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https://github.com/sigmasternchen/php-doc-en
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1ef2fdddac
Added more information to the return value of the function. Added a specific example demonstrating various precision on a float. Improved other examples. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@347481 c90b9560-bf6c-de11-be94-00142212c4b1
367 lines
9.7 KiB
XML
367 lines
9.7 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.round" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>round</refname>
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<refpurpose>Rounds a float</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>float</type><methodname>round</methodname>
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<methodparam><type>float</type><parameter>val</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>precision</parameter><initializer>0</initializer></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>mode</parameter><initializer>PHP_ROUND_HALF_UP</initializer></methodparam>
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</methodsynopsis>
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<para>
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Returns the rounded value of <parameter>val</parameter> to
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specified <parameter>precision</parameter>
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(number of digits after the decimal point).
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<parameter>precision</parameter> can also be negative or zero (default).
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</para>
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<!-- It's not true
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<para>
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<caution>
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<simpara>
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When rounding on exact halves <function>round</function> rounds down on
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evens and up on odds. If you want to always force it in one direction
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on a .5 (or .05 in your case) add or subtract a tiny fuzz factor. The
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reason behind rounding half the values down and the other half up is to
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avoid the classical banking problem where if you always rounded down
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you would be stealing money from your customers, or if you always
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rounded up you would end up over time losing money. By averaging it
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out through evens and odds you statistically break even.
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</simpara>
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</caution>
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</para>
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-->
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<para>
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<note>
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<simpara>
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PHP doesn't handle strings like <literal>"12,300.2"</literal> correctly
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by default. See <link linkend="language.types.string.conversion"
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>converting from strings</link>.
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</simpara>
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</note>
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>val</parameter></term>
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<listitem>
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<para>
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The value to round.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>precision</parameter></term>
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<listitem>
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<para>
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The optional number of decimal digits to round to.
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</para>
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<para>
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If the <parameter>precision</parameter> is positive,
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the rounding will occur after the decimal point.
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</para>
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<para>
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If the <parameter>precision</parameter> is negative,
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the rounding will occur before the decimal point.
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If the absolute value of the <parameter>precision</parameter>
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is greater than or equal to the number of digits, the result
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of the rounding is equal to <literal>0</literal>
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>mode</parameter></term>
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<listitem>
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<para>
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Use one of the following constants to specify the mode in which rounding occurs.
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Constants;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><constant>PHP_ROUND_HALF_UP</constant></entry>
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<entry>
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Round <parameter>val</parameter> up to <parameter>precision</parameter> decimal places
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away from zero, when it is half way there. Making 1.5 into 2 and -1.5 into -2.
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</entry>
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</row>
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<row>
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<entry><constant>PHP_ROUND_HALF_DOWN</constant></entry>
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<entry>
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Round <parameter>val</parameter> down to <parameter>precision</parameter> decimal places
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towards zero, when it is half way there. Making 1.5 into 1 and -1.5 into -1.
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</entry>
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</row>
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<row>
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<entry><constant>PHP_ROUND_HALF_EVEN</constant></entry>
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<entry>
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Round <parameter>val</parameter> to <parameter>precision</parameter> decimal places
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towards the nearest even value.
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</entry>
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</row>
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<row>
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<entry><constant>PHP_ROUND_HALF_ODD</constant></entry>
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<entry>
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Round <parameter>val</parameter> to <parameter>precision</parameter> decimal places
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towards the nearest odd value.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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The value rounded to the given <parameter>precision</parameter> as a &float;.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>round</function> examples</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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var_dump(round(3.4));
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var_dump(round(3.5));
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var_dump(round(3.6));
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var_dump(round(3.6, 0));
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var_dump(round(1.95583, 2));
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var_dump(round(1241757, -3));
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var_dump(round(5.045, 2));
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var_dump(round(5.055, 2));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen role="php">
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<![CDATA[
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float(3)
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float(4)
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float(4)
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float(4)
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float(1.96)
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float(1242000)
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float(5.05)
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float(5.06)
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title>How <parameter>precision</parameter> affects a float</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$number = 1346.21;
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var_dump(round($number, 2));
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var_dump(round($number, 1));
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var_dump(round($number, 0));
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var_dump(round($number, -1));
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var_dump(round($number, -2));
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var_dump(round($number, -3));
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var_dump(round($number, -4));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen role="php">
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<![CDATA[
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float(1346.21)
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float(1346.2)
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float(1346)
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float(1350)
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float(1300)
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float(1000)
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float(0)
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title><parameter>mode</parameter> examples</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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echo 'Rounding modes with 9.5' . PHP_EOL;
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var_dump(round(9.5, 0, PHP_ROUND_HALF_UP));
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var_dump(round(9.5, 0, PHP_ROUND_HALF_DOWN));
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var_dump(round(9.5, 0, PHP_ROUND_HALF_EVEN));
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var_dump(round(9.5, 0, PHP_ROUND_HALF_ODD));
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echo 'Rounding modes with 8.5' . PHP_EOL;
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var_dump(round(8.5, 0, PHP_ROUND_HALF_UP));
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var_dump(round(8.5, 0, PHP_ROUND_HALF_DOWN));
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var_dump(round(8.5, 0, PHP_ROUND_HALF_EVEN));
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var_dump(round(8.5, 0, PHP_ROUND_HALF_ODD));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen role="php">
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<![CDATA[
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Rounding modes with 9.5
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float(10)
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float(9)
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float(10)
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float(9)
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Rounding modes with 8.5
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float(9)
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float(8)
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float(8)
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float(9)
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]]>
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</screen>
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</example>
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</para>
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<para>
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<example>
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<title><parameter>mode</parameter> with <parameter>precision</parameter> examples</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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echo 'Using PHP_ROUND_HALF_UP with 1 decimal digit precision' . PHP_EOL;
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var_dump(round( 1.55, 1, PHP_ROUND_HALF_UP));
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var_dump(round( 1.54, 1, PHP_ROUND_HALF_UP));
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var_dump(round(-1.55, 1, PHP_ROUND_HALF_UP));
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var_dump(round(-1.54, 1, PHP_ROUND_HALF_UP));
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echo PHP_EOL;
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echo 'Using PHP_ROUND_HALF_DOWN with 1 decimal digit precision' . PHP_EOL;
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var_dump(round( 1.55, 1, PHP_ROUND_HALF_DOWN));
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var_dump(round( 1.54, 1, PHP_ROUND_HALF_DOWN));
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var_dump(round(-1.55, 1, PHP_ROUND_HALF_DOWN));
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var_dump(round(-1.54, 1, PHP_ROUND_HALF_DOWN));
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echo PHP_EOL;
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echo 'Using PHP_ROUND_HALF_EVEN with 1 decimal digit precision' . PHP_EOL;
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var_dump(round( 1.55, 1, PHP_ROUND_HALF_EVEN));
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var_dump(round( 1.54, 1, PHP_ROUND_HALF_EVEN));
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var_dump(round(-1.55, 1, PHP_ROUND_HALF_EVEN));
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var_dump(round(-1.54, 1, PHP_ROUND_HALF_EVEN));
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echo PHP_EOL;
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echo 'Using PHP_ROUND_HALF_ODD with 1 decimal digit precision' . PHP_EOL;
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var_dump(round( 1.55, 1, PHP_ROUND_HALF_ODD));
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var_dump(round( 1.54, 1, PHP_ROUND_HALF_ODD));
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var_dump(round(-1.55, 1, PHP_ROUND_HALF_ODD));
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var_dump(round(-1.54, 1, PHP_ROUND_HALF_ODD));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen role="php">
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<![CDATA[
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Using PHP_ROUND_HALF_UP with 1 decimal digit precision
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float(1.6)
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float(1.5)
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float(-1.6)
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float(-1.5)
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Using PHP_ROUND_HALF_DOWN with 1 decimal digit precision
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float(1.5)
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float(1.5)
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float(-1.5)
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float(-1.5)
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Using PHP_ROUND_HALF_EVEN with 1 decimal digit precision
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float(1.6)
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float(1.5)
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float(-1.6)
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float(-1.5)
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Using PHP_ROUND_HALF_ODD with 1 decimal digit precision
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float(1.5)
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float(1.5)
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float(-1.5)
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float(-1.5)
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]]>
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</screen>
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</example>
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</para>
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</refsect1>
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<refsect1 role="changelog">
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&reftitle.changelog;
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<para>
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>5.3.0</entry>
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<entry>
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The <parameter>mode</parameter> parameter was introduced.
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</entry>
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</row>
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<row>
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<entry>5.2.7</entry>
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<entry>
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The inner workings of <function>round</function> was changed
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to conform to the C99 standard.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>ceil</function></member>
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<member><function>floor</function></member>
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<member><function>number_format</function></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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-->
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