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 <a name="C-Operators"></a>
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 Next:&nbsp;<a rel="next" accesskey="n" href="C-Constants.html#C-Constants">C Constants</a>,
 Up:&nbsp;<a rel="up" accesskey="u" href="C.html#C">C</a>
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 </div>

 <h5 class="subsubsection">15.4.1.1 C and C<tt>++</tt> Operators</h5>

 <p><a name="index-C-and-C_0040t_007b_002b_002b_007d-operators-986"></a>
 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>For the purposes of C and C<tt>++</tt>, the following definitions hold:

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

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

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

    </ul>

 <p class="noindent">The following operators are supported.  They are listed here
 in order of increasing precedence:

      <dl>
 <dt><code>,</code><dd>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.

      <br><dt><code>=</code><dd>Assignment.  The value of an assignment expression is the value
 assigned.  Defined on scalar types.

      <br><dt><var>op</var><code>=</code><dd>Used in an expression of the form <var>a</var><code>&nbsp;</code><var>op</var><code>=&nbsp;</code><var>b</var><!-- /@w -->,
 and translated to <var>a</var><code>&nbsp;=&nbsp;</code><var>a&nbsp;op&nbsp;b</var><!-- /@w -->.
 <var>op</var><code>=</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>.

      <br><dt><code>?:</code><dd>The ternary operator.  <var>a</var><code> ? </code><var>b</var><code> : </code><var>c</var> 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.

      <br><dt><code>||</code><dd>Logical <span class="sc">or</span>.  Defined on integral types.

      <br><dt><code>&amp;&amp;</code><dd>Logical <span class="sc">and</span>.  Defined on integral types.

      <br><dt><code>|</code><dd>Bitwise <span class="sc">or</span>.  Defined on integral types.

      <br><dt><code>^</code><dd>Bitwise exclusive-<span class="sc">or</span>.  Defined on integral types.

      <br><dt><code>&amp;</code><dd>Bitwise <span class="sc">and</span>.  Defined on integral types.

      <br><dt><code>==</code><span class="roman">, </span><code>!=</code><dd>Equality and inequality.  Defined on scalar types.  The value of these
 expressions is 0 for false and non-zero for true.

      <br><dt><code>&lt;</code><span class="roman">, </span><code>&gt;</code><span class="roman">, </span><code>&lt;=</code><span class="roman">, </span><code>&gt;=</code><dd>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.

      <br><dt><code>&lt;&lt;</code><span class="roman">, </span><code>&gt;&gt;</code><dd>left shift, and right shift.  Defined on integral types.

      <br><dt><code>@</code><dd>The <span class="sc">gdb</span> &ldquo;artificial array&rdquo; operator (see <a href="Expressions.html#Expressions">Expressions</a>).

      <br><dt><code>+</code><span class="roman">, </span><code>-</code><dd>Addition and subtraction.  Defined on integral types, floating-point types and
 pointer types.

      <br><dt><code>*</code><span class="roman">, </span><code>/</code><span class="roman">, </span><code>%</code><dd>Multiplication, division, and modulus.  Multiplication and division are
 defined on integral and floating-point types.  Modulus is defined on
 integral types.

      <br><dt><code>++</code><span class="roman">, </span><code>--</code><dd>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.

      <br><dt><code>*</code><dd>Pointer dereferencing.  Defined on pointer types.  Same precedence as
 <code>++</code>.

      <br><dt><code>&amp;</code><dd>Address operator.  Defined on variables.  Same precedence as <code>++</code>.

      <p>For debugging C<tt>++</tt>, <span class="sc">gdb</span> implements a use of &lsquo;<samp><span class="samp">&amp;</span></samp>&rsquo; beyond what is
 allowed in the C<tt>++</tt> language itself: you can use &lsquo;<samp><span class="samp">&amp;(&amp;</span><var>ref</var><span class="samp">)</span></samp>&rsquo;
 to examine the address
 where a C<tt>++</tt> reference variable (declared with &lsquo;<samp><span class="samp">&amp;</span><var>ref</var></samp>&rsquo;) is
 stored.

      <br><dt><code>-</code><dd>Negative.  Defined on integral and floating-point types.  Same
 precedence as <code>++</code>.

      <br><dt><code>!</code><dd>Logical negation.  Defined on integral types.  Same precedence as
 <code>++</code>.

      <br><dt><code>~</code><dd>Bitwise complement operator.  Defined on integral types.  Same precedence as
 <code>++</code>.

      <br><dt><code>.</code><span class="roman">, </span><code>-&gt;</code><dd>Structure member, and pointer-to-structure member.  For convenience,
 <span class="sc">gdb</span> 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.

      <br><dt><code>.*</code><span class="roman">, </span><code>-&gt;*</code><dd>Dereferences of pointers to members.

      <br><dt><code>[]</code><dd>Array indexing.  <var>a</var><code>[</code><var>i</var><code>]</code> is defined as
 <code>*(</code><var>a</var><code>+</code><var>i</var><code>)</code>.  Same precedence as <code>-&gt;</code>.

      <br><dt><code>()</code><dd>Function parameter list.  Same precedence as <code>-&gt;</code>.

      <br><dt><code>::</code><dd>C<tt>++</tt> scope resolution operator.  Defined on <code>struct</code>, <code>union</code>,
 and <code>class</code> types.

      <br><dt><code>::</code><dd>Doubled colons also represent the <span class="sc">gdb</span> scope operator
 (see <a href="Expressions.html#Expressions">Expressions</a>).  Same precedence as <code>::</code>,
 above.
 </dl>

    <p>If an operator is redefined in the user code, <span class="sc">gdb</span> usually
 attempts to invoke the redefined version instead of using the operator's
 predefined meaning.

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	Up: <a rel="up" accesskey="u" href="C.html#C">C</a>
	<hr>
	</div>

	<h5 class="subsubsection">15.4.1.1 C and C<tt>++</tt> Operators</h5>

	<p><a name="index-C-and-C_0040t_007b_002b_002b_007d-operators-986"></a>
	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>For the purposes of C and C<tt>++</tt>, the following definitions hold:

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

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

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

	</ul>

	<p class="noindent">The following operators are supported. They are listed here
	in order of increasing precedence:

	<dl>
	<dt><code>,</code><dd>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.

	<br><dt><code>=</code><dd>Assignment. The value of an assignment expression is the value
	assigned. Defined on scalar types.

	<br><dt><var>op</var><code>=</code><dd>Used in an expression of the form <var>a</var><code> </code><var>op</var><code>= </code><var>b</var><!-- /@w -->,
	and translated to <var>a</var><code> = </code><var>a op b</var><!-- /@w -->.
	<var>op</var><code>=</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>.

	<br><dt><code>?:</code><dd>The ternary operator. <var>a</var><code> ? </code><var>b</var><code> : </code><var>c</var> 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.

	<br><dt><code>\|\|</code><dd>Logical <span class="sc">or</span>. Defined on integral types.

	<br><dt><code>&&</code><dd>Logical <span class="sc">and</span>. Defined on integral types.

	<br><dt><code>\|</code><dd>Bitwise <span class="sc">or</span>. Defined on integral types.

	<br><dt><code>^</code><dd>Bitwise exclusive-<span class="sc">or</span>. Defined on integral types.

	<br><dt><code>&</code><dd>Bitwise <span class="sc">and</span>. Defined on integral types.

	<br><dt><code>==</code><span class="roman">, </span><code>!=</code><dd>Equality and inequality. Defined on scalar types. The value of these
	expressions is 0 for false and non-zero for true.

	<br><dt><code><</code><span class="roman">, </span><code>></code><span class="roman">, </span><code><=</code><span class="roman">, </span><code>>=</code><dd>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.

	<br><dt><code><<</code><span class="roman">, </span><code>>></code><dd>left shift, and right shift. Defined on integral types.

	<br><dt><code>@</code><dd>The <span class="sc">gdb</span> “artificial array” operator (see <a href="Expressions.html#Expressions">Expressions</a>).

	<br><dt><code>+</code><span class="roman">, </span><code>-</code><dd>Addition and subtraction. Defined on integral types, floating-point types and
	pointer types.

	<br><dt><code>*</code><span class="roman">, </span><code>/</code><span class="roman">, </span><code>%</code><dd>Multiplication, division, and modulus. Multiplication and division are
	defined on integral and floating-point types. Modulus is defined on
	integral types.

	<br><dt><code>++</code><span class="roman">, </span><code>--</code><dd>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.

	<br><dt><code>*</code><dd>Pointer dereferencing. Defined on pointer types. Same precedence as
	<code>++</code>.

	<br><dt><code>&</code><dd>Address operator. Defined on variables. Same precedence as <code>++</code>.

	<p>For debugging C<tt>++</tt>, <span class="sc">gdb</span> implements a use of ‘<samp><span class="samp">&</span></samp>’ beyond what is
	allowed in the C<tt>++</tt> language itself: you can use ‘<samp><span class="samp">&(&</span><var>ref</var><span class="samp">)</span></samp>’
	to examine the address
	where a C<tt>++</tt> reference variable (declared with ‘<samp><span class="samp">&</span><var>ref</var></samp>’) is
	stored.

	<br><dt><code>-</code><dd>Negative. Defined on integral and floating-point types. Same
	precedence as <code>++</code>.

	<br><dt><code>!</code><dd>Logical negation. Defined on integral types. Same precedence as
	<code>++</code>.

	<br><dt><code>~</code><dd>Bitwise complement operator. Defined on integral types. Same precedence as
	<code>++</code>.

	<br><dt><code>.</code><span class="roman">, </span><code>-></code><dd>Structure member, and pointer-to-structure member. For convenience,
	<span class="sc">gdb</span> 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.

	<br><dt><code>.</code><span class="roman">, </span><code>-></code><dd>Dereferences of pointers to members.

	<br><dt><code>[]</code><dd>Array indexing. <var>a</var><code>[</code><var>i</var><code>]</code> is defined as
	<code>*(</code><var>a</var><code>+</code><var>i</var><code>)</code>. Same precedence as <code>-></code>.

	<br><dt><code>()</code><dd>Function parameter list. Same precedence as <code>-></code>.

	<br><dt><code>::</code><dd>C<tt>++</tt> scope resolution operator. Defined on <code>struct</code>, <code>union</code>,
	and <code>class</code> types.

	<br><dt><code>::</code><dd>Doubled colons also represent the <span class="sc">gdb</span> scope operator
	(see <a href="Expressions.html#Expressions">Expressions</a>). Same precedence as <code>::</code>,
	above.
	</dl>

	<p>If an operator is redefined in the user code, <span class="sc">gdb</span> usually
	attempts to invoke the redefined version instead of using the operator's
	predefined meaning.

	</body></html>