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120 lines
4.8 KiB
HTML
120 lines
4.8 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2018 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using fast enumeration (Using the GNU Compiler Collection (GCC))</title>
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<meta name="description" content="Using fast enumeration (Using the GNU Compiler Collection (GCC))">
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<meta name="keywords" content="Using fast enumeration (Using the GNU Compiler Collection (GCC))">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Fast-enumeration.html#Fast-enumeration" rel="up" title="Fast enumeration">
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<link href="c99_002dlike-fast-enumeration-syntax.html#c99_002dlike-fast-enumeration-syntax" rel="next" title="c99-like fast enumeration syntax">
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<link href="Fast-enumeration.html#Fast-enumeration" rel="prev" title="Fast enumeration">
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<style type="text/css">
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Using-fast-enumeration"></a>
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<div class="header">
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<p>
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Next: <a href="c99_002dlike-fast-enumeration-syntax.html#c99_002dlike-fast-enumeration-syntax" accesskey="n" rel="next">c99-like fast enumeration syntax</a>, Up: <a href="Fast-enumeration.html#Fast-enumeration" accesskey="u" rel="up">Fast enumeration</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Using-Fast-Enumeration"></a>
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<h4 class="subsection">8.9.1 Using Fast Enumeration</h4>
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<p>GNU Objective-C provides support for the fast enumeration syntax:
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</p>
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<div class="smallexample">
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<pre class="smallexample"> id array = …;
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id object;
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for (object in array)
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{
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/* Do something with 'object' */
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}
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</pre></div>
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<p><code>array</code> needs to be an Objective-C object (usually a collection
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object, for example an array, a dictionary or a set) which implements
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the “Fast Enumeration Protocol” (see below). If you are using a
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Foundation library such as GNUstep Base or Apple Cocoa Foundation, all
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collection objects in the library implement this protocol and can be
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used in this way.
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</p>
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<p>The code above would iterate over all objects in <code>array</code>. For
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each of them, it assigns it to <code>object</code>, then executes the
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<code>Do something with 'object'</code> statements.
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</p>
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<p>Here is a fully worked-out example using a Foundation library (which
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provides the implementation of <code>NSArray</code>, <code>NSString</code> and
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<code>NSLog</code>):
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</p>
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<div class="smallexample">
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<pre class="smallexample"> NSArray *array = [NSArray arrayWithObjects: @"1", @"2", @"3", nil];
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NSString *object;
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for (object in array)
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NSLog (@"Iterating over %@", object);
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</pre></div>
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</body>
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</html>
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