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# std::filesystem::path::append, std::filesystem::path::operator/=

From cppreference.com
< cpp‎ | filesystem‎ | path

path& operator/=(const path& p); | (1) | (since C++17)
template< class Source > path& operator/=( const Source& source ); | (2) | (since C++17)
template< class Source > path& append( const Source& source ); | (3) | (since C++17)
template< class InputIt > path& append( InputIt first, InputIt last ); | (4) | (since C++17)

1) First, appends the preferred directory separator to this, except if any of the following conditions is true:
* the separator would be redundant (*this already ends with a separator)
* *this is empty, or adding it would turn a relative path to an absolute path in some other way
* `p` is an empty path.
* p.native() begins with a directory separator.
Then, appends p.native() to the pathname maintained by *this
The behavior is undefined if p.has_root_name() is true.
2,3) Same as (1), but accepts any std::basic_string, std::basic_string_view, null-terminated multicharacter string, or an input iterator pointing to a null-terminated multicharacter sequence. Equivalent to return operator/=(path(source));.
4) Same as (1), but accepts any iterator pair that designates a multicharacter string. Equivalent to return operator/=(path(first, last));

### [edit] Parameters

p | - | pathname to append
source | - | std::basic_string, std::basic_string_view, null-terminated multicharacter string, or an input iterator pointing to a null-terminated multicharacter sequence, which represents a path name (either in portable or in native format)
first, last | - | pair of `InputIterator`s that specify a multicharacter sequence that represents a path name
Type requirements
- `InputIt` must meet the requirements of `InputIterator`.
- The value type of `InputIt` must be one of the encoded character types (char, wchar_t, char16_t and char32_t)

### [edit] Return value

*this

### [edit] Exceptions

May throw `filesystem_error` on underlying OS API errors or std::bad_alloc if memory allocation fails.

### [edit] Example

Run this code

    #include <iostream>
    #include <filesystem>
    namespace fs = std::filesystem;
    int main() {
        fs::path p1 = "C:";
        p1 /= "Users"; // does not insert a separator
        std::cout << "\"C:\" / \"Users\" == " << p1 << '\n';
        p1 /= "batman"; // inserts fs::path::preferred_separator, '\' on Windows
        std::cout << "\"C:\" / \"Users\" / \"batman\" == " << p1 << '\n';
    }

Possible output:

    "C:" / "Users" == "C:Users"
    "C:" / "Users" / "batman" == "C:Users\batman"

### [edit] See also

concat operator+= | concatenates two paths without introducing a directory separator (public member function) [edit]
operator/ | concatenates two paths with a directory separator (function) [edit]

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