std::string_view rfind() method

od C++17

// (1) Const version only
size_type rfind( const basic_string& str, size_type pos = 0 ) const noexcept;

// (2) Const version only
size_type rfind( const CharT* s, size_type pos, size_type count ) const;

// (3) Const version only
size_type rfind( const CharT* s, size_type pos = 0 ) const;

// (4) Const version only
size_type rfind( CharT ch, size_type pos = 0 ) const noexcept;

// (5) Const version only
template < class StringViewLike >
size_type rfind( const StringViewLike& t, size_type pos = 0 ) const noexcept(/* see below */);

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 occurrence of v in this view, starting at position pos.
• (2) Equivalent to rfind(basic_string_view(std::addressof(c), 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.

important

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Exceptions

(none)

Example

#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))
        && (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'))
    );
}