FUNCTIONUnder review

FREADSTR()

FReadStr( nHandle, nQtdBytes ) --> cRet

Reads up to a byte limit and returns text.

FREADSTR()AdvPL

01 · OVERVIEW

Overview

FReadStr returns a string unlike FRead’s numeric count. It can stop at Chr(0), EOF or error; it is not a generic replacement for binary content requiring preserved null bytes. The GitHub source demonstrates reading through a writable open mode; this adaptation uses read-only access and captures diagnostics before closure. Returned length depends on file and position rather than Unicode character count. (TOTVS, n.d., ref. 1)

02 · SYNTAX

Syntax

FReadStr( nHandle, nQtdBytes ) --> cRet

Parameters

nHandle

NumericRequired

Valid handle from FOpen/FCreate; zero is valid too.

nQtdBytes

NumericRequired

Requested byte limit.

Return value

Text read up to the limit, null or EOF.

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"
#Include "Fileio.ch"

User Function Ed394()
    Local nHandle := -1
    Local nError := 0
    Local cText
    // Pre-existing fictional file in the test context; shared reading.
    nHandle := FOpen("editorial-test.txt", FO_READ + FO_SHARED)
    If nHandle < 0
        nError := FError()
        ConOut(cValToChar(nError))
    Else
        cText := FReadStr(nHandle, 64)
        nError := FError()
        // Report size without exposing file content.
        ConOut(cValToChar(Len(cText)))
        If nError <> 0
            ConOut(cValToChar(nError))
        EndIf
        If !FClose(nHandle)
            ConOut(cValToChar(FError()))
        EndIf
    EndIf
Return Nil

Expected result

Length up to 64 bytes or a diagnostic; content is not shown. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Check path, permissions, platform and handle ownership. Close only handles obtained by this routine, including complete-application error handling.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.