# std::basic_string_view<CharT,Traits>::rfind

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< cpp‎ | string‎ | basic string view

constexpr size_type rfind( basic_string_view v, size_type pos = npos ) const noexcept; | (1) | (since C++17)
constexpr size_type rfind( CharT ch, size_type pos = npos ) const noexcept; | (2) | (since C++17)
constexpr size_type rfind( const CharT* s, size_type pos, size_type count ) const; | (3) | (since C++17)
constexpr size_type rfind( const CharT* s, size_type pos = npos ) const; | (4) | (since C++17)

Finds the last substring that is equal to the given character sequence. The search begins at pos and proceeds from right to left (thus, the found substring, if any, cannot begin in a position following pos). If npos or any value not smaller than size() - 1 is passed as pos, the whole string will be searched.

1) Finds the last occurrence of v in this view, starting at position pos.
2) Equivalent to rfind(basic_string_view( std::addressof (ch), 1), pos).
3) Equivalent to rfind(basic_string_view(s, count), pos).
4) Equivalent to rfind(basic_string_view(s), pos).

### Parameters

v | - | view to search for
pos | - | position at which to start the search
count | - | length of substring to search for
s | - | pointer to a character string to search for
ch | - | character to search for

### Return value

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

### Complexity

O(size() * v.size()) at worst.

### Example

Run this code

    #include <string_view>

    int main()
    {
        using namespace std::literals;
        constexpr auto N = std::string_view::npos;

        static_assert(true
            && (6 == "AB AB AB"sv.rfind("AB"))
            && (6 == "AB AB AB"sv.rfind("ABCD", N, 2))
            && (3 == "AB AB AB"sv.rfind("AB", 5))
            && (0 == "AB CD EF"sv.rfind("AB", 0))
            && (2 == "B AB AB "sv.rfind("AB", 2))
            && (N == "B AB AB "sv.rfind("AB", 1))
            && (5 == "B AB AB "sv.rfind('A'))
            && (4 == "AB AB AB"sv.rfind('B', 4))
            && (N == "AB AB AB"sv.rfind('C'))
        );
    }

### See also

find | find characters in the view (public member function)
find_first_of | find first occurrence of characters (public member function)
find_last_of | find last 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)
rfind | find the last occurrence of a substring (public member function of `std::basic_string<CharT,Traits,Allocator>`)

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