Is the code written in Japanese? Are filenames in English? What about like a C preprocessor? Is that still in English? Are comments in Japanese?
Examples would be nice too.
closed as not constructive by Mason Wheeler, ChaosPandion, ChrisF♦ Feb 10 '11 at 22:17
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As someone who has programmed in Japan. I can honestly say that I have seen code in all forms. Most of the cleaner code that I have seen that was intended to be supported only by Japanese programmers had all of the comments and documentation in Japanese.
As for some of the horrendous code that I have seen, I remember seeing Java and (I believe) VB code that actually used kanji or katakana for variable names.
That aside, code tends to look like this
As for a C preprocessor, I have no idea.
In practice, most programming languages in active use outside of the US use keywords that resemble English, but it's important to realize that for the most part those of us who write code as native English speakers aren't really writing in "English", either.
There are a few dozen languages that actually support non-ASCII-range keywords and these are often designed to reduce the cognitive friction for non-English speakers trying to learn programming.
Additionally, some older implementations of languages that translate code into tokens (not true compiling), can spit out the same code in an editor using the, say, German equivalent; my first experience with Microsoft Office's VBA was like this when I was a student in Germany.
Many English-like programming languages, including C#, Java, and others, now allow variable names and method names in Japanese, as long as the source code is encoded in UTF-8 or another suitable encoding. It wasn't common to have even comments in Japanese in C, however, unless you were using a compiler that supported Shift-JIS or Unicode. String literals in C were almost always escaped using the literal encoding method unless you had an external resource file format to work with, as in Visual Studio.
In practice, many programs written by Japanese teams that don't expect to require maintenance outside of Japan are written with comments or javadoc/docstrings/etc. in Japanese. My wife generally writes code with a sort of Japanese-like English, using terms that didn't necessarily match my own use or understanding of English ("regist" for "post" or "story", regist_date for publication date), and occasional comments in Japanese or Janglish.
Most programs that have an international community around them, that originate in Japan, use some form of English naming convention. See, for example, Matz' source code for ruby.