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 <a name="C-Operators"></a>
 <div class="header">
 <p>
 Next: <a href="C-Constants.html#C-Constants" accesskey="n" rel="next">C Constants</a>, Up: <a href="C.html#C" accesskey="u" rel="up">C</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
 </div>
 <hr>
 <a name="C-and-C_002b_002b-Operators"></a>
 <h4 class="subsubsection">15.4.1.1 C and C<tt>++</tt> Operators</h4>

 <a name="index-C-and-C_002b_002b-operators"></a>

 <p>Operators must be defined on values of specific types.  For instance,
 <code>+</code> is defined on numbers, but not on structures.  Operators are
 often defined on groups of types.
 </p>
 <p>For the purposes of C and C<tt>++</tt>, the following definitions hold:
 </p>
 <ul>
 <li> <em>Integral types</em> include <code>int</code> with any of its storage-class
 specifiers; <code>char</code>; <code>enum</code>; and, for C<tt>++</tt>, <code>bool</code>.

 </li><li> <em>Floating-point types</em> include <code>float</code>, <code>double</code>, and
 <code>long double</code> (if supported by the target platform).

 </li><li> <em>Pointer types</em> include all types defined as <code>(<var>type</var> *)</code>.

 </li><li> <em>Scalar types</em> include all of the above.

 </li></ul>

 <p>The following operators are supported.  They are listed here
 in order of increasing precedence:
 </p>
 <dl compact="compact">
 <dt><code>,</code></dt>
 <dd><p>The comma or sequencing operator.  Expressions in a comma-separated list
 are evaluated from left to right, with the result of the entire
 expression being the last expression evaluated.
 </p>
 </dd>
 <dt><code>=</code></dt>
 <dd><p>Assignment.  The value of an assignment expression is the value
 assigned.  Defined on scalar types.
 </p>
 </dd>
 <dt><code><var>op</var>=</code></dt>
 <dd><p>Used in an expression of the form <code><var>a</var>&nbsp;<var>op</var>=&nbsp;<var>b</var></code><!-- /@w -->,
 and translated to <code><var>a</var>&nbsp;=&nbsp;<var>a&nbsp;op&nbsp;b</var></code><!-- /@w -->.
 <code><var>op</var>=</code><!-- /@w --> and <code>=</code> have the same precedence.  The operator
 <var>op</var> is any one of the operators <code>|</code>, <code>^</code>, <code>&amp;</code>,
 <code>&lt;&lt;</code>, <code>&gt;&gt;</code>, <code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>, <code>%</code>.
 </p>
 </dd>
 <dt><code>?:</code></dt>
 <dd><p>The ternary operator.  <code><var>a</var> ? <var>b</var> : <var>c</var></code> can be thought
 of as:  if <var>a</var> then <var>b</var> else <var>c</var>.  The argument <var>a</var>
 should be of an integral type.
 </p>
 </dd>
 <dt><code>||</code></dt>
 <dd><p>Logical <small>OR</small>.  Defined on integral types.
 </p>
 </dd>
 <dt><code>&amp;&amp;</code></dt>
 <dd><p>Logical <small>AND</small>.  Defined on integral types.
 </p>
 </dd>
 <dt><code>|</code></dt>
 <dd><p>Bitwise <small>OR</small>.  Defined on integral types.
 </p>
 </dd>
 <dt><code>^</code></dt>
 <dd><p>Bitwise exclusive-<small>OR</small>.  Defined on integral types.
 </p>
 </dd>
 <dt><code>&amp;</code></dt>
 <dd><p>Bitwise <small>AND</small>.  Defined on integral types.
 </p>
 </dd>
 <dt><code>==<span class="roman">, </span>!=</code></dt>
 <dd><p>Equality and inequality.  Defined on scalar types.  The value of these
 expressions is 0 for false and non-zero for true.
 </p>
 </dd>
 <dt><code>&lt;<span class="roman">, </span>&gt;<span class="roman">, </span>&lt;=<span class="roman">, </span>&gt;=</code></dt>
 <dd><p>Less than, greater than, less than or equal, greater than or equal.
 Defined on scalar types.  The value of these expressions is 0 for false
 and non-zero for true.
 </p>
 </dd>
 <dt><code>&lt;&lt;<span class="roman">, </span>&gt;&gt;</code></dt>
 <dd><p>left shift, and right shift.  Defined on integral types.
 </p>
 </dd>
 <dt><code>@</code></dt>
 <dd><p>The <small>GDB</small> &ldquo;artificial array&rdquo; operator (see <a href="Expressions.html#Expressions">Expressions</a>).
 </p>
 </dd>
 <dt><code>+<span class="roman">, </span>-</code></dt>
 <dd><p>Addition and subtraction.  Defined on integral types, floating-point types and
 pointer types.
 </p>
 </dd>
 <dt><code>*<span class="roman">, </span>/<span class="roman">, </span>%</code></dt>
 <dd><p>Multiplication, division, and modulus.  Multiplication and division are
 defined on integral and floating-point types.  Modulus is defined on
 integral types.
 </p>
 </dd>
 <dt><code>++<span class="roman">, </span>--</code></dt>
 <dd><p>Increment and decrement.  When appearing before a variable, the
 operation is performed before the variable is used in an expression;
 when appearing after it, the variable&rsquo;s value is used before the
 operation takes place.
 </p>
 </dd>
 <dt><code>*</code></dt>
 <dd><p>Pointer dereferencing.  Defined on pointer types.  Same precedence as
 <code>++</code>.
 </p>
 </dd>
 <dt><code>&amp;</code></dt>
 <dd><p>Address operator.  Defined on variables.  Same precedence as <code>++</code>.
 </p>
 <p>For debugging C<tt>++</tt>, <small>GDB</small> implements a use of &lsquo;<samp>&amp;</samp>&rsquo; beyond what is
 allowed in the C<tt>++</tt> language itself: you can use &lsquo;<samp>&amp;(&amp;<var>ref</var>)</samp>&rsquo;
 to examine the address
 where a C<tt>++</tt> reference variable (declared with &lsquo;<samp>&amp;<var>ref</var></samp>&rsquo;) is
 stored.
 </p>
 </dd>
 <dt><code>-</code></dt>
 <dd><p>Negative.  Defined on integral and floating-point types.  Same
 precedence as <code>++</code>.
 </p>
 </dd>
 <dt><code>!</code></dt>
 <dd><p>Logical negation.  Defined on integral types.  Same precedence as
 <code>++</code>.
 </p>
 </dd>
 <dt><code>~</code></dt>
 <dd><p>Bitwise complement operator.  Defined on integral types.  Same precedence as
 <code>++</code>.
 </p>

 </dd>
 <dt><code>.<span class="roman">, </span>-&gt;</code></dt>
 <dd><p>Structure member, and pointer-to-structure member.  For convenience,
 <small>GDB</small> regards the two as equivalent, choosing whether to dereference a
 pointer based on the stored type information.
 Defined on <code>struct</code> and <code>union</code> data.
 </p>
 </dd>
 <dt><code>.*<span class="roman">, </span>-&gt;*</code></dt>
 <dd><p>Dereferences of pointers to members.
 </p>
 </dd>
 <dt><code>[]</code></dt>
 <dd><p>Array indexing.  <code><var>a</var>[<var>i</var>]</code> is defined as
 <code>*(<var>a</var>+<var>i</var>)</code>.  Same precedence as <code>-&gt;</code>.
 </p>
 </dd>
 <dt><code>()</code></dt>
 <dd><p>Function parameter list.  Same precedence as <code>-&gt;</code>.
 </p>
 </dd>
 <dt><code>::</code></dt>
 <dd><p>C<tt>++</tt> scope resolution operator.  Defined on <code>struct</code>, <code>union</code>,
 and <code>class</code> types.
 </p>
 </dd>
 <dt><code>::</code></dt>
 <dd><p>Doubled colons also represent the <small>GDB</small> scope operator
 (see <a href="Expressions.html#Expressions">Expressions</a>).  Same precedence as <code>::</code>,
 above.
 </p></dd>
 </dl>

 <p>If an operator is redefined in the user code, <small>GDB</small> usually
 attempts to invoke the redefined version instead of using the operator&rsquo;s
 predefined meaning.
 </p>
 <hr>
 <div class="header">
 <p>
 Next: <a href="C-Constants.html#C-Constants" accesskey="n" rel="next">C Constants</a>, Up: <a href="C.html#C" accesskey="u" rel="up">C</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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	<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
	<a name="C-Operators"></a>
	<div class="header">
	<p>
	Next: <a href="C-Constants.html#C-Constants" accesskey="n" rel="next">C Constants</a>, Up: <a href="C.html#C" accesskey="u" rel="up">C</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
	</div>
	<hr>
	<a name="C-and-C_002b_002b-Operators"></a>
	<h4 class="subsubsection">15.4.1.1 C and C<tt>++</tt> Operators</h4>

	<a name="index-C-and-C_002b_002b-operators"></a>

	<p>Operators must be defined on values of specific types. For instance,
	<code>+</code> is defined on numbers, but not on structures. Operators are
	often defined on groups of types.
	</p>
	<p>For the purposes of C and C<tt>++</tt>, the following definitions hold:
	</p>
	<ul>
	<li> <em>Integral types</em> include <code>int</code> with any of its storage-class
	specifiers; <code>char</code>; <code>enum</code>; and, for C<tt>++</tt>, <code>bool</code>.

	</li><li> <em>Floating-point types</em> include <code>float</code>, <code>double</code>, and
	<code>long double</code> (if supported by the target platform).

	</li><li> <em>Pointer types</em> include all types defined as <code>(<var>type</var> *)</code>.

	</li><li> <em>Scalar types</em> include all of the above.

	</li></ul>

	<p>The following operators are supported. They are listed here
	in order of increasing precedence:
	</p>
	<dl compact="compact">
	<dt><code>,</code></dt>
	<dd><p>The comma or sequencing operator. Expressions in a comma-separated list
	are evaluated from left to right, with the result of the entire
	expression being the last expression evaluated.
	</p>
	</dd>
	<dt><code>=</code></dt>
	<dd><p>Assignment. The value of an assignment expression is the value
	assigned. Defined on scalar types.
	</p>
	</dd>
	<dt><code><var>op</var>=</code></dt>
	<dd><p>Used in an expression of the form <code><var>a</var> <var>op</var>= <var>b</var></code><!-- /@w -->,
	and translated to <code><var>a</var> = <var>a op b</var></code><!-- /@w -->.
	<code><var>op</var>=</code><!-- /@w --> and <code>=</code> have the same precedence. The operator
	<var>op</var> is any one of the operators <code>\|</code>, <code>^</code>, <code>&</code>,
	<code><<</code>, <code>>></code>, <code>+</code>, <code>-</code>, <code>*</code>, <code>/</code>, <code>%</code>.
	</p>
	</dd>
	<dt><code>?:</code></dt>
	<dd><p>The ternary operator. <code><var>a</var> ? <var>b</var> : <var>c</var></code> can be thought
	of as: if <var>a</var> then <var>b</var> else <var>c</var>. The argument <var>a</var>
	should be of an integral type.
	</p>
	</dd>
	<dt><code>\|\|</code></dt>
	<dd><p>Logical <small>OR</small>. Defined on integral types.
	</p>
	</dd>
	<dt><code>&&</code></dt>
	<dd><p>Logical <small>AND</small>. Defined on integral types.
	</p>
	</dd>
	<dt><code>\|</code></dt>
	<dd><p>Bitwise <small>OR</small>. Defined on integral types.
	</p>
	</dd>
	<dt><code>^</code></dt>
	<dd><p>Bitwise exclusive-<small>OR</small>. Defined on integral types.
	</p>
	</dd>
	<dt><code>&</code></dt>
	<dd><p>Bitwise <small>AND</small>. Defined on integral types.
	</p>
	</dd>
	<dt><code>==<span class="roman">, </span>!=</code></dt>
	<dd><p>Equality and inequality. Defined on scalar types. The value of these
	expressions is 0 for false and non-zero for true.
	</p>
	</dd>
	<dt><code><<span class="roman">, </span>><span class="roman">, </span><=<span class="roman">, </span>>=</code></dt>
	<dd><p>Less than, greater than, less than or equal, greater than or equal.
	Defined on scalar types. The value of these expressions is 0 for false
	and non-zero for true.
	</p>
	</dd>
	<dt><code><<<span class="roman">, </span>>></code></dt>
	<dd><p>left shift, and right shift. Defined on integral types.
	</p>
	</dd>
	<dt><code>@</code></dt>
	<dd><p>The <small>GDB</small> “artificial array” operator (see <a href="Expressions.html#Expressions">Expressions</a>).
	</p>
	</dd>
	<dt><code>+<span class="roman">, </span>-</code></dt>
	<dd><p>Addition and subtraction. Defined on integral types, floating-point types and
	pointer types.
	</p>
	</dd>
	<dt><code>*<span class="roman">, </span>/<span class="roman">, </span>%</code></dt>
	<dd><p>Multiplication, division, and modulus. Multiplication and division are
	defined on integral and floating-point types. Modulus is defined on
	integral types.
	</p>
	</dd>
	<dt><code>++<span class="roman">, </span>--</code></dt>
	<dd><p>Increment and decrement. When appearing before a variable, the
	operation is performed before the variable is used in an expression;
	when appearing after it, the variable’s value is used before the
	operation takes place.
	</p>
	</dd>
	<dt><code>*</code></dt>
	<dd><p>Pointer dereferencing. Defined on pointer types. Same precedence as
	<code>++</code>.
	</p>
	</dd>
	<dt><code>&</code></dt>
	<dd><p>Address operator. Defined on variables. Same precedence as <code>++</code>.
	</p>
	<p>For debugging C<tt>++</tt>, <small>GDB</small> implements a use of ‘<samp>&</samp>’ beyond what is
	allowed in the C<tt>++</tt> language itself: you can use ‘<samp>&(&<var>ref</var>)</samp>’
	to examine the address
	where a C<tt>++</tt> reference variable (declared with ‘<samp>&<var>ref</var></samp>’) is
	stored.
	</p>
	</dd>
	<dt><code>-</code></dt>
	<dd><p>Negative. Defined on integral and floating-point types. Same
	precedence as <code>++</code>.
	</p>
	</dd>
	<dt><code>!</code></dt>
	<dd><p>Logical negation. Defined on integral types. Same precedence as
	<code>++</code>.
	</p>
	</dd>
	<dt><code>~</code></dt>
	<dd><p>Bitwise complement operator. Defined on integral types. Same precedence as
	<code>++</code>.
	</p>

	</dd>
	<dt><code>.<span class="roman">, </span>-></code></dt>
	<dd><p>Structure member, and pointer-to-structure member. For convenience,
	<small>GDB</small> regards the two as equivalent, choosing whether to dereference a
	pointer based on the stored type information.
	Defined on <code>struct</code> and <code>union</code> data.
	</p>
	</dd>
	<dt><code>.<span class="roman">, </span>-></code></dt>
	<dd><p>Dereferences of pointers to members.
	</p>
	</dd>
	<dt><code>[]</code></dt>
	<dd><p>Array indexing. <code><var>a</var>[<var>i</var>]</code> is defined as
	<code>*(<var>a</var>+<var>i</var>)</code>. Same precedence as <code>-></code>.
	</p>
	</dd>
	<dt><code>()</code></dt>
	<dd><p>Function parameter list. Same precedence as <code>-></code>.
	</p>
	</dd>
	<dt><code>::</code></dt>
	<dd><p>C<tt>++</tt> scope resolution operator. Defined on <code>struct</code>, <code>union</code>,
	and <code>class</code> types.
	</p>
	</dd>
	<dt><code>::</code></dt>
	<dd><p>Doubled colons also represent the <small>GDB</small> scope operator
	(see <a href="Expressions.html#Expressions">Expressions</a>). Same precedence as <code>::</code>,
	above.
	</p></dd>
	</dl>

	<p>If an operator is redefined in the user code, <small>GDB</small> usually
	attempts to invoke the redefined version instead of using the operator’s
	predefined meaning.
	</p>
	<hr>
	<div class="header">
	<p>
	Next: <a href="C-Constants.html#C-Constants" accesskey="n" rel="next">C Constants</a>, Up: <a href="C.html#C" accesskey="u" rel="up">C</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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