March 2017
Intermediate to advanced
364 pages
9h 45m
Japanese
Content preview from 初めてのPHP
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239
12
章
デバッグ
最初から正しく動作するプログラムはほとんどありません。本章では、プログラム内部の問題を
探し出して修正するテクニックを紹介します。PHP 初心者が書くプログラムは、おそらく PHP の
達人が書くプログラムより単純でしょう。しかし、一般的に初心者のプログラムで発生するエラー
はそれほど単純ではなく、エラーを探し出して修正するには達人と同じツールとテクニックを使う
必要があります。
12.1
エラー出力場所の制御
PHP エンジンにエラーメッセージを生成させるプログラムには、問題がたくさんある可能性が
あります。エラーメッセージの出力場所は指定できます。エラーメッセージを他のプログラムの出
力と一緒に Web ブラウザに送ることができます。また、Web サーバのエラーログに含めることも
できます。
エラーメッセージの表示先を設定する際には、PHP プログラムの開発中にはエラーを画面に表
示し、開発が完了して実際
にプログラムを使っているときにはエラーログに送ると便利です。プロ
グラムの開発中は、例えば特定の行のパースエラーがすぐにわかると助かります。しかし、プログ
ラムが（一応は）動作して同僚やユーザが使っていたりすると、このようなエラーメッセージは混
乱を招いてしまうでしょう。
エラーメッセージをブラウザに表示するには、
display_errors
構成ディレクティブを
On
に設定
します。エラーメッセージをブラウザに表示させないようにするには、
display_errors
構成ディ
レクティ
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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.