blog/content/post/2008/07/11/2008-07-11-00000964.md

---
title: ポインタを使った演習も実践的になってきたよ
author: kazu634
date: 2008-07-11
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  - 'O:8:"stdClass":13:{s:6:"manual";b:0;s:11:"tweet_times";i:1;s:5:"delay";i:0;s:7:"enabled";i:1;s:10:"separation";s:2:"60";s:7:"version";s:3:"3.7";s:14:"tweet_template";b:0;s:6:"status";i:2;s:6:"result";a:0:{}s:13:"tweet_counter";i:2;s:13:"tweet_log_ids";a:1:{i:0;i:4129;}s:9:"hash_tags";a:0:{}s:8:"accounts";a:1:{i:0;s:7:"kazu634";}}'
categories:
  - C
  - Programming

---
<div class="section">
<p>
    『<a href="http://d.hatena.ne.jp/asin/4774111422" onclick="__gaTracker('send', 'event', 'outbound-article', 'http://d.hatena.ne.jp/asin/4774111422', 'C言語ポインタ完全制覇 (標準プログラマーズライブラリ)');">C言語ポインタ完全制覇 (標準プログラマーズライブラリ)</a>』の勉強だよ。
</p>

<h4>
    mallocを用いた可変長配列
</h4>

<pre class="syntax-highlight">
<span class="synComment">/* ======================= */</span>
<span class="synComment">/* === Include library === */</span>
<span class="synComment">/* ======================= */</span>
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdlib.h&#62;</span>
<span class="synComment">/* ================= */</span>
<span class="synComment">/* === Functions === */</span>
<span class="synComment">/* ================= */</span>
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">char</span>	 buf[<span class="synConstant">256</span>];
<span class="synType">int</span>	 size;
<span class="synType">int</span>	*variable_array;
<span class="synType">int</span>	 i;
printf(<span class="synConstant">&#34;Input Array Size: &#34;</span>);
<span class="synComment">/* Read Data from STDIN */</span>
fgets(buf, <span class="synConstant">256</span>, <span class="synConstant">stdin</span>);
sscanf(buf, <span class="synConstant">&#34;</span><span class="synSpecial">%d</span><span class="synConstant">&#34;</span>, &#38;size);
variable_array = malloc(<span class="synStatement">sizeof</span>(<span class="synType">int</span>) * size);
<span class="synStatement">for</span> (i = <span class="synConstant"></span>; i &#60; size; ++i)
{
variable_array[i] = i;
}
<span class="synStatement">for</span> (i = <span class="synConstant"></span>;i &#60; size; ++i)
{
printf(<span class="synConstant">&#34;variable_array[</span><span class="synSpecial">%d</span><span class="synConstant">] : </span><span class="synSpecial">%d\n</span><span class="synConstant">&#34;</span>, i, variable_array[i]);
}
<span class="synStatement">return</span> <span class="synConstant"></span>;
}
</pre>

<h4>
    可変長配列の配列の一つの例
</h4>

<pre class="syntax-highlight">
<span class="synComment">/* ======================= */</span>
<span class="synComment">/* === Include library === */</span>
<span class="synComment">/* ======================= */</span>
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdio.h&#62;</span>
<span class="synPreProc">#include </span><span class="synConstant">&#60;stdlib.h&#62;</span>
<span class="synPreProc">#include </span><span class="synConstant">&#60;string.h&#62;</span>
<span class="synComment">/* ================= */</span>
<span class="synComment">/* === Functions === */</span>
<span class="synComment">/* ================= */</span>
<span class="synType">void</span> read_slogan(<span class="synType">FILE</span> *fp, <span class="synType">char</span> **slogan)
{
<span class="synType">char</span>	buf[<span class="synConstant">1024</span>];
<span class="synType">int</span>	i;
<span class="synStatement">for</span> (i = <span class="synConstant"></span>; i &#60; <span class="synConstant">7</span>; i++)
{
fgets(buf, <span class="synConstant">1024</span>, fp);
buf[strlen(buf) - <span class="synConstant">1</span>] = <span class="synSpecial">'\0'</span>;
slogan[i] = malloc(<span class="synStatement">sizeof</span>(<span class="synType">char</span>) * (strlen(buf) + <span class="synConstant">1</span>));
strcpy(slogan[i], buf);
}
}
<span class="synType">int</span> main(<span class="synType">void</span>)
{
<span class="synType">char</span>	*slogan[<span class="synConstant">7</span>];
<span class="synType">int</span>	 i;
read_slogan(<span class="synConstant">stdin</span>, slogan);
<span class="synStatement">for</span> (i = <span class="synConstant"></span>; i &#60; <span class="synConstant">7</span>; ++i)
{
printf(<span class="synConstant">&#34;</span><span class="synSpecial">%s\n</span><span class="synConstant">&#34;</span>, slogan[i]);
}
<span class="synStatement">return</span> <span class="synConstant"></span>;
}
</pre>

<div class="hatena-asin-detail">
<a href="http://www.amazon.co.jp/dp/4774111422/?tag=hatena_st1-22&ascsubtag=d-7ibv" onclick="__gaTracker('send', 'event', 'outbound-article', 'http://www.amazon.co.jp/dp/4774111422/?tag=hatena_st1-22&ascsubtag=d-7ibv', '');"><img src="https://images-na.ssl-images-amazon.com/images/I/51FT9JJP2VL._SL160_.jpg" class="hatena-asin-detail-image" alt="C言語ポインタ完全制覇 (標準プログラマーズライブラリ)" title="C言語ポインタ完全制覇 (標準プログラマーズライブラリ)" /></a></p>

<div class="hatena-asin-detail-info">
<p class="hatena-asin-detail-title">
<a href="http://www.amazon.co.jp/dp/4774111422/?tag=hatena_st1-22&ascsubtag=d-7ibv" onclick="__gaTracker('send', 'event', 'outbound-article', 'http://www.amazon.co.jp/dp/4774111422/?tag=hatena_st1-22&ascsubtag=d-7ibv', 'C言語ポインタ完全制覇 (標準プログラマーズライブラリ)');">C言語ポインタ完全制覇 (標準プログラマーズライブラリ)</a>
</p>

<ul>
<li>
<span class="hatena-asin-detail-label">作者:</span> <a href="http://d.hatena.ne.jp/keyword/%C1%B0%B6%B6%CF%C2%CC%EF" onclick="__gaTracker('send', 'event', 'outbound-article', 'http://d.hatena.ne.jp/keyword/%C1%B0%B6%B6%CF%C2%CC%EF', '前橋和弥');" class="keyword">前橋和弥</a>
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</li>
<li>
<span class="hatena-asin-detail-label">発売日:</span> 2001/01
</li>
<li>
<span class="hatena-asin-detail-label">メディア:</span> 単行本
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<li>
<span class="hatena-asin-detail-label">購入</span>: 22人 <span class="hatena-asin-detail-label">クリック</span>: 147回
</li>
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