffer, F_BLOCK) <paramref name="" /> F_BLOCK
14 ? DOSErrString(FError())
15 RETURN FALSE
16 ENDIF
17 FClose(ptrHandle)
18 ENDIF
19 MemFree(cBuffer)
20 RETURN TRUE
See Also