C++20中的范围库(ranges)怎么用_C++容器操作与ranges库应用

std::vector<int> vec = {5, 3, 3, 7, 1};
std::sort(vec.begin(), vec.end());
vec.erase(std::unique(vec.begin(), vec.end()), vec.end());

#include <algorithm>
#include <vector>
#include <ranges>
<p>std::vector<int> vec = {5, 3, 3, 7, 1};
std::ranges::sort(vec);
auto [first, last] = std::ranges::unique(vec); // 返回一对迭代器
vec.erase(first, last);</p>

#include <ranges>
#include <iostream>
#include <vector>
<p>std::vector<int> nums = {1, 2, 3, 4, 5, 6};</p>
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                <p>auto result =
nums | std::views::filter([](int n){ return n % 2 == 0; })
| std::views::transform([](int n){ return n * n; });</p><p>for (int x : result) {
std::cout << x << " "; // 输出: 4 16 36
}</p>

auto first_three = nums | std::views::take(3);        // 前三个
auto skip_two   = nums | std::views::drop(2);         // 跳过前两个
auto reversed   = nums | std::views::reverse;         // 反转顺序

#include <string>
#include <vector>
#include <ranges>
#include <algorithm>
#include <cctype>
<p>std::vector<std::string> names = {"Tom", "Alice", "Bob", "Eve", "Charlie"};</p><p>auto processed = names
| std::views::filter([](const std::string& s) { return s.size() > 3; })
| std::views::transform([](std::string s) -> std::string {
std::transform(s.begin(), s.end(), s.begin(), ::toupper);
return s;
});</p><p>for (const auto& name : processed) {
std::cout << name << "\n"; // 输出 ALICE, CHARLIE
}
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