std::filesystem::path::compare

int compare( const path& p ) const;	(1)	(since C++17)
int compare( const string_type& str ) const; int compare( 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/_"

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
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Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications