cpp 自定义类实现for (:)遍历

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原创最新推荐文章于 2026-04-26 14:15:26 发布 233 阅读 AI 写同款· GEO 优化 ›

C++范围for循环：从语法原理到实战应用全解析在C++编程中，容器遍历是基础且高频的操作。传统基于下标的for循环虽然功能强大，但代码冗长且容易引入下标越界等错误。范围for循环（Range-based for loop）作为C++11引入的语法糖，其核心原理是通过自动调用容器的begin()和end()函数获取迭代器，在编译期展开为等价的迭代器循环，从而让开发者更专注于业务逻辑而非迭代细节。这一特性体现了声明式编程思想，显著提升了代码的可读性和安全性。在工程实践中，范围for循环与STL容器（如vector、map）无缝集成，通过传引用方式避免不必要阅读详情

#include "pch.h"
#include <cstddef>
#include <iostream>
#include <stdexcept>

template <typename T>
class CustomVector {
private:
    T* data;
    size_t size;
    size_t capacity;

public:
    // Iterator class
    class Iterator {
    private:
        T* ptr;
    public:
        Iterator(T* p) : ptr(p) {}

        T& operator*() { return *ptr; }
        T* operator->() { return ptr; }

        Iterator& operator++() { ++ptr; return *this; }
        Iterator operator++(int) { Iterator tmp = *this; ++ptr; return tmp; }

        bool operator==(const Iterator& other) const { return ptr == other.ptr; }
        bool operator!=(const Iterator& other) const { return ptr != other.ptr; }
    };

    CustomVector() : data(nullptr), size(0), capacity(0) {}

    ~CustomVector() { delete[] data; }

    void push_back(const T& value) {
        if (size == capacity) {
            size_t new_capacity = capacity == 0 ? 1 : capacity * 2;
            T* new_data = new T[new_capacity];
            for (size_t i = 0; i < size; ++i) {
                new_data[i] = data[i];
            }
            delete[] data;
            data = new_data;
            capacity = new_capacity;
        }
        data[size++] = value;
    }

    T& operator[](size_t index) {
        if (index >= size) throw std::out_of_range("Index out of range");
        return data[index];
    }

    size_t get_size() const { return size; }

    // Methods to support range-based for loop
    Iterator begin() { return Iterator(data); }
    Iterator end() { return Iterator(data + size); }
};

// Example usage
int main() {
    CustomVector<int> customVec;
    customVec.push_back(1);
    customVec.push_back(2);
    customVec.push_back(3);

    for (auto& c : customVec) {
        // This loop now works!
        std::cout << c << " ";
    }
    std::cout << std::endl;

    getchar();

    return 0;
}