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FRead Function (IntPtr, Usual, UInt32)

Read characters from a file into a buffer variable that is passed by reference.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.4a
Syntax
 FUNCTION FRead(
	ptrHandle AS IntPtr,
	cBufferVar REF USUAL,
	dwBytes AS DWORD
) AS DWORD
View Source

Parameters

ptrHandle
Type: IntPtr
The handle of the file to read from.
cBufferVar
Type: Usual
A variable used to store data read from the specified file.
If the length of <cBufferVar> is less than <dwBytes>, a new string whose length is the minimum of <dwBytes> and the remaining bytes in the file is allocated.  <cBufferVar> must be passed by reference and, therefore, must be prefaced by the pass-by-reference operator (@).
dwBytes
Type: UInt32
The number of bytes to read into the buffer.

Return Value

Type: UInt32
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
FReadText() is the same as FRead() except that an OEM to ANSI conversion is made if SetAnsi() is FALSE.
Remarks
Tip Tip
This function is included for compatibility. We do not recomment using static memory for file i/o operations. We recommend that you use the function overload that takes a byte array parameter in stead.
Examples
This example uses FRead() after successfully opening a file to read 128 bytes into a buffer area:
X#
 1DEFINE F_BLOCK := 128
 2...
 3cBuffer := Space(F_BLOCK)
 4ptrHandle := FOpen("temp.txt")
 5IF FError() != 0
 6    ? DOSErrString(FError())
 7ELSE
 8    IF FReadText(ptrHandle, @cBuffer, F_BLOCK) <> F_BLOCK
 9        ? DOSErrString(FError())
10    ENDIF
11    FClose(ptrHandle)
12ENDIF
See Also