<?xml version="1.0" encoding="utf-8"?>+
−
<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->+
−
<!-- This component and the accompanying materials are made available under the terms of the License +
−
"Eclipse Public License v1.0" which accompanies this distribution, +
−
and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->+
−
<!-- Initial Contributors:+
−
    Nokia Corporation - initial contribution.+
−
Contributors: +
−
-->+
−
<!DOCTYPE concept+
−
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">+
−
<concept id="GUID-189FBB0E-0A47-5CCC-9209-DC69E76DE6B3" xml:lang="en"><title>Boolean</title><shortdesc>This document describes the Boolean data types.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>+
−
<p><xref href="GUID-4B942C06-1BAC-3A21-B3B1-89FB5C51ADA0.dita"><apiname>TBool</apiname></xref> represents a Boolean whose value may be <codeph>ETrue</codeph> or <codeph>EFalse</codeph>.+
−
It is implemented as a natural machine-word integer.</p>+
−
<p>The C language defines logical expressions to <i>produce</i> 0 for false,+
−
1 for true, and to <i>interpret</i> 0 as false, non-zero as true. This confusion+
−
cannot be altogether avoided with <codeph>TBool</codeph>. It is possible,+
−
but strongly deprecated, to assign numeric values to a <xref href="GUID-4B942C06-1BAC-3A21-B3B1-89FB5C51ADA0.dita"><apiname>TBool</apiname></xref>.</p>+
−
<p>In general, a <xref href="GUID-4B942C06-1BAC-3A21-B3B1-89FB5C51ADA0.dita"><apiname>TBool</apiname></xref> should be tested using</p>+
−
<codeblock id="GUID-BF6AF640-D03A-5335-B67B-3852C2808833" xml:space="preserve">if (x) ...</codeblock>+
−
<p>or</p>+
−
<codeblock id="GUID-D00FBCFD-57C2-5D1E-999A-0567AFBAA258" xml:space="preserve">if (!x) ...</codeblock>+
−
<p>rather than</p>+
−
<codeblock id="GUID-41D4B777-217D-5BA5-B44A-59C2419FB2D6" xml:space="preserve">if (x==ETrue) ...</codeblock>+
−
<p>or</p>+
−
<codeblock id="GUID-72F416BC-213F-5731-B26A-8ECE2916935B" xml:space="preserve">if (x==EFalse) ...</codeblock>+
−
<p>The <xref href="GUID-4B942C06-1BAC-3A21-B3B1-89FB5C51ADA0.dita"><apiname>TBool</apiname></xref> uses a whole machine word. When a class has+
−
a number of flags, they should be encoded in a flags byte, and suitable getter/setter+
−
functions, taking <xref href="GUID-4B942C06-1BAC-3A21-B3B1-89FB5C51ADA0.dita"><apiname>TBool</apiname></xref> s, should be coded to access that+
−
flags byte.</p>+
−
</conbody></concept>+
−