9.5.7 Line directives

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最新推荐文章于 2024-07-10 20:42:48 发布

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分类专栏： c#/c++ 文章标签： compiler whitespace character numbers warnings processing

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本文介绍了C#编译器中的行指令，它可改变编译器输出警告和错误时报告的行号与源文件名，常用于从其他文本输入生成C#源代码的元编程工具。还说明了行指令的语法格式，以及无指令、非默认和默认行指令时编译器的处理方式。

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9.5.7 Line directives
Line directives may be used to alter the line numbers and source file names
that are reported by the compiler in
output such as warnings and errors.
[Note: Line directives are most commonly used in meta-programming tools
that generate C# source code from
some other text input. end note]
pp-line::
whitespaceopt # whitespaceopt line whitespace line-indicator pp-new-line
line-indicator::
decimal-digits whitespace file-name
decimal-digits
default
file-name::
" file-name-characters "
file-name-characters::
file-name-character
file-name-characters file-name-character
file-name-character::
Any character except " (U+0022), and new-line
When no #line directives are present, the compiler reports true line
numbers and source file names in its output.
When processing a #line directive that includes a line-indicator that is
not default, the compiler treats the line
after the directive as having the given line number (and file name, if
specified).
A #line default directive reverses the effect of all preceding #line
directives. The compiler reports true line
information for subsequent lines, precisely as if no #line directives had
been processed.
[Note: Note that a file-name differs from a regular string literal in that
escape characters are not processed; the
./. character simply designates an ordinary back-slash character within a
file-name. end note]