C语言中可用的标准预定义宏__FILE__显示文件的完整路径。有办法缩短这条路吗?我的意思是

/full/path/to/file.c

我看到

to/file.c

or

file.c

当前回答

我多年来一直使用@Patrick的答案。

当完整路径包含符号链接时,它有一个小问题。

更好的解决方案。

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-builtin-macro-redefined -D'__FILE__=\"$(subst $(realpath ${CMAKE_SOURCE_DIR})/,,$(abspath $<))\"'")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-builtin-macro-redefined -D'__FILE__=\"$(subst $(realpath ${CMAKE_SOURCE_DIR})/,,$(abspath $<))\"'")

为什么要用这个?

-Wno-builtin-macro-redefined to mute the compiler warnings for redefining __FILE__ macro. For those compilers do not support this, refer to the Robust way below. Strip the project path from the file path is your real requirement. You won't like to waste the time to find out where is a header.h file, src/foo/header.h or src/bar/header.h. We should strip the __FILE__ macro in cmake config file. This macro is used in most exists codes. Simply redefine it can set you free. Compilers like gcc predefines this macro from the command line arguments. And the full path is written in makefiles generated by cmake. Hard code in CMAKE_*_FLAGS is required. There is some commands to add compiler options or definitions in some more recently version, like add_definitions() and add_compile_definitions(). These commands will parse the make functions like subst before apply to source files. That is not we want.

重新定义- wno -内置宏的健壮方法。

include(CheckCCompilerFlag)
check_c_compiler_flag(-Wno-builtin-macro-redefined SUPPORT_C_WNO_BUILTIN_MACRO_REDEFINED)
if (SUPPORT_C_WNO_BUILTIN_MACRO_REDEFINED)
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-builtin-macro-redefined")
endif (SUPPORT_C_WNO_BUILTIN_MACRO_REDEFINED)
include(CheckCXXCompilerFlag)
check_cxx_compiler_flag(-Wno-builtin-macro-redefined SUPPORT_CXX_WNO_BUILTIN_MACRO_REDEFINED)
if (SUPPORT_CXX_WNO_BUILTIN_MACRO_REDEFINED)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-builtin-macro-redefined")
endif (SUPPORT_CXX_WNO_BUILTIN_MACRO_REDEFINED)

记住从集合(*_FLAGS…-D__FILE__ =…)。

其他回答

red1ynx的答案经过调整,甚至更加“臃肿”:

#define __FILENAME__ \
  (strchr(__FILE__, '\\') \
  ? ((strrchr(__FILE__, '\\') ? strrchr(__FILE__, '\\') + 1 : __FILE__)) \
  : ((strrchr(__FILE__, '/') ? strrchr(__FILE__, '/') + 1 : __FILE__)))

如果我们发现反斜杠,我们就分反斜杠。否则,拆分为正斜杠。很简单。

几乎任何替代方案都会更简洁(在我看来,c++ constexpr确实是这里的黄金标准)。然而,如果你正在使用一些__BASE_FILE__不可用的编译器,这可能是有帮助的。

如果您正在使用cmake,这里有一个提示。来自: http://public.kitware.com/pipermail/cmake/2013-January/053117.html

我在复制提示,所以都在这一页上:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D__FILENAME__='\"$(subst
  ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")

如果您正在使用GNU make,我认为没有理由不能将其扩展到您自己的make文件。例如,你可能有这样的一行:

CXX_FLAGS+=-D__FILENAME__='\"$(subst $(SOURCE_PREFIX)/,,$(abspath $<))\"'"

其中$(SOURCE_PREFIX)是要删除的前缀。

然后使用__FILENAME__代替__FILE__。

使用basename()函数,或者,如果是在Windows上,使用_splitpath()。

#include <libgen.h>

#define PRINTFILE() { char buf[] = __FILE__; printf("Filename:  %s\n", basename(buf)); }

还可以在shell中尝试man 3 basename。

c++ 11 msvc2015u3、gcc5.4 clang3.8.0 模板<typename T, size_t S> (const T (& str)[S], size_t i = S - 1) { 返回(str[i] == '/' || str[i] == '\\') ?I + 1:(I > 0 ?Get_file_name_offset (str, I - 1): 0); } template <typename T> (T (& str)[1]) { 返回0; }

'

    int main()
    {
         printf("%s\n", &__FILE__[get_file_name_offset(__FILE__)]);
    }

代码在以下情况下产生编译时偏移量:

gcc:至少gcc6.1 + -O1 Msvc:将结果放入constexpr变量: constexpr auto file = &__FILE__[get_file_name_offset(__FILE__)]; printf (" % s \ n ",文件); Clang:坚持不编译时计算

有一个技巧可以强制所有3个编译器进行编译时间计算,即使在调试配置中禁用优化:

    namespace utility {

        template <typename T, T v>
        struct const_expr_value
        {
            static constexpr const T value = v;
        };

    }

    #define UTILITY_CONST_EXPR_VALUE(exp) ::utility::const_expr_value<decltype(exp), exp>::value

    int main()
    {
         printf("%s\n", &__FILE__[UTILITY_CONST_EXPR_VALUE(get_file_name_offset(__FILE__))]);
    }

https://godbolt.org/z/u6s8j3

下面是一个解决方案,适用于没有字符串库的环境(Linux内核,嵌入式系统等):

#define FILENAME ({ \
    const char* filename_start = __FILE__; \
    const char* filename = filename_start; \
    while(*filename != '\0') \
        filename++; \
    while((filename != filename_start) && (*(filename - 1) != '/')) \
        filename--; \
    filename; })

现在只需使用FILENAME而不是__FILENAME__。是的,它仍然是一个运行时的东西,但它是有效的。