NAME

std::filesystem::path::replace_extension - std::filesystem::path::replace_extension

Synopsis

path& replace_extension( const path& replacement = path() ); (since C++17)

Replaces the extension with replacement or removes it when the default value of
replacement is used.

Firstly, if this path has an extension(), it is removed from the generic-format view
of the pathname.

Then, a dot character is appended to the generic-format view of the pathname, if
replacement is not empty and does not begin with a dot character.

Then replacement is appended as if by operator+=(replacement).

Parameters

replacement - the extension to replace with

Return value

*this

Exceptions

May throw implementation-defined exceptions.

Notes

The type of replacement is std::filesystem::path even though it is not intended to
represent an object on the file system in order to correctly account for the
filesystem character encoding.

Example

// Run this code

#include <filesystem>
#include <iomanip>
#include <iostream>
#include <utility>
namespace fs = std::filesystem;

int main()
{
std::cout << "Path: Ext: Result:\n" << std::left;
for (const auto& [path, extension] : {
std::make_pair( "/foo/bar.jpg", ".png" ),
std::make_pair( "/foo/bar.jpg", "png" ),
std::make_pair( "/foo/bar.jpg", "." ),
std::make_pair( "/foo/bar.jpg", "" ),
std::make_pair( "/foo/bar." , "png" ),
std::make_pair( "/foo/bar" , ".png" ),
std::make_pair( "/foo/bar" , "png" ),
std::make_pair( "/foo/bar" , "." ),
std::make_pair( "/foo/bar" , "" ),
std::make_pair( "/foo/." , ".png" ),
std::make_pair( "/foo/." , "png" ),
std::make_pair( "/foo/." , "." ),
std::make_pair( "/foo/." , "" ),
std::make_pair( "/foo/" , ".png" ),
std::make_pair( "/foo/" , "png" ), })
{
fs::path p = path, e = extension;
std::cout << std::setw(18) << p << std::setw(11) << e;
p.replace_extension(e);
std::cout << p << '\n';
}
}

Output:

Path: Ext: Result:
"/foo/bar.jpg" ".png" "/foo/bar.png"
"/foo/bar.jpg" "png" "/foo/bar.png"
"/foo/bar.jpg" "." "/foo/bar."
"/foo/bar.jpg" "" "/foo/bar"
"/foo/bar." "png" "/foo/bar.png"
"/foo/bar" ".png" "/foo/bar.png"
"/foo/bar" "png" "/foo/bar.png"
"/foo/bar" "." "/foo/bar."
"/foo/bar" "" "/foo/bar"
"/foo/." ".png" "/foo/..png"
"/foo/." "png" "/foo/..png"
"/foo/." "." "/foo/.."
"/foo/." "" "/foo/."
"/foo/" ".png" "/foo/.png"
"/foo/" "png" "/foo/.png"