March 2017
Intermediate to advanced
364 pages
9h 45m
Japanese
Content preview from 初めてのPHP
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5.4
変数スコープ
87
例5-19 では、
complete_bill()
関数は税金とチップを含む請求額が
$cash_on_hand
より多ければ
false
を返します。請求額が
$cash_on_hand
以下であれば、請求額を返します。関数外の
if()
文が
テスト式を評価するときには、以下が行われます。
1. 引数
15.22
、
8.25
、
15
、
20
で
complete_bill()
を呼び出す。
2.
complete_bill()
の返り値を
$total
に代入する。
3. 代入結果（代入された値と同じになる）を
true
か
false
のどちらかに変換し、テスト式の最終
結果として使う。
5.4
変数スコープ
例5-9 で説明したように、関数内で引数の変数を変更しても、関数外の変数には影響を与えませ
ん。なぜなら、関数内の動作は異なるスコープで起こるからです。関数外で定義した変数はグロー
バル変数と呼ばれ、1 つのスコープの中にあります。関数内で定義した
変数はローカル変数と呼ば
れます。関数ごとに別々のスコープを持っています。
各関数が大企業の支社、関数外のコードは本社であると考えてください。フィラデルフィア支社
のオフィスでは、社員は「アリスはこの素晴らしい報告書を書いたよ」とか「ボブが僕のコーヒーに
いれる砂糖の量はいつもいいかげんだ」など、互いを名前で呼び合います。このような発言はフィラ
デルフィア支社（ある関数のローカル変数）の社員についての話題で、別の支社（他の関数のローカ
ル変数）や本社（グローバル変数）
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.