std::basic_string::rfind

 

C++

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Regular expressions library (C++11)

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Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Strings library

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basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) 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) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)

Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::replace basic_string::substr basic_string::copy basic_string::resize 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 Constants basic_string::npos

Non-member functions operator+ operator==operator!=operator<operator>operator<=operator>= swap(std::basic_string) operator<<operator>> getline 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) operator""s (C++14) Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string> (C++11)(C++11)(C++11)(C++11)

 

size_type rfind( const basic_string& str, size_type pos = npos ) const;	(1)
size_type rfind( const CharT* s, size_type pos, size_type count ) const;	(2)
size_type rfind( const CharT* s, size_type pos = npos ) const;	(3)
size_type rfind( CharT ch, size_type pos = npos ) const;	(4)
size_type rfind( std::basic_string_view<CharT, Traits> sv,                  size_type pos = npos) const;	(5)	(since C++17)

Finds the last substring equal to the given character sequence. Search begins at pos, i.e. the found substring must not begin in a position following pos. If npos or any value not smaller than size()-1 is passed as pos, whole string will be searched.

1) Finds the last substring equal to str (equality is checked by calling Traits::eq), as if by rfind(std::basic_string_view<CharT, Traits>(str), pos) (since C++17)

2) Finds the last substring equal to the first count characters of the character string pointed to by s. s can include null characters. Equivalent to rfind(std::basic_string(s, count), pos) (until C++17)rfind(std::basic_string_view<CharT, Traits>(s, count), pos) (since C++17)

3) Finds the last substring equal to the character string pointed to by s. The length of the string is determined by the first null character. Equivalent to rfind(std::basic_string(s), pos) (until C++17)rfind(std::basic_string_view<CharT, Traits>(s), pos) (since C++17)

4) Finds the last character ch. Equivalent to rfind(std::basic_string(1,c),pos)

5) Finds the last substring equal to the contents of sv

Parameters

str	-	string to search for
pos	-	position at which to begin searching
count	-	length of substring to search for
s	-	pointer to a character string to search for
ch	-	character to search for
sv	-	std::basic_string_view to search for

Return value

Position of the first character of the found substring or npos if no such substring is found. Note that this is an offset from the start of the string, not the end.

If size() is zero, npos is always returned.

If searching for an empty string (str.size(), count, or strlen(s) is zero) returns pos (the empty string is found immediately) unless pos == npos, in which case returns size().

Exceptions

1-4) (none)	(until C++11)
1,4) noexcept specification:   noexcept    2,3) (none)	(since C++11) (until C++14)
1) noexcept specification:   noexcept    2,3,4) (none)	(since C++14)
5) noexcept specification:   noexcept	(since C++17)

Example

Run this code

#include <string>
#include <iostream>
 
void print(std::string::size_type n, std::string const &s)
{
    if (n == std::string::npos) {
        std::cout << "not found\n";
    } else {
        std::cout << "found: \"" << s.substr(n) << "\" at " << n << '\n';
    }
}
 
int main()
{
    std::string::size_type n;
    std::string const s = "This is a string";
 
    // search backwards from end of string
    n = s.rfind("is");
    print(n, s);
    // search backwards from position 4
    n = s.rfind("is", 4);
    print(n, s);
    // find a single character
    n = s.rfind('s');
    print(n, s);
    // find a single character
    n = s.rfind('q');
    print(n, s);
}

Output:

found: "is a string" at 5
found: "is is a string" at 2
found: "string" at 10
not found

See also

find	find characters in the string (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_of	find last occurrence of characters (public member function)
find_last_not_of	find last absence of characters (public member function)