std::basic_string_view<CharT,Traits>:: find_first_of
From cppreference.com
<
cpp
|
string
|
basic string view
|
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 characters in the view
(public member function) |
|
|
find the last occurrence of a substring
(public member function) |
|
|
find last occurrence of characters
(public member function) |
|
|
find first absence of characters
(public member function) |
|
|
find last absence of characters
(public member function) |
|
|
find first occurrence of characters
(public member function of
std::basic_string<CharT,Traits,Allocator>
)
|