NAME¶

std::basic_string_view::remove_prefix - std::basic_string_view::remove_prefix

Synopsis¶

constexpr void remove_prefix( size_type n ); (since C++17)

Moves the start of the view forward by n characters.

The behavior is undefined if n > size().

Parameters¶

n - number of characters to remove from the start of the view

Return value¶

(none)

Complexity¶

Constant.

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <string_view>

using namespace std::literals;

[[nodiscard("a pure function")]]
constexpr std::size_t count_substrings(std::string_view hive, std::string_view const bee)
{
if (hive.empty() || bee.empty())
return 0U;

std::size_t buzz{};
while (bee.size() <= hive.size())
{
const auto 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";

constexpr auto 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)