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<concept id="GUID-6C1E4B3D-0FBF-5CEA-9A30-B4C5CB4CAC3E" xml:lang="en"><title>Coding

literal descriptors</title><shortdesc>Literal descriptors must be defined in their own C++ statement

and the resulting constant used wherever it is required.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p> Literal descriptors cannot be embedded in expressions because they do

not create temporary objects.</p>

<p>Literal objects can be declared safely in header files:</p>

<ul>

<li id="GUID-1EEAF77A-63B1-5191-95D7-6F24FAC6B94C"><p>without requiring writable

data</p> </li>

<li id="GUID-BED08A91-2EAF-53CB-9B23-8F63D5658303"><p>without creating a copy

of the data in every module that includes the header.</p> </li>

</ul>

<p>Literals can be defined at file-scope, including in header files, in which

case they are visible to any code that follows. They can also be declared

local to the function which uses them. However, there are a couple of caveats

with defining them at function scope:</p>

<ul>

<li id="GUID-9193E180-8358-5BB9-8A76-5EAB4753FB4E"><p>For very short strings,

of the order of 3 ASCII characters or 1 UNICODE character, it is more efficient

to declare the literals at file scope.</p> </li>

<li id="GUID-CAEF761B-7E05-58C7-968E-FF9C31413FFB"><p>Literal descriptors

defined in inline functions are laid down in <i>every single</i> compilation

module that includes the header file.</p> </li>

</ul>

<p>Thus, if the descriptor is short or used only in an inline function, it

is better to define it at file scope with a suitably distinct name.</p>