C++ span容器 连续序列视图实现

std::span

std::vector

std::span

std::span

span

std::vector<int>

int[]

int*

size_t

std::span<int>

#include <iostream>
#include <vector>
#include <array>
#include <span> // C++20

void process_data(std::span<int> data) {
    if (data.empty()) {
        std::cout << "No data to process.\n";
        return;
    }
    std::cout << "Processing " << data.size() << " elements: ";
    for (int x : data) {
        std::cout << x << " ";
    }
    std::cout << "\n";

    // 尝试修改数据 (如果span是非const的)
    if (!data.empty()) {
        data[0] = 99; // span提供非const访问
    }
}

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};
    process_data(vec); // 从vector创建span

    std::cout << "Vector after processing: ";
    for (int x : vec) {
        std::cout << x << " ";
    }
    std::cout << "\n\n";

    int arr[] = {10, 20, 30};
    process_data(arr); // 从C风格数组创建span

    std::cout << "Array after processing: ";
    for (int x : arr) {
        std::cout << x << " ";
    }
    std::cout << "\n\n";

    std::array<int, 2> std_arr = {100, 200};
    process_data(std_arr); // 从std::array创建span

    // 从指针和长度创建span
    int* raw_ptr = new int[3]{50, 60, 70};
    process_data(std::span<int>(raw_ptr, 3));
    delete[] raw_ptr;

    // 创建子span
    std::span<int> full_span = vec;
    std::span<int> sub = full_span.subspan(1, 3); // 从索引1开始，取3个元素
    std::cout << "\nSubspan: ";
    for (int x : sub) {
        std::cout << x << " ";
    }
    std::cout << "\n";

    return 0;
}

std::span

std::vector<int>

const std::vector<int>&

const int* data, size_t size

std::array

int* data, size_t size

size

std::span

size()

operator[]

std::span

std::span

std::span<T>

std::span<const T>

std::vector<T>

std::array<T, N>

span

size_t

std::span

std::span

span

std::vector

span

std::string_view

std::span

span

span

std::span

const

span

std::span<const T>

std::span