philip Sat Sep 28 23:39:23 2002 EDT
Modified files:
/phpdoc/en/appendices about.xml
Log:
Moving section on "How to read a function definition" here from tutorial.xml
Index: phpdoc/en/appendices/about.xml
diff -u phpdoc/en/appendices/about.xml:1.16 phpdoc/en/appendices/about.xml:1.17
--- phpdoc/en/appendices/about.xml:1.16 Mon Aug 19 21:27:07 2002
+++ phpdoc/en/appendices/about.xml Sat Sep 28 23:39:23 2002
@@ -1,5 +1,5 @@
<?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.16 $ -->
+<!-- $Revision: 1.17 $ -->
<!--
TODO: add manual conventions section (eg. how to read
@@ -110,6 +110,133 @@
the quality or accuracy of the manual text itself.)
</para>
</note>
+ </sect1>
+
+ <sect1 id="about.prototypes">
+ <title>How to read a function definition (prototype)</title>
+ <para>
+ Each function is documented for quick reference, knowing how
+ to read and understand the manual will make using PHP
+ much easier. Rather than relying on examples or cut/paste, you want
+ to know how to read function definitions (prototypes). Let's begin:
+ </para>
+ <note>
+ <title>
+ Prerequisite: Basic understanding of <link linkend="language.types">types</link>
+ </title>
+ <para>
+ Although PHP is a loosly typed language, it's important to have
+ a basic understanding of <link linkend="language.types">types</link> as
+ they have important meaning.
+ </para>
+ </note>
+ <para>
+ Function definitions tell us what
+ type of value is <link linkend="functions.returning-values">returned</link>,
+ let's use the definition for <function>strlen</function> as our first example:
+ </para>
+ <para>
+ <screen role="html">
+strlen
+
+(PHP 3, PHP 4 >= 4.0.0)
+strlen -- Get string length
+
+Description
+int strlen ( string str )
+
+Returns the length of string.
+ </screen>
+ </para>
+ <para>
+ <table>
+ <title>Explanation of a function definition</title>
+ <tgroup cols="2">
+ <thead>
+ <row>
+ <entry>Part</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>
+ strlen
+ </entry>
+ <entry>
+ The function name.
+ </entry>
+ </row>
+ <row>
+ <entry>
+ (PHP 3, PHP 4 >= 4.0.0)
+ </entry>
+ <entry>
+ strlen() has been around in both all of PHP 3 and PHP 4
+ </entry>
+ </row>
+ <row>
+ <entry>
+ int
+ </entry>
+ <entry>
+ Type of value this function returns, which is an
+ <link linkend="language.types.integer">integer</link>
+ (i.e. The length of a string is measured in numbers).
+ </entry>
+ </row>
+ <row>
+ <entry>
+ ( string str )
+ </entry>
+ <entry>
+ The first (and in this case the only) parameter/argument for the
+ function strlen() is named <parameter>str</parameter>, and it's a
+ <link linkend="language.types.string">string</link>.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </para>
+ <para>
+ We could rewrite the above function definition in a generic way:
+ </para>
+ <para>
+ <screen role="html">
+ returned type function name ( parameter type parameter name )
+ </screen>
+ </para>
+ <para>
+ Many functions take on multiple parameters, such as
+<function>in_array</function>.
+ It's prototype is as follows:
+ </para>
+ <para>
+ <screen role="html">
+ bool in_array ( mixed needle, array haystack [, bool strict])
+ </screen>
+ </para>
+ <para>
+ What does this mean? in_array() returns a
+ <link linkend="language.types.boolean">boolean</link> value, &true; on
+ success (the <parameter>needle</parameter> was found in the
+ <parameter>haystack</parameter>) or &false; on failure (the
+ <parameter>needle</parameter> was not found in the
+ <parameter>haystack</parameter>). The first parameter is named
+ <parameter>needle</parameter> and it can be many different
+ <link linkend="language.types">types</link>, so we call it
+ "<emphasis>mixed</emphasis>". This mixed <parameter>needle</parameter>
+ (what we're looking for) can either be a scalar value (string, integer,
+ or <link linkend="language.types.float">float</link>), or an
+ <link linkend="language.types.array">array</link>.
+ <parameter>haystack</parameter> (the array we're searching in) is the
+ second parameter. The third <emphasis>optional</emphasis> parameter is
+ named <parameter>strict</parameter>. All optional parameters are seen
+ in <emphasis>[</emphasis> brackets <emphasis>]</emphasis>. The manual
+ states that the <parameter>strict</parameter> parameter defaults to
+ boolean &false;. See the manual page on each function for details on
+ how they work.
+ </para>
</sect1>
<sect1 id="about.more">
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