68 lines
3.7 KiB
Markdown
68 lines
3.7 KiB
Markdown
---
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title: '『[新版Perl言語プログラミングレッスン入門編』第10章 サブルーチン'
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author: kazu634
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date: 2008-03-09
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wordtwit_post_info:
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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:3805;}s:9:"hash_tags";a:0:{}s:8:"accounts";a:1:{i:0;s:7:"kazu634";}}'
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categories:
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- Perl
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- Programming
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---
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<div class="section">
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<p>
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今日はサブルーチンだよー。
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</p>
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<p>
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<a name="seemore"></a>
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</p>
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<h4>
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簡単なサブルーチン
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</h4>
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<pre class="syntax-highlight">
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<span class="synStatement">use strict</span>;
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<span class="synStatement">use warnings</span>;
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<span class="synStatement">my</span> (<span class="synIdentifier">$x</span>, <span class="synIdentifier">$y</span>) = (<span class="synConstant">123</span>, <span class="synConstant">456</span>);
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<span class="synIdentifier">&print_xy</span>(<span class="synIdentifier">$x</span>, <span class="synIdentifier">$y</span>);
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<span class="synStatement">sub</span><span class="synIdentifier"> print_xy </span>{
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<span class="synStatement">my</span> (<span class="synIdentifier">$x</span>, <span class="synIdentifier">$y</span>) = <span class="synIdentifier">@_</span>;
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<span class="synStatement">print</span> <span class="synConstant">"</span><span class="synSpecial">\$</span><span class="synConstant">x = </span><span class="synIdentifier">$x</span><span class="synSpecial">\n</span><span class="synConstant">"</span>;
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<span class="synStatement">print</span> <span class="synConstant">"</span><span class="synSpecial">\$</span><span class="synConstant">y = </span><span class="synIdentifier">$y</span><span class="synSpecial">\n</span><span class="synConstant">"</span>;
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}
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</pre>
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<p>
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「&…」でサブルーチン呼び出しという意味になる。「@_」は引数のリストという意味かな？
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</p>
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<h4>
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戻り値のあるサブルーチン
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</h4>
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<p>
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戻り値のあるサブルーチンは、returnを用いると実現できるよ！
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</p>
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<pre class="syntax-highlight">
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<span class="synStatement">use strict</span>;
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<span class="synStatement">use warnings</span>;
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<span class="synStatement">print</span> <span class="synIdentifier">&calc_ave</span>(<span class="synConstant">100</span>, <span class="synConstant">50</span>, <span class="synConstant">30</span>, <span class="synConstant">20</span>) , <span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>;
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<span class="synStatement">sub</span><span class="synIdentifier"> calc_ave </span>{
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<span class="synStatement">my</span> <span class="synIdentifier">@nums</span> = <span class="synIdentifier">@_</span>;
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<span class="synStatement">my</span> <span class="synIdentifier">$sum</span>;
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<span class="synStatement">foreach</span> (<span class="synIdentifier">@nums</span>) {
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<span class="synIdentifier">$sum</span> = <span class="synIdentifier">$sum</span> + <span class="synIdentifier">$_</span>;
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}
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<span class="synStatement">my</span> <span class="synIdentifier">$ave</span> = <span class="synIdentifier">$sum</span> / <span class="synIdentifier">@nums</span>;
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<span class="synStatement">return</span> <span class="synIdentifier">$ave</span>
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}
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</pre>
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<p>
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本に載っているやつだと汎用的じゃあなかったから、引数が何個でも大丈夫なようにしてみた。直前の章のコンテクストがうまく理解できている気がする（ my $ave = $sum / @nums。この場合スカラーコンテクストだから、@numsは配列の要素数になるんだよね）。
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</p>
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</div>
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