arithmetic.xml

<?xml version="1.0" encoding="utf-8"?>
<sect1 xml:id="language.operators.arithmetic">
 <title>Arithmetic Operators</title>
 <titleabbrev>Arithmetic</titleabbrev>
 <simpara>
  Remember basic arithmetic from school? These work just
  like those.
 </simpara>
 <table>
  <title>Arithmetic Operators</title>
  <tgroup cols="3">
   <thead>
    <row>
     <entry>Example</entry>
     <entry>Name</entry>
     <entry>Result</entry>
    </row>
   </thead>
   <tbody>
    <row>
     <entry><code>+$a</code></entry>
     <entry>Identity</entry>
     <entry>
      Conversion of <varname>$a</varname> to <type>int</type> or
      <type>float</type> as appropriate.
     </entry>
    </row>
    <row>
     <entry><code>-$a</code></entry>
     <entry>Negation</entry>
     <entry>Opposite of <varname>$a</varname>.</entry>
    </row>
    <row>
     <entry><code>$a + $b</code></entry>
     <entry>Addition</entry>
     <entry>Sum of <varname>$a</varname> and <varname>$b</varname>.</entry>
    </row>
    <row>
     <entry><code>$a - $b</code></entry>
     <entry>Subtraction</entry>
     <entry>Difference of <varname>$a</varname> and <varname>$b</varname>.</entry>
    </row>
    <row>
     <entry><code>$a * $b</code></entry>
     <entry>Multiplication</entry>
     <entry>Product of <varname>$a</varname> and <varname>$b</varname>.</entry>
    </row>
    <row>
     <entry><code>$a / $b</code></entry>
     <entry>Division</entry>
     <entry>Quotient of <varname>$a</varname> and <varname>$b</varname>.</entry>
    </row>
    <row>
     <entry><code>$a % $b</code></entry>
     <entry>Modulo</entry>
     <entry>Remainder of <varname>$a</varname> divided by <varname>$b</varname>.</entry>
    </row>
    <row>
     <entry><code>$a ** $b</code></entry>
     <entry>Exponentiation</entry>
     <entry>Result of raising <varname>$a</varname> to the <varname>$b</varname>'th power.</entry>
    </row>
   </tbody>
  </tgroup>
 </table>
 <simpara>
  The division operator <literal>/</literal> returns a <type>float</type>
  value unless the two operands are <type>int</type> (or
  <link linkend="language.types.numeric-strings">numeric strings</link>
  which are type juggled to <type>int</type>) and the numerator is a multiple
  of the divisor, in which case an integer value will be returned.
  For integer division, see <function>intdiv</function>.
 </simpara>
 <simpara>
  Operands of modulo are converted to <type>int</type>
  before processing. For floating-point modulo, see
  <function>fmod</function>.
 </simpara>
 <para>
  The result of the modulo operator <literal>%</literal> has the same sign
  as the dividend — that is, the result of <code>$a % $b</code>
  will have the same sign as <varname>$a</varname>. For example:
  <example>
   <title>The Modulo Operator</title>
   <programlisting role="php">
<![CDATA[
<?php
var_dump(5 % 3);
var_dump(5 % -3);
var_dump(-5 % 3);
var_dump(-5 % -3);
?>
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
int(2)
int(2)
int(-2)
int(-2)
]]>
   </screen>
  </example>
 </para>
 <sect2 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><link linkend="ref.math">Math functions</link></member>
   </simplelist>
  </para>
 </sect2>
</sect1>