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

 

C++

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Symbols index

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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)

 

constexprvoid remove_prefix( size_type n );		(since C++17)

Moves the start of the view forward by n characters.

If n > size() is true, the behavior is undefined.	(until C++26)
If n > size() is true: If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under “observe” evaluation semantic, the behavior is undefined. If the implementation is not hardened, the behavior is undefined.	(since C++26)

Parameters

n

-

number of characters to remove from the start of the view

Complexity

Constant.

Example

Run this code

#include <algorithm>#include <iostream>#include <string_view>   usingnamespace std::literals;   [[nodiscard("a pure function")]]constexprstd::size_t count_substrings(std::string_view hive, conststd::string_view bee){if(hive.empty()|| bee.empty())return 0U;   std::size_t buzz{};while(bee.size()<= hive.size()){constauto pos = hive.find(bee);if(pos == hive.npos)break;++buzz; hive.remove_prefix(pos + bee.size());}return buzz;}   int main(){std::string str =" trim me";std::string_view v = str; v.remove_prefix(std::min(v.find_first_not_of(" "), v.size()));std::cout<<"String: '"<< str <<"'\n"<<"View  : '"<< v <<"'\n";   constexprauto hive{"bee buzz bee buzz bee"};std::cout<<"There are "<< count_substrings(hive, "bee")<<" bees in this hive.\n";}

Output:

String: ' trim me' View  : 'trim me' There are 3 bees in this hive.

See also

remove_suffix

shrinks the view by moving its end backward (public member function)