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std::basic_...ind_first_of(3) C++ Standard Libarystd::basic_...ind_first_of(3) NAME std::basic_string_view::find_first_of - std::ba- sic_string_view::find_first_of Synopsis constexpr size_type find_first_of( basic_string_view v, size_type (1) (since C++17) pos = 0 ) const noexcept; constexpr size_type find_first_of( CharT c, size_type pos = 0 ) (2) (since C++17) const noexcept; constexpr size_type find_first_of( const CharT* s, size_type pos, (3) (since C++17) size_type count ) const; constexpr size_type find_first_of( const CharT* s, size_type pos = (4) (since C++17) 0 ) const; Finds the first character equal to any of the characters in the given character sequence. 1) Finds the first occurrence of any of the characters of v in this view, starting at position pos. 2) Equivalent to find_first_of(basic_string_view(std::addressof(c), 1), pos). 3) Equivalent to find_first_of(basic_string_view(s, count), pos). 4) Equivalent to find_first_of(basic_string_view(s), pos). Parameters v - view to search for pos - position at which to start the search count - length of the string of characters to search for s - pointer to a string of characters to search for c - character to search for Return value Position of the first occurrence of any character of the substring, or npos if no such character is found. Complexity O(size() * v.size()) at worst. Example // Run this code #include <string_view> #include <iostream> int main() { using namespace std::literals; constexpr auto N = std::string_view::npos; auto is_white_space = [](const char c) noexcept { return " \t\n\f\r\v"sv.find_first_of(c) != N; }; static_assert( 1 == "alignas"sv.find_first_of("klmn"sv) && // N == "alignof"sv.find_first_of("wxyz"sv) && // 3 == "concept"sv.find_first_of("bcde"sv, /* pos= */ 1) && // N == "consteval"sv.find_first_of("oxyz"sv, /* pos= */ 2) && // 6 == "constexpr"sv.find_first_of('x') && // N == "constinit"sv.find_first_of('x') && // 6 == "const_cast"sv.find_first_of('c', /* pos= */ 4) && // N == "continue"sv.find_first_of('c', /* pos= */ 42) && // 5 == "co_await"sv.find_first_of("cba", /* pos= */ 4) && // 7 == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */ 2) && // N == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */ 1) && // is_white_space(' ') && is_white_space('\r') && !is_white_space('\a') ); std::cout << "All tests passed.\n"; } Output: All tests passed. See also find find characters in the view (C++17) (public member function) rfind find the last occurrence of a substring (C++17) (public member function) find_last_of find last occurrence of characters (C++17) (public member function) find_first_not_of find first absence of characters (C++17) (public member function) find_last_not_of find last absence of characters (C++17) (public member function) find first occurrence of characters find_first_of (public member function of std::basic_string<CharT,Traits,Allocator>) http://cppreference.com 2022.07.31 std::basic_...ind_first_of(3)
NAME | Synopsis | Parameters | Return value | Complexity | Example | Output: | See also
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