Detect whether path is absolute or relative
Using C++, I need to detect whether given path (file name) is absolute or 开发者_如何学Gorelative. I can use Windows API, but don't want to use third-party libraries like Boost, since I need this solution in small Windows application without expernal dependencies.
The Windows API has PathIsRelative
. It is defined as:
BOOL PathIsRelative(
_In_ LPCTSTR lpszPath
);
Beginning with C++14/C++17 you can use is_absolute()
and is_relative()
from the filesystem library
#include <filesystem> // C++17 (or Microsoft-specific implementation in C++14)
std::string winPathString = "C:/tmp";
std::filesystem::path path(winPathString); // Construct the path from a string.
if (path.is_absolute()) {
// Arriving here if winPathString = "C:/tmp".
}
if (path.is_relative()) {
// Arriving here if winPathString = "".
// Arriving here if winPathString = "tmp".
// Arriving here in windows if winPathString = "/tmp". (see quote below)
}
The path "/" is absolute on a POSIX OS, but is relative on Windows.
In C++14 use std::experimental::filesystem
#include <experimental/filesystem> // C++14
std::experimental::filesystem::path path(winPathString); // Construct the path from a string.
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