std::ranges::remove, std::ranges::remove_if

Example

main: () = {
    v1: std::string = ("No - Diagnostic - Required");
    std::println("\"{}\" (v1, size: {})", v1, v1.size());

    ret:= std::ranges::remove(v1, ' ');
    std::println("\"{}\" (v1 after `remove`, size: {})", v1, v1.size());
    std::println(" {}", std::string(std::distance(v1.begin(), ret.begin()) as size_t, '^'));

    _ = v1.erase(ret.begin(), ret.end());
    std::println("\"{}\" (v1 after `erase`, size: {})", v1, v1.size());
    std::println();

    // remove_if with custom unary predicate:
    rm:= :(c: char) !std::isupper(c);
    v2: std::string = ("Substitution Failure Is Not An Error");
    std::println("\"{}\" (v2, size: {})", v2, v2.size());
    remove_result:= std::ranges::remove_if(v2, rm);
    std::println("\"{}\" (v2 after `remove_if`, size: {})", v2, v2.size());
    std::println(" {}", std::string(std::distance(v2.begin(), remove_result.begin()) as size_t, '^'));

    _ = v2.erase(remove_result.begin(), remove_result.end());
    std::println("\"{}\" (v2 after `erase`, size: {})", v2, v2.size());
    std::println();

    // creating a view into a container that is modified by `remove_if`:
    using std::string_literals::_;
    for ("Small Object Optimization"s, "Non-Type Template Parameter"s) do (copy s) {
        std::cout << std::quoted(s) << " => "
            << std::string_view(begin(s), std::ranges::remove_if(s, rm).begin()) << '\n';
        _ = s;
    }

    nums: std::vector = (
        :std::complex<double>=(2, 2),
        :std::complex<double>=(1, 3),
        :std::complex<double>=(4, 8));
    e:= std::ranges::remove(nums, std::complex<double>(1, 3));
    _ = nums.erase(e.begin(), e.end());

    assert(nums.size() == 2
        && nums[0] == std::complex<double>(2, 2)
        && nums[1] == std::complex<double>(4, 8));
}

Output

"No - Diagnostic - Required" (v1, size: 26)
"No-Diagnostic-Requiredired" (v1 after `remove`, size: 26)
 ^^^^^^^^^^^^^^^^^^^^^^
"No-Diagnostic-Required" (v1 after `erase`, size: 22)

"Substitution Failure Is Not An Error" (v2, size: 36)
"SFINAEtution Failure Is Not An Error" (v2 after `remove_if`, size: 36)
 ^^^^^^
"SFINAE" (v2 after `erase`, size: 6)

"Small Object Optimization" => SOO
"Non-Type Template Parameter" => NTTP