std::basic_string<CharT,Traits,Allocator>::find_last_of

 

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)

Technical specifications

Symbols index

External libraries

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (DR*) basic_string::endbasic_string::cend (DR*) basic_string::rbeginbasic_string::crbegin (DR*) basic_string::rendbasic_string::crend (DR*) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)   basic_string::swap

Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Operations basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::substr Constants basic_string::npos Deduction guides (C++17) Non-member functions operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversion stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Helper classes hash<std::basic_string> (C++11)

 

	(1)
size_type find_last_of( const basic_string& str,                         size_type pos = npos ) const;			(until C++11)
size_type find_last_of( const basic_string& str,                         size_type pos = npos ) const noexcept;			(since C++11) (until C++20)
constexpr size_type find_last_of( const basic_string& str,                                   size_type pos = npos ) const noexcept;			(since C++20)
		(2)
size_type find_last_of( const CharT* s,                         size_type pos, size_type count ) const;				(until C++11)
constexpr size_type find_last_of( const CharT* s,                                   size_type pos, size_type count ) const;				(since C++11)
			(3)
size_type find_last_of( const CharT* s, size_type pos = npos ) const;					(until C++20)
constexpr size_type find_last_of( const CharT* s,                                   size_type pos = npos ) const;					(since C++20)
				(4)
size_type find_last_of( CharT ch, size_type pos = npos ) const;						(until C++11)
size_type find_last_of( CharT ch, size_type pos = npos ) const noexcept;						(since C++11) (until C++20)
constexpr size_type find_last_of( CharT ch,                                   size_type pos = npos ) const noexcept;						(since C++20)
					(5)
template< class StringViewLike > size_type     find_last_of( const StringViewLike& t,                   size_type pos = npos ) const noexcept(/* see below */);							(since C++17) (until C++20)
template< class StringViewLike > constexpr size_type     find_last_of( const StringViewLike& t,                   size_type pos = npos ) const noexcept(/* see below */);							(since C++20)

Finds the last character equal to one of characters in the given character sequence. The exact search algorithm is not specified. The search considers only the range [​0​, pos]. If none of the characters in the given character sequence is present in the range, npos will be returned.

1) Finds the last character equal to one of characters in str.

2) Finds the last character equal to one of characters in range [s, s + count). This range can include null characters.

If [s, s + count) is not a valid range, the behavior is undefined.

3) Finds the last character equal to one of characters in character string pointed to by s. The length of the string is determined by the first null character using Traits::length(s).

If [s, s + Traits::length(s)) is not a valid range, the behavior is undefined.

4) Finds the last character equal to ch.

5) Implicitly converts t to a string view sv as if by std::basic_string_view<CharT, Traits> sv = t;, then finds the last character equal to one of characters in sv.

This overload participates in overload resolution only if std::is_convertible_v<const StringViewLike&,
                      std::basic_string_view<CharT, Traits>> is true and std::is_convertible_v<const StringViewLike&, const CharT*> is false.

In all cases, equality is checked by calling Traits::eq.

Parameters

str	-	string identifying characters to search for
pos	-	position at which the search is to finish
count	-	length of character string identifying characters to search for
s	-	pointer to a character string identifying characters to search for
ch	-	character to search for
t	-	object (convertible to std::basic_string_view) identifying characters to search for

Return value

Position of the found character or npos if no such character is found.

Exceptions

1,4) Throws nothing.

5)

noexcept specification:  

noexcept(std::is_nothrow_convertible_v<const T&, std::basic_string_view<CharT, Traits>>)

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

Example

Run this code

#include <iostream>
#include <string>
 
int main()
{
    const std::string path = "/root/config";
    auto const pos = path.find_last_of('/');
    const auto leaf = path.substr(pos + 1);
 
    std::cout << leaf << '\n';
}

Output:

config

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 141	C++98	overload (1) could only return npos if pos >= size()	the search range is [​0​, size()) in this case
LWG 847	C++98	there was no exception safety guarantee	added strong exception safety guarantee
LWG 2064	C++11	overloads (3,4) were noexcept	removed
LWG 2946	C++17	overload (5) caused ambiguity in some cases	avoided by making it a template
P1148R0	C++11 C++17	noexcept for overloads (4,5) were accidently dropped by LWG2064/LWG2946	restored

See also

find	finds the first occurrence of the given substring (public member function)
rfind	find the last occurrence of a substring (public member function)
find_first_of	find first occurrence of characters (public member function)
find_first_not_of	find first absence of characters (public member function)
find_last_not_of	find last absence of characters (public member function)
find_last_of (C++17)	find last occurrence of characters (public member function of std::basic_string_view<CharT,Traits>)