C Reference Manual Reading Notes: 002 Whitespace, Line Termination, and Lines Length Limits

最新推荐文章于 2025-08-30 09:30:00 发布

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#whitespace #reference #c #character #preprocessor #comments

本文介绍了C语言中空白字符（WSC）的概念及其使用方式，包括空格、制表符等，这些字符通常用于分隔标识符。此外还探讨了换行字符的作用及如何通过反斜杠进行行连接。

The blank(space), end-of-line, VT, FF, HT, and comments are known collectively as whitespace character (WSC). These characters are ignored except insofar as they are used to separate adjacent tokens or when they appera in character constans, string constans, or #include file names. WCS may be used to lay out the C program in a way that is pleasing to a human reader.

The end-of-line character or character sequence marks the end of source program lines. In some emplementations, the formatting characters CR, FF, VT additionally terminate source lines, and are called line break characters. Line Termination is important for the recognition of preprocessor control lines.

A source line can be continued onto the next line by ending the first line with a backslash(/) or with the trigraph ??/. Most C implementation impose a limit on the maximum length of source lines both before and after splicing continuation lines. C89 require to permit logical source lines of at least 509 characters; C99 allows 4095 characters.