📄 static-definitions.html
字号:
<html lang="en">
<head>
<title>Using the GNU Compiler Collection (GCC)</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using the GNU Compiler Collection (GCC)">
<meta name="generator" content="makeinfo 4.3">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home">
<!--
Copyright © 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "GNU General Public License" and "Funding
Free Software", the Front-Cover texts being (a) (see below), and with
the Back-Cover Texts being (b) (see below). A copy of the license is
included in the section entitled "GNU Free Documentation License".
<p>(a) The FSF's Front-Cover Text is:
<p>A GNU Manual
<p>(b) The FSF's Back-Cover Text is:
<p>You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.-->
</head>
<body>
<div class="node">
<p>
Node:<a name="Static%20Definitions">Static Definitions</a>,
Next:<a rel="next" accesskey="n" href="Temporaries.html#Temporaries">Temporaries</a>,
Up:<a rel="up" accesskey="u" href="C---Misunderstandings.html#C++%20Misunderstandings">C++ Misunderstandings</a>
<hr><br>
</div>
<h4 class="subsection">Declare <em>and</em> Define Static Members</h4>
<p>When a class has static data members, it is not enough to <em>declare</em>
the static member; you must also <em>define</em> it. For example:
<pre class="example"> class Foo
{
...
void method();
static int bar;
};
</pre>
<p>This declaration only establishes that the class <code>Foo</code> has an
<code>int</code> named <code>Foo::bar</code>, and a member function named
<code>Foo::method</code>. But you still need to define <em>both</em>
<code>method</code> and <code>bar</code> elsewhere. According to the ISO
standard, you must supply an initializer in one (and only one) source
file, such as:
<pre class="example"> int Foo::bar = 0;
</pre>
<p>Other C++ compilers may not correctly implement the standard behavior.
As a result, when you switch to <code>g++</code> from one of these compilers,
you may discover that a program that appeared to work correctly in fact
does not conform to the standard: <code>g++</code> reports as undefined
symbols any static data members that lack definitions.
</body></html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -