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

From cppreference.com

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)
Diagnostics library
Memory management library
Metaprogramming library(C++11)
General utilities library
Containers library
Iterators library
Ranges library(C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library(C++17)
Concurrency support library(C++11)
Execution control library(C++26)
Technical specifications
Symbols index
External libraries

[edit]

Strings library

Classes
basic_string
basic_string_view (C++17)
char_traits

[edit]

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 (C++11)
basic_string::endbasic_string::cend (C++11)
basic_string::rbeginbasic_string::crbegin (C++11)
basic_string::rendbasic_string::crend (C++11)
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

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
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*)
Operations
basic_string::compare
basic_string::starts_with (C++20)
basic_string::ends_with (C++20)
basic_string::contains (C++23)
basic_string::substr

swap(std::basic_string)

erase(std::basic_string)erase_if(std::basic_string)

(C++20)(C++20)

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 conversions

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)

Literals

operator""s

(C++14)

Helper classes

hash<std::basic_string>

(C++11)

Deduction guides(C++17)

[edit]

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

Finds the last character equal to none of the characters in the given character sequence. The search considers only the range[0, pos]. If all characters in the range can be found in the given character sequence,npos will be returned.

1) Finds the last character equal to none of characters instr.

2) Finds the last character equal to none of characters in the range[s, s+ count). This range can include null characters.

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

3) Finds the last character equal to none of characters in character string pointed to bys. The length of the string is determined by the first null character usingTraits::length(s).

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

4) Finds the last character not equal toch.

5) Implicitly convertst to a string viewsv as if bystd::basic_string_view<CharT, Traits> sv= t;, then finds the last character equal to none of characters insv.

This overload participates in overload resolution only ifstd::is_convertible_v<const StringViewLike&,
std::basic_string_view<CharT, Traits>> istrue andstd::is_convertible_v<const StringViewLike&,const CharT*> isfalse.

In all cases, equality is checked by callingTraits::eq.

[edit]Parameters

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

[edit]Return value

Position of the found character ornpos if no such character is found.

[edit]Exceptions

1,4) Throws nothing.

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).

[edit]Example

Run this code

#include <iostream>#include <string> void show_pos(conststd::string& str, std::string::size_type found){if(found!=std::string::npos)std::cout<<'['<< found<<"] =\'"<< str[found]<<"\'\n";elsestd::cout<<"not found\n";} int main(){std::string str{"abc_123"};charconst* skip_set{"0123456789"};    std::string::size_type str_last_pos{std::string::npos};     show_pos(str, str.find_last_not_of(skip_set));// [3] = '_'     str_last_pos=2;    show_pos(str, str.find_last_not_of(skip_set, str_last_pos));// [2] = 'c'     str_last_pos=2;    show_pos(str, str.find_last_not_of('c', str_last_pos));// [1] = 'b' constchar arr[]{'3','4','5'};    show_pos(str, str.find_last_not_of(arr));// [5] = '2'     str_last_pos=2;    std::string::size_type skip_set_size{4};    show_pos(str, str.find_last_not_of(skip_set,                                       str_last_pos,                                       skip_set_size));// [2] = 'c'     show_pos(str, str.find_last_not_of("abc"));// [6] = '3'     str_last_pos=2;    show_pos(str, str.find_last_not_of("abc", str_last_pos));// not found}

Output:

[3] = '_'[2] = 'c'[1] = 'b'[5] = '2'[2] = 'c'[6] = '3'not found

[edit]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 returnnpos ifpos>= 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 accidentally dropped by LWG2064/LWG2946	restored

[edit]See also

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