<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >round</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="PHP 手册" HREF="index.html"><LINK REL="UP" TITLE="Math 数学函数" HREF="ref.math.html"><LINK REL="PREVIOUS" TITLE="rand" HREF="function.rand.html"><LINK REL="NEXT" TITLE="sin" HREF="function.sin.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >PHP 手册</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.rand.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.sin.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.round" ></A >round</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN109058" ></A ><P > (PHP 3, PHP 4, PHP 5)</P >round -- 对浮点数进行四舍五入</DIV ><DIV CLASS="refsect1" ><A NAME="AEN109061" ></A ><H2 >说明</H2 >float <B CLASS="methodname" >round</B > ( float val [, int precision] )<BR ></BR ><P > 返回将 <CODE CLASS="parameter" >val</CODE > 根据指定精度 <CODE CLASS="parameter" >precision</CODE >(十进制小数点后数字的数目)进行四舍五入的结果。<CODE CLASS="parameter" >precision</CODE > 也可以是负数或零(默认值)。 </P ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN109077" ></A ><P ><B >例 1. <B CLASS="function" >round()</B > 例子</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">3.4</font><font color="#007700">); </font><font color="#FF8000">// 3<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">3.5</font><font color="#007700">); </font><font color="#FF8000">// 4<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">3.6</font><font color="#007700">); </font><font color="#FF8000">// 4<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">3.6</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">); </font><font color="#FF8000">// 4<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">1.95583</font><font color="#007700">, </font><font color="#0000BB">2</font><font color="#007700">); </font><font color="#FF8000">// 1.96<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">1241757</font><font color="#007700">, -</font><font color="#0000BB">3</font><font color="#007700">); </font><font color="#FF8000">// 1242000<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">5.045</font><font color="#007700">, </font><font color="#0000BB">2</font><font color="#007700">); </font><font color="#FF8000">// 5.05<br /></font><font color="#007700">echo </font><font color="#0000BB">round</font><font color="#007700">(</font><font color="#0000BB">5.055</font><font color="#007700">, </font><font color="#0000BB">2</font><font color="#007700">); </font><font color="#FF8000">// 5.06<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE > </P ><P > <DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > PHP 默认不能正确处理类似 <TT CLASS="literal" >"12,300.2"</TT > 的字符串。见<A HREF="language.types.string.html#language.types.string.conversion" >字符串转换为数值</A >。 </P ></BLOCKQUOTE ></DIV > </P ><P > <DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >注意: </B > <CODE CLASS="parameter" >precision</CODE > 参数是在 PHP 4 中被引入的。 </P ></BLOCKQUOTE ></DIV > </P ><P > 参见 <A HREF="function.ceil.html" ><B CLASS="function" >ceil()</B ></A >,<A HREF="function.floor.html" ><B CLASS="function" >floor()</B ></A > 和 <A HREF="function.number-format.html" ><B CLASS="function" >number_format()</B ></A >。 </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.rand.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >起始页</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.sin.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >rand</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.math.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >sin</TD ></TR ></TABLE ></DIV ></BODY ></HTML >