NAME¶

std::filesystem::relative,std::filesystem::proximate - std::filesystem::relative,std::filesystem::proximate

Synopsis¶

Defined in header <filesystem>
path relative( const std::filesystem::path& p, (1) (since C++17)
std::error_code& ec );
path relative( const std::filesystem::path& p,

const std::filesystem::path& base =
std::filesystem::current_path()); (2) (since C++17)
path relative( const std::filesystem::path& p,
const std::filesystem::path& base,

std::error_code& ec );
path proximate( const std::filesystem::path& p, (3) (since C++17)
std::error_code& ec );
path proximate( const std::filesystem::path& p,

const std::filesystem::path& base =
std::filesystem::current_path()); (4) (since C++17)
path proximate( const std::filesystem::path& p,
const std::filesystem::path& base,

std::error_code& ec );

1) Returns relative(p, current_path(), ec)
2) Returns p made relative to base. Resolves symlinks and normalizes both p and base
before other processing. Effectively returns
std::filesystem::weakly_canonical(p).lexically_relative(std::filesystem::weakly_canonical(base))
or std::filesystem::weakly_canonical(p,
ec).lexically_relative(std::filesystem::weakly_canonical(base, ec)), except the
error code form returns path() at the first error occurrence, if any.
3) Returns proximate(p, current_path(), ec)
4) Effectively returns
std::filesystem::weakly_canonical(p).lexically_proximate(std::filesystem::weakly_canonical(base))
or std::filesystem::weakly_canonical(p,
ec).lexically_proximate(std::filesystem::weakly_canonical(base, ec)), except the
error code form returns path() at the first error occurrence, if any.

Parameters¶

p - an existing path
base - base path, against which p will be made relative/proximate
ec - error code to store error status to

Return value¶

1) p made relative against base.
2) p made proximate against base

Exceptions¶

The overload that does not take a std::error_code& parameter throws
filesystem::filesystem_error on underlying OS API errors, constructed with p as the
first path argument, base as the second path argument, and the OS error code as the
error code argument. The overload taking a std::error_code& parameter sets it to the
OS API error code if an OS API call fails, and executes ec.clear() if no errors
occur. Any overload not marked noexcept may throw std::bad_alloc if memory
allocation fails.

Example¶

// Run this code

#include <iostream>
#include <filesystem>

void show(std::filesystem::path x, std::filesystem::path y)
{
std::cout << "x:\t\t " << x << "\ny:\t\t " << y << '\n'
<< "relative(x, y): "
<< std::filesystem::relative(x, y) << '\n'
<< "proximate(x, y): "
<< std::filesystem::proximate(x, y) << "\n\n";
}

int main()
{
show("/a/b/c", "/a/b");
show("/a/c", "/a/b");
show("c", "/a/b");
show("/a/b", "c");
}

Possible output:¶

x: "/a/b/c"
y: "/a/b"
relative(x, y): "c"
proximate(x, y): "c"

x: "/a/c"
y: "/a/b"
relative(x, y): "../c"
proximate(x, y): "../c"

x: "c"
y: "/a/b"
relative(x, y): ""
proximate(x, y): "c"

x: "/a/b"
y: "c"
relative(x, y): ""
proximate(x, y): "/a/b"

See also¶

path represents a path
(C++17) (class)
absolute composes an absolute path
(C++17) (function)
canonical composes a canonical path
weakly_canonical (function)
(C++17)
lexically_normal converts path to normal form
lexically_relative converts path to relative form
lexically_proximate converts path to proximate form
(public member function of std::filesystem::path)