我如何打印的__FILE__扩展到正确的字符串？ [英] How do I print the string which __FILE__ expands to correctly?

问题描述

考虑此程序：

#include <stdio.h>
int main() {
    printf("%s\n", __FILE__);
    return 0;
}

根据文件的名称，这个方案工作的 - 或没有。我现在面临的问题是，我想在一个编码安全的方式来打印当前文件的名称。然而，如果文件中有一些奇怪的字符，不能重新在当前code页面psented $ P $，编译器产生一个警告（理应如此）：

Depending on the name of the file, this program works - or not. The issue I'm facing is that I'd like to print the name of the current file in an encoding-safe way. However, in case the file has funny characters which cannot be represented in the current code page, the compiler yields a warning (rightfully so):

?????????.c(3) : warning C4566: character represented by universal-character-name '\u043F' cannot be represented in the current code page (1252)

我该如何解决呢？我想存储由 __ __ FILE 在例如给出的字符串UTF-16，这样我可以正常打印任何其他系统上运行时（通过将存储UTF-16重$ P $到任何运行时系统采用psentation）。要做到这一点，我需要知道：

How do I tackle this? I'd like to store the string given by __FILE__ in e.g. UTF-16 so that I can properly print it on any other system at runtime (by converting the stored UTF-16 representation to whatever the runtime system uses). To do so, I need to know:

1. 用于通过 __ __ FILE 指定字符串编码是什么？看来，至少在Windows上，目前系统code页面（在我的情况下，Windows 1252）使用 - 但这只是猜测。这是真的？


2. 如何存储字符串的UTF-8（或UTF-16）再presentation在编译的时候我的源$ C ​​$ C？

1. What encoding is used for the string given by __FILE__? It seems that, at least on Windows, the current system code page (in my case, Windows-1252) is used - but this is just guessing. Is this true?
2. How can I store the UTF-8 (or UTF-16) representation of that string in my source code at build time?

我的现实生活中的使用案例：我有一个跟踪当前执行的程序，写入电流源$ C ​​$ C /行号信息到一个文件中的宏。它看起来是这样的：

My real life use case: I have a macro which traces the current program execution, writing the current sourcecode/line number information to a file. It looks like this:

struct LogFile {
    // Write message to file. The file should contain the UTF-8 encoded data!
    void writeMessage( const std::string &msg );
};

// Global function which returns a pointer to the 'active' log file.
LogFile *activeLogFile();

#define TRACE_BEACON activeLogFile()->write( __FILE__ );

这打破情况下，当前的源文件具有包含不能重新当前code页面psented $ P $字符的名称。

This breaks in case the current source file has a name which contains characters which cannot be represented by the current code page.

推荐答案

使用可以使用标记粘贴运算符，如：

Use can use the token pasting operator, like this:

#define WIDEN2(x) L ## x
#define WIDEN(x) WIDEN2(x)
#define WFILE WIDEN(__FILE__)

int main() {
    wprintf("%s\n", WFILE);
    return 0;
}

这篇关于我如何打印的__FILE__扩展到正确的字符串？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！