C ++如何检查文件的最后修改时间 [英] C++ How to check the last modified time of a file
问题描述
我正在缓存文件中的某些信息,并且希望能够定期检查文件的内容是否已被修改,以便在需要时可以再次读取文件以获取新内容.
I'm caching some information from a file and I want to be able to check periodically if the file's content has been modified so that I can read the file again to get the new content if needed.
这就是为什么我想知道是否存在一种方法来获取C ++中文件的上次修改时间.
That's why I'm wondering if there is a way to get a file's last modified time in C++.
推荐答案
没有特定于语言的方法来执行此操作,但是OS提供了必需的功能.在UNIX系统中,您需要stat
函数.在Visual Studio下为Windows提供了等效的_stat
函数.
There is no language-specific way to do this, however the OS provides the required functionality. In a unix system, the stat
function is what you need. There is an equivalent _stat
function provided for windows under Visual Studio.
因此,这是对两者都适用的代码:
So here is code that would work for both:
#include <sys/types.h>
#include <sys/stat.h>
#ifndef WIN32
#include <unistd.h>
#endif
#ifdef WIN32
#define stat _stat
#endif
auto filename = "/path/to/file";
struct stat result;
if(stat(filename.c_str(), &result)==0)
{
auto mod_time = result.st_mtime;
...
}
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