std::erase,...asic_string)(3)

🎀 std::erase,...asic_string)(3) — C++ Standard Libary 🎀

okay bestie, this is the page for std::erase,std::erase_if(std::basic_string) from the C++ Standard Libary, and it’s literally the “delete the things you don’t want from a string” duo. no cap, the vibes are useful. 💖

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💅 NAME 💅

std::erase,std::erase_if(std::basic_string) — yup, that’s the name twice, bestie: std::erase,std::erase_if(std::basic_string). iconic behavior, honestly. 🫶

✨ Synopsis ✨

Defined in header <string> — write that down. 📝

template< class CharT, class Traits, class Alloc, class U >

constexpr std::basic_string<CharT, Traits, Alloc>::size_type
       (since C++20)
                                                                                 (until
       C++26)
              erase( std::basic_string<CharT, Traits, Alloc>& c, const
          U& value );
          template< class CharT, class Traits, class Alloc, class U =
          CharT >

          constexpr std::basic_string<CharT, Traits, Alloc>::size_type   (1)
       (since C++26)

              erase( std::basic_string<CharT, Traits, Alloc>& c, const
          U& value );
          template< class CharT, class Traits, class Alloc, class Pred >

          constexpr std::basic_string<CharT, Traits, Alloc>::size_type
       (2) (since C++20)

              erase_if( std::basic_string<CharT, Traits, Alloc>& c, Pred
          pred );

1) Erases all elements that compare equal to value from the container. Equivalent to

auto it = std::remove(c.begin(), c.end(), value);
auto r = c.end() - it;
c.erase(it, c.end());
return r;

2) Erases all elements that satisfy the predicate pred from the container. Equivalent to

auto it = std::remove_if(c.begin(), c.end(), pred);
auto r = c.end() - it;
c.erase(it, c.end());
return r;

💖 Parameters 💖

• c — container from which to erase.
• value — value to be removed.
• pred — unary predicate which returns true if the element should be erased.
  • The expression pred(v) must be convertible to bool for every argument v of type (possibly const) CharT, regardless of value category, and must not modify v.
  • Thus, a parameter type of CharT& is not allowed, nor is CharT unless for CharT a move is equivalent to a copy (since C++11).

This is the part where the compiler is like “bestie, read the predicate rules,” so don’t try to sneak in a CharT& unless you want chaos. 💀

🌈 Return value 🌈

The number of erased elements. That’s it — it’s literally counting the deleted girlies. 💅

🦋 Complexity 🦋

Linear. Periodt. ✨

🧚 Notes 🧚

Here’s the feature-test macro tea:

• Feature-test macro: __cpp_lib_algorithm_default_value_type
  • Value: 202403
  • Std: (C++26)
  • Feature: List-initialization for algorithm (1)

🍓 Example 🍓

Run this code, bestie:

// Run this code

#include <iomanip>
#include <iostream>
#include <string>

int main()
{
    std::string word{"startling"};
    std::cout << "Initially, word = " << std::quoted(word) << '\n';

    std::erase(word, 'l');
    std::cout << "After erase 'l': " << std::quoted(word) << '\n';

    auto erased = std::erase_if(word, [](char x)
    {
        return x == 'a' or x == 'r' or x == 't';
    });

    std::cout << "After erase all 'a', 'r', and 't': " <<
std::quoted(word) << '\n';
    std::cout << "Erased symbols count: " << erased << '\n';
}

🌸 Output 🌸

Initially, word = "startling"
After erase 'l', word = "starting"
After erase all 'a', 'r', and 't': "sing"
Erased symbols count: 4

👑 See also 👑

• remove — removes elements satisfying specific criteria.
• remove_if — function template.

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💖 That’s the tea! Source: http://cppreference.com · version/date: 2024.06.10 · page: std::erase,...asic_string)(3) 💖