<HTML ><HEAD ><TITLE >empty("0")</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="PHP Manual" HREF="index.html"><LINK REL="UP" TITLE="Migrating from PHP 3 to PHP 4" HREF="migration4.html"><LINK REL="PREVIOUS" TITLE="Initializers" HREF="migration4.initializers.html"><LINK REL="NEXT" TITLE="Missing functions" HREF="migration4.missing.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=ISO-8859-1"></HEAD ><BODY CLASS="section" 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 Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="migration4.initializers.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Appendix B. Migrating from PHP 3 to PHP 4</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="migration4.missing.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="migration4.empty" ></A ><TT CLASS="literal" >empty("0")</TT ></H1 ><P > The perhaps most controversial change in behavior has happened to the behavior of the <A HREF="function.empty.html" ><B CLASS="function" >empty()</B ></A >. A String containing only the character '0' (zero) is now considered empty while it wasn't in PHP 3. </P ><P > This new behavior makes sense in web applications, with all input fields returning strings even if numeric input is requested, and with PHP's capabilities of automatic type conversion. But on the other hand it might break your code in a rather subtle way, leading to misbehavior that is hard to track down if you do not know about what to look for. </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="migration4.initializers.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="migration4.missing.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Initializers</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="migration4.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Missing functions</TD ></TR ></TABLE ></DIV ></BODY ></HTML >