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

 

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basic_string

basic_string_view (C++17)

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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 basic_string_view substr( size_type pos =0,                                     size_type count = npos )const;		(since C++17)

Returns a view of the substring [pos, pos + rlen), where rlen is the smaller of count and size()- pos.

Parameters

pos	-	position of the first character
count	-	requested length

Return value

View of the substring [pos, pos + rlen).

Exceptions

std::out_of_range if pos > size().

Complexity

Constant.

Example

Run this code

#include <cstddef>#include <iostream>#include <stdexcept>#include <string_view>   int main(){typedefstd::size_t count_t, pos_t;   constexprstd::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_rangeconst& ex){std::cout<< ex.what()<<'\n';}}

Possible output:

ABCDEF BCDEF CDE EF basic_string_view::substr: __pos (which is 666) > __size (which is 6)

See also

copy	copies characters (public member function)
find	find characters in the view (public member function)
substr	returns a substring (public member function of std::basic_string<CharT,Traits,Allocator>)