获取当前目录的跨平台方式是什么？

I need a cross-platform way to get the current working directory (yes, getcwd does what I want). I thought this might do the trick:

我需要一种跨平台的方式来获取当前的工作目录(是的,getcwd做我想要的)。我认为这可能会成功:

#ifdef _WIN32
    #include <direct.h>
    #define getcwd _getcwd // stupid MSFT "deprecation" warning
#elif
    #include <unistd.h>
#endif
#include <string>
#include <iostream>
using namespace std;

int main()
{
    string s_cwd(getcwd(NULL,0));
    cout << "CWD is: " << s_cwd << endl;
}

I got this reading:

我读到了这个:

_getcwd at MSDN

在MSDN上_getcwd

getcwd at Kernel.org

getcwd在Kernel.org

getcwd at Apple.com

来自Apple.com的getcwd

There should be no memory leaks, and it should work on a Mac as well, correct?

应该没有内存泄漏,它也可以在Mac上运行,对吗?

UPDATE: I fear something is still wrong here (I'm trying to avoid creating a char array with a determined length, as there's no proper way to get a decent length for getcwd):

更新:我担心这里仍然存在错误(我试图避免创建一个具有确定长度的char数组,因为没有正确的方法来获得getcwd的合适长度):

char* a_cwd = getcwd(NULL,0);
string s_cwd(a_cwd);
free(a_cwd); // or delete a_cwd?

3 个解决方案

#1

You cannot call getcwd with a NULL buffer. As per the Opengroup:

您不能使用NULL缓冲区调用getcwd。根据Opengroup:

If buf is a null pointer, the behavior of getcwd() is unspecified.

如果buf是空指针,则未指定getcwd()的行为。

Also, getcwd can return NULL which can break a string constructor.

此外,getcwd可以返回NULL,这可能会破坏字符串构造函数。

You'll need to change that to something like:

您需要将其更改为:

char buffer[SIZE];
char *answer = getcwd(buffer, sizeof(buffer));
string s_cwd;
if (answer)
{
    s_cwd = answer;
}

#2

If it is no problem for you to include, use boost filesystem for convenient cross-platform filesystem operations.

如果您没有问题,请使用boost文件系统来实现方便的跨平台文件系统操作。

boost::filesystem::path full_path( boost::filesystem::current_path() );

Here is an example.

这是一个例子。

EDIT: as pointed out by Roi Danton in the comments, filesystem became part of the ISO C++ in C++17, so boost is not needed anymore:

编辑:正如Roi Danton在评论中所指出的,文件系统成为了C ++ 17中ISO C ++的一部分,因此不再需要boost:

std::filesystem::current_path();

#3

Calling getcwd with a NULL pointer is implementation defined. It often does the allocation for you with malloc (in which case your code does have a memory leak). However, it isn't guaranteed to work at all. So you should allocate your own buffer.

使用NULL指针调用getcwd是实现定义的。它通常使用malloc为您分配(在这种情况下,您的代码确实存在内存泄漏)。但是,它并不能保证完全有效。所以你应该分配自己的缓冲区。

char *cwd_buffer = malloc(sizeof(char) * max_path_len);
char *cwd_result = getcwd(cwd_buffer, max_path_len);

The Open Group has an example showing how to get the max path length from _PC_PATH_MAX. You could consider using MAX_PATH on Windows. See this question for caveats to this number on both platforms.

Open Group有一个示例显示如何从_PC_PATH_MAX获取最大路径长度。您可以考虑在Windows上使用MAX_PATH。在两个平台上都可以看到这个问题。

#1