From cppreference.com
path&operator+=(constpath&p); (1) (since C++17)path&operator+=(conststring_type&str);path&operator+=(std::basic_string_view<value_type>str); (2) (since C++17)path&operator+=(constvalue_type*ptr); (3) (since C++17)path&operator+=(value_typex); (4) (since C++17)template<classCharT>path&operator+=(CharTx); (5) (since C++17)template<classSource>path&operator+=(constSource&source); (6) (since C++17)template<classSource>path&concat(constSource&source); (7) (since C++17)template<classInputIt>path&concat(InputItfirst,InputItlast); (8) (since C++17)Concatenates the current path and the argument
1-3,6,7) Appends path(p).native() to the pathname stored in *this in the native format. This directly manipulates the value of native() and may not be portable between operating systems.
4,5) Same as return*this+=std::basic_string_view(&x,1);.
8) Same as return*this+=path(first,last);.
(6) and (7) participate in overload resolution only if Source and path are not the same type, and either:
Source is a specialization of
or
, or
std::iterator_traits<std::decay_t<Source>>::value_type is valid and denotes a possibly const-qualified encoding character type (char, char8_t, (since C++20)char16_t, char32_t, or wchar_t).
Parameters
p - path to append str - string or string view to append ptr - pointer to the beginning of a null-terminated string to append x - single character to append source -
,
, 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
that specify a multicharacter sequence that represents a path name Type requirements -InputIt must meet the requirements of
. -The value type of InputIt must be one of the encoded character types (char, wchar_t, char16_t and char32_t). -CharT must be one of the encoded character types (char, wchar_t, char16_t and char32_t). Return value
*this
Exceptions
May throw std::bad_alloc if memory allocation fails.
Notes
Unlike with
or
, additional directory separators are never introduced.
Example
Run this code
#include<filesystem>#include<iostream>#include<string>intmain(){std::filesystem::pathp1;// an empty pathp1+="var";// does not insert a separatorstd::cout<<R"("" + "var" --> )"<<p1<<'\n';p1+="lib";// does not insert a separatorstd::cout<<R"("var" + "lib" --> )"<<p1<<'\n';autostr=std::string{"1234567"};p1.concat(std::begin(str)+3,std::end(str)-1);std::cout<<"p1.concat --> "<<p1<<'\n';}Output:
"" + "var" --> "var" "var" + "lib" --> "varlib" p1.concat --> "varlib456" Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++17 the specification of concatenating a single character was ill-formed made well-formed
C++17 constraint that Source cannot be path was missing added See also
appends elements to the path with a directory separator
(public member function)
(C++17)
concatenates two paths with a directory separator
(function)