C++类模板与泛型编程

C类模板与泛型编程类模板是C泛型编程的核心允许定义与类型无关的数据结构。模板在编译期实例化为每种类型生成专门的代码。类模板的基本定义使用template语法。#include#include#includetemplateclass Array {T* data_;size_t size_;public:explicit Array(size_t n) : data_(new T[n]()), size_(n) {std::cout Array of n elements\n;}~Array() { delete[] data_; }Array(const Array other) : data_(new T[other.size_]), size_(other.size_) {for (size_t i 0; i size_; i) data_[i] other.data_[i];}Array operator(const Array other) {if (this ! other) {T* new_data new T[other.size_];for (size_t i 0; i other.size_; i) new_data[i] other.data_[i];delete[] data_;data_ new_data;size_ other.size_;}return *this;}T operator[](size_t i) { return data_[i]; }const T operator[](size_t i) const { return data_[i]; }size_t size() const { return size_; }T* begin() { return data_; }T* end() { return data_ size_; }const T* begin() const { return data_; }const T* end() const { return data_ size_; }};void class_template_basic() {Array ints(5);for (size_t i 0; i ints.size(); i) ints[i] i * 10;for (int v : ints) std::cout v ;std::cout \n;Array doubles(3);doubles[0] 1.5;doubles[1] 2.5;doubles[2] 3.5;Array strings(2);strings[0] Hello;strings[1] World;}模板参数可以是类型、非类型或模板模板参数。templateclass FixedArray {T data_[N];public:T operator[](size_t i) { return data_[i]; }const T operator[](size_t i) const { return data_[i]; }constexpr size_t size() const { return N; }T* begin() { return data_; }T* end() { return data_ N; }};void non_type_params() {FixedArray arr;for (size_t i 0; i arr.size(); i) arr[i] i * i;for (int v : arr) std::cout v ;std::cout \n;std::cout Size: arr.size() \n;}模板特化为特定类型提供特殊实现。templateclass TypeProcessor {public:void process(T value) {std::cout Generic: value \n;}};templateclass TypeProcessor {public:void process(int value) {std::cout Specialized for int: value * 2 \n;}};templateclass TypeProcessor {public:void process(const std::string value) {std::cout String length: value.length() \n;}};void template_specialization() {TypeProcessor dp;dp.process(3.14);TypeProcessor ip;ip.process(42);TypeProcessor sp;sp.process(Hello);}类模板偏特化。templateclass Resource {public:void use() {std::cout Generic resource\n;}};templateclass Resource {T* ptr_;public:explicit Resource(T* p) : ptr_(p) {}~Resource() { delete ptr_; }T* operator-() { return ptr_; }T operator*() { return *ptr_; }void use() {std::cout Managed resource\n;}};templateclass Resource {T* ptr_;public:explicit Resource(T* p) : ptr_(p) {}T* operator-() { return ptr_; }T operator*() { return *ptr_; }};继承类模板。templateclass Base {protected:T value_;public:explicit Base(T v) : value_(v) {}virtual void show() { std::cout value_ \n; }};templateclass Derived : public Base {U extra_;public:Derived(T v, U e) : Base(v), extra_(e) {}void show() override {std::cout this-value_ , extra_ \n;}};void template_inheritance() {Derived d(42, answer);d.show();}模板成员函数。class Utils {public:templatestatic T max(T a, T b) {return a b ? a : b;}templatestatic T min(T a, T b) {return a b ? a : b;}};void template_members() {std::cout Max(3, 7): Utils::max(3, 7) \n;std::cout Min(3.14, 2.71): Utils::min(3.14, 2.71) \n;}类模板是STL的基础STL中的容器、迭代器和算法都是类模板的应用。