std::filesystem::path::compare

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator      filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

std::filesystem::path

Constants
path::native_formatpath::generic_formatpath::auto_format
Member functions
path::path path::~path path::operator= path::assign path::appendpath::operator/= path::concatpath::operator+= path::clear path::make_preferred path::remove_filename path::replace_filename path::replace_extension      path::swap path::compare path::beginpath::end	path::c_strpath::nativepath::operator string_type path::stringpath::u8stringpath::u16stringpath::u32stringpath::wstring path::generic_stringpath::generic_u8stringpath::generic_u16stringpath::generic_u32stringpath::generic_wstring path::lexically_normalpath::lexically_relativepath::lexically_proximate
Path decomposition
path::root_name path::root_directory path::root_path path::relative_path path::parent_path path::filename path::stem path::extension path::empty	path::has_root_pathpath::has_root_namepath::has_root_directorypath::has_relative_pathpath::has_parent_pathpath::has_filenamepath::has_stempath::has_extension path::is_absolutepath::is_relative
Non-member functions
operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)	operator/ operator<<operator>> swap(std::filesystem::path) hash_value u8path
Helper Classes
hash<std::filesystem::path>
formatter<std::filesystem::path> (C++26)

 

int compare( const path& p ) const;	(1)	(since C++17)
int compare( const string_type& str ) const; int compare( const std::basic_string_view<value_type>& str ) const;	(2)	(since C++17)
int compare( const value_type* s ) const;	(3)	(since C++17)

Compares the lexical representations of the path and another path.

1) Returns a value less than, equal to or greater than 0 if the native representation of the path (native()) is respectively lexicographically less than, equal to or greater than the native representation of p (p.native()). Comparison is performed element-wise, as if by iterating both paths from begin() to end().

2) Equivalent to compare(path(str)).

3) Equivalent to compare(path(s)).

Parameters

p	-	a path to compare to
str	-	a string or string view representing path to compare to
s	-	a null-terminated string representing path to compare to

Return value

A value less than 0 if the path is lexicographically less than the given path.

A value equal to 0 if the path is lexicographically equal to the given path.

A value greater than 0 if the path is lexicographically greater than the given path.

Exceptions

1)

noexcept specification:  

noexcept

  

2-3) (none)

Notes

For two-way comparisons, binary operators may be more suitable.

Example

Run this code

#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
void demo(int rc, fs::path p1, fs::path p2) {
    if(rc < 0) std::cout << p1 << " < " << p2 << '\n';
    else if(rc > 0) std::cout << p1 << " > "  << p2 << '\n';
    else if(rc == 0) std::cout << p1 << "==" << p2 << '\n';
}
int main() {
    fs::path p1 = "/a/b/"; // as if "a/b/." for lexicographical iteration
    fs::path p2 = "/a/b/#";
    demo(p1.compare(p2), p1, p2);
    demo(p1.compare("a/b/_"), p1, "a/b/_");
}

Output:

"/a/b/" > "/a/b/#"
"/a/b/" < "a/b/_"

See also

operator==operator!=operator<operator<=operator>operator>=operator<=> (C++17)(C++17)(until C++20)(C++17)(until C++20)(C++17)(until C++20)(C++17)(until C++20)(C++17)(until C++20)(C++20)

lexicographically compares two paths (function)