c++ - 在 C++ 中包含头文件时尖括号 < > 和双引号 ""之间的区别？

Question

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What is the difference between #include <filename> and #include “filename”?

尖括号< >有什么区别和双引号 " "同时在 C++ 中包含头文件？

我的意思是应该包含哪些文件，例如:#include <QPushButton>以及要包含哪些文件，例如:#include "MyFile.h" ？？？

Answer 1

它依赖于编译器。也就是说，一般使用 "将当前工作目录中的 header 优先于系统 header 。 <>通常用于系统头文件。从到规范(第 6.10.2 节):

A preprocessing directive of the form

  # include <h-char-sequence> new-line

searches a sequence of implementation-defined places for a header identified uniquely by the specified sequence between the < and > delimiters, and causes the replacement of that directive by the entire contents of the header. How the places are specified or the header identified is implementation-defined.

A preprocessing directive of the form

  # include "q-char-sequence" new-line

causes the replacement of that directive by the entire contents of the source file identified by the specified sequence between the " delimiters. The named source file is searched for in an implementation-defined manner. If this search is not supported, or if the search fails, the directive is reprocessed as if it read

  # include <h-char-sequence> new-line

with the identical contained sequence (including > characters, if any) from the original directive.

所以在大多数编译器上，使用""首先检查您的本地目录，如果找不到匹配项，则继续检查系统路径。使用 <>以系统标题开始搜索。