std::basic_string_view<CharT,Traits>::substr
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< cpp | string | basic string view
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std::basic_string_view
basic_string_view::substr
(C++20)
(C++20)
(C++23)
Constants
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Deduction guides (C++20)
constexpr basic_string_view substr( size_type pos = 0,
size_type count = npos ) const;
(since C++17)
size_type count = npos ) const;
Returns a view of the substring [pos, pos + rlen), where rlen is the smaller of count and size() - pos.
[edit] Parameters
pos
-
position of the first character
count
-
requested length
[edit] Return value
View of the substring [pos, pos + rlen).
[edit] Exceptions
std::out_of_range if pos > size().
[edit] Complexity
Constant.
[edit] Example
Run this code
#include <cstddef> #include <iostream> #include <stdexcept> #include <string_view> int main() { typedef std::size_t count_t, pos_t; constexpr std::string_view data{"ABCDEF"}; std::cout << data.substr() << '\n'; // ABCDEF, i.e. data[0, 5] that is [0, 6) std::cout << data.substr(pos_t(1)) << '\n'; // BCDEF, i.e. [1, 6) std::cout << data.substr(pos_t(2), count_t(3)) << '\n'; // CDE, i.e. [2, 2 + 3) std::cout << data.substr(pos_t(4), count_t(42)) << '\n'; // EF, i.e. [4, 6) try { [[maybe_unused]] auto sub = data.substr(pos_t(666), count_t(1)); // throws: pos > size() } catch (std::out_of_range const& ex) { std::cout << ex.what() << '\n'; } }
Possible output:
ABCDEF BCDEF CDE EF basic_string_view::substr: __pos (which is 666) > __size (which is 6)