問78
頻出度★★☆
世界の主要な言語で使われている文字を一つの文字コード体系で取り扱うための規格はどれか。
平成25年度 春期 ITパスポート試験 問78
テクノロジ系基礎理論 › 情報に関する理論
This question's explanation and your answers so far.
解説
問 78
Incorrectア
Incorrect. ASCII is the most basic character code, defined in the United States. It represents one character in 7 bits, so it can express only 128 characters in total: uppercase letters, lowercase letters, digits, symbols, and control characters. It contains neither Japanese hiragana and kanji nor even the accented letters of German and French, so it cannot handle the characters used in the world's major languages. It is a historically important standard that became the foundation of Unicode, but it is not a standard that handles many languages in one system, so it is not appropriate.
Incorrectイ
Incorrect. EUC (Extended UNIX Code) is a character code that extends ASCII so that UNIX-family operating systems can handle characters other than letters and digits, and it is defined as a separate system for each language: EUC-JP for Japanese, EUC-KR for Korean, and EUC-CN for Chinese. In other words, although it does support several languages, it does so as multiple systems prepared language by language, not by handling the world's major languages together within the single character-encoding system the question asks for. It is therefore not appropriate.
Incorrectウ
Incorrect. SJIS (Shift JIS) is a Japanese-only encoding form that represents the half-width characters of JIS X 0201 and the kanji, hiragana, and katakana of JIS X 0208 in one or two bytes, and it was long used as the standard on personal computers and word processors in Japan. Its coverage is limited to Japanese (plus letters and digits equivalent to ASCII), and it does not include characters of other languages such as Hangul or Arabic script. Because it is a standard for one specific language, it does not satisfy the condition of handling the world's major languages in a single system, so it is not appropriate.
- エ
正解 The correct answer is エ, Unicode. Unicode is a character-code standard created so that the characters used in the world's major languages are collected into a single character-encoding system (one continuous code space) and given common numbers (code points). Besides letters, digits, and symbols, it can handle Japanese kanji, hiragana, and katakana, Chinese simplified and traditional characters, Hangul, Arabic script, Cyrillic, and Greek within the same system, so there is no need to switch to a different character code for each language, and characters of several languages can be mixed inside one document or one database. This is the decisive difference from earlier character codes, which were split into a separate standard for each language, and it matches exactly the condition in the question: handling the characters used in the world's major languages within a single character-encoding system. When text is actually represented on a computer, encoding forms such as UTF-8 and UTF-16 convert Unicode code points into byte sequences; UTF-8 in particular is compatible with ASCII (the ASCII range stays one byte with the same values), so it has spread widely as the standard character encoding on the Internet, for web pages, e-mail, and the like. Therefore エ is the appropriate standard for handling many languages in a single system.
ここがポイント
- Unicode is a character-code standard that unifies the characters of the world's major languages into one code system and assigns them common numbers; its defining feature is that several languages can be mixed inside one document. The forms that convert it into actual byte sequences are UTF-8 and UTF-16, and ASCII-compatible UTF-8 is widely used as the standard on the Web. Learn this relationship between the character set (Unicode) and the encoding forms (UTF-8 and others) together with the term itself.
- The other choices are character codes with limited coverage. ASCII is a 7-bit standard with only letters, digits, and symbols; Shift JIS is a Japanese-only encoding form; and EUC is split by language into EUC-JP, EUC-KR, and so on. None of them handles many languages in a single system. Character-code questions can be solved reliably by sorting them out with two checks: which language is covered, and whether the system is one or many.
用語