FRead Function (IntPtr, Usual, DWord)

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: 2.21

Syntax

 FUNCTION FRead(
	ptrHandle AS IntPtr,
	cBufferVar REF USUAL,
	dwBytes AS DWORD
) AS DWORD

public static uint FRead(
	IntPtr ptrHandle,
	ref Usual cBufferVar,
	uint dwBytes
)

Request Example 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: 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

FReadText() is the same as FRead() except that an OEM to ANSI conversion is made if SetAnsi() is FALSE.

Remarks

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:

Copy

 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) <paramref name="" /> F_BLOCK
 9        ? DOSErrString(FError())
10    ENDIF
11    FClose(ptrHandle)
12ENDIF