std::basic_string_view<CharT,Traits>::find_first_of

 

C++

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

 

Strings library

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string_view

Member functions basic_string_view::basic_string_view    basic_string_view::operator= Iterators basic_string_view::beginbasic_string_view::cbegin basic_string_view::endbasic_string_view::cend basic_string_view::rbeginbasic_string_view::crbegin basic_string_view::rendbasic_string_view::crend Capacity basic_string_view::sizebasic_string_view::length basic_string_view::max_size basic_string_view::empty Operations basic_string_view::copy basic_string_view::substr basic_string_view::compare basic_string_view::starts_with (C++20) basic_string_view::ends_with (C++20) basic_string_view::contains (C++23) basic_string_view::find basic_string_view::rfind basic_string_view::find_first_of basic_string_view::find_last_of basic_string_view::find_first_not_of basic_string_view::find_last_not_of

Element access basic_string_view::at basic_string_view::operator[] basic_string_view::front basic_string_view::back basic_string_view::data Modifiers basic_string_view::remove_prefix basic_string_view::remove_suffix basic_string_view::swap Constants basic_string_view::npos Non-member functions operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) operator<< operator""sv Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u8string_view>hash<std::u16string_view>hash<std::u32string_view> (C++20) Deduction guides (C++20)

 

constexpr size_type find_first_of( basic_string_view v, size_type pos = 0 ) const noexcept;	(1)	(since C++17)
constexpr size_type find_first_of( CharT ch, size_type pos = 0 ) const noexcept;	(2)	(since C++17)
constexpr size_type find_first_of( const CharT* s, size_type pos, size_type count ) const;	(3)	(since C++17)
constexpr size_type find_first_of( const CharT* s, size_type pos = 0 ) const;	(4)	(since C++17)

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(ch), 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
ch	-	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>

using namespace std::literals;
constexpr auto N = std::string_view::npos;

constexpr bool is_white_space(const char c)
{
    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')
);

int main() {}

See also

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