philip Sat May 31 18:37:28 2003 EDT
Modified files:
/phpdoc/en/appendices comparisons.xml
Log:
Add undefined var and boolean true to the function comparison table, added
a note about if ($x) producing E_NOTICE for undefined variables. And
clarified the boolean column means if ($x). And, added some <type> references.
Index: phpdoc/en/appendices/comparisons.xml
diff -u phpdoc/en/appendices/comparisons.xml:1.3
phpdoc/en/appendices/comparisons.xml:1.4
--- phpdoc/en/appendices/comparisons.xml:1.3 Fri May 30 18:18:10 2003
+++ phpdoc/en/appendices/comparisons.xml Sat May 31 18:37:28 2003
@@ -1,5 +1,5 @@
<?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.3 $ -->
+<!-- $Revision: 1.4 $ -->
<appendix id="types.comparisons">
<title>PHP type comparison tables</title>
<para>
@@ -16,7 +16,8 @@
Before utilizing these tables, it's important to understand types and their
meanings. For example, <literal>"42"</literal> is a <type>string</type>
while <literal>42</literal> is an <type>integer</type>. &false; is a
- boolean while <literal>"false"</literal> is a string.
+ <type>boolean</type> while <literal>"false"</literal> is a
+ <type>string</type>.
</para>
<note>
<para>
@@ -25,6 +26,14 @@
<function>is_numeric</function>.
</para>
</note>
+ <note>
+ <para>
+ Simply doing <literal>if ($x)</literal> while <varname>$x</varname> is
+ undefined will generate an error of level <constant>E_NOTICE</constant>.
+ Instead, consider using <function>empty</function> or
+ <function>isset</function> and/or initialize your variables.
+ </para>
+ </note>
<para>
<table>
<title>Comparisons of <varname>$x</varname> with PHP functions</title>
@@ -36,7 +45,7 @@
<entry><function>empty</function></entry>
<entry><function>is_null</function></entry>
<entry><function>isset</function></entry>
- <entry><type>boolean</type></entry>
+ <entry><type>boolean</type> : <literal>if($x)</literal></entry>
</row>
</thead>
<tbody>
@@ -65,6 +74,14 @@
<entry>&false;</entry>
</row>
<row>
+ <entry><varname>$x</varname> is undefined</entry>
+ <entry><type>NULL</type></entry>
+ <entry>&true;</entry>
+ <entry>&true;</entry>
+ <entry>&false;</entry>
+ <entry>&false;</entry>
+ </row>
+ <row>
<entry><literal>$x = array();</literal></entry>
<entry><type>array</type></entry>
<entry>&true;</entry>
@@ -79,6 +96,14 @@
<entry>&false;</entry>
<entry>&true;</entry>
<entry>&false;</entry>
+ </row>
+ <row>
+ <entry><literal>$x = true;</literal></entry>
+ <entry><type>boolean</type></entry>
+ <entry>&false;</entry>
+ <entry>&false;</entry>
+ <entry>&true;</entry>
+ <entry>&true;</entry>
</row>
<row>
<entry><literal>$x = 1;</literal></entry>
--
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