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<a name="Increment-Operators"></a>
<h3 class="section">8.7 Increment Operators</h3>
<p><em>Increment operators</em> increase or decrease the value of a variable
by 1. The operator to increment a variable is written as ‘<samp>++</samp>’. It
may be used to increment a variable either before or after taking its
value.
</p>
<p>For example, to pre-increment the variable <var>x</var>, you would write
<code>++<var>x</var></code>. This would add one to <var>x</var> and then return the new
value of <var>x</var> as the result of the expression. It is exactly the
same as the expression <code><var>x</var> = <var>x</var> + 1</code>.
</p>
<p>To post-increment a variable <var>x</var>, you would write <code><var>x</var>++</code>.
This adds one to the variable <var>x</var>, but returns the value that
<var>x</var> had prior to incrementing it. For example, if <var>x</var> is equal
to 2, the result of the expression <code><var>x</var>++</code> is 2, and the new
value of <var>x</var> is 3.
</p>
<p>For matrix and vector arguments, the increment and decrement operators
work on each element of the operand.
</p>
<p>Here is a list of all the increment and decrement expressions.
</p>
<dl compact="compact">
<dt><code>++<var>x</var></code></dt>
<dd><a name="index-_002b_002b"></a>
<p>This expression increments the variable <var>x</var>. The value of the
expression is the <em>new</em> value of <var>x</var>. It is equivalent to the
expression <code><var>x</var> = <var>x</var> + 1</code>.
</p>
</dd>
<dt><code>--<var>x</var></code></dt>
<dd><a name="index-_002d_002d"></a>
<p>This expression decrements the variable <var>x</var>. The value of the
expression is the <em>new</em> value of <var>x</var>. It is equivalent to the
expression <code><var>x</var> = <var>x</var> - 1</code>.
</p>
</dd>
<dt><code><var>x</var>++</code></dt>
<dd><a name="index-_002b_002b-1"></a>
<p>This expression causes the variable <var>x</var> to be incremented. The
value of the expression is the <em>old</em> value of <var>x</var>.
</p>
</dd>
<dt><code><var>x</var>--</code></dt>
<dd><a name="index-_002d_002d-1"></a>
<p>This expression causes the variable <var>x</var> to be decremented. The
value of the expression is the <em>old</em> value of <var>x</var>.
</p></dd>
</dl>
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