# include filename 和 # include"filename"之间的区别是什么？

Question

In the C and C++ programming languages, what is the difference between using angle brackets and using quotes in an include statement, as follows?

1. #include <filename>
2. #include "filename"

转载于:https://stackoverflow.com/questions/21593/what-is-the-difference-between-include-filename-and-include-filename

Answer 1

In practice, the difference is in the location where the preprocessor searches for the included file.

For #include <filename> the preprocessor searches in an implementation dependent manner, normally in search directories pre-designated by the compiler/IDE. This method is normally used to include standard library header files.

For #include "filename" the preprocessor searches first in the same directory as the file containing the directive, and then follows the search path used for the #include <filename> form. This method is normally used to include programmer-defined header files.

A more complete description is available in the GCC documentation on search paths.