C概念约束编程概念Concepts是C20引入的特性用于对模板参数施加约束。概念提供了比SFINAE更清晰的语法和更好的错误信息。概念使用concept关键字定义类型约束。#include#include#includetemplateconcept Integral std::is_integral_v;templateconcept FloatingPoint std::is_floating_point_v;templateT double_value(T value) {std::cout Doubling integer\n;return value * 2;}templateT double_value(T value) {std::cout Doubling float\n;return value * 2;}void concept_basic() {std::cout double_value(42) \n;std::cout double_value(3.14) \n;}requires子句指定模板约束。templaterequires std::is_arithmetic_vT add(T a, T b) {return a b;}templateT multiply(T a, T b) requires std::is_arithmetic_v {return a * b;}void requires_clause() {std::cout Add: add(10, 20) \n;std::cout Multiply: multiply(3.0, 4.0) \n;}自定义概念可以组合多个约束。templateconcept Numeric std::is_arithmetic_v !std::is_same_v;templateconcept Addable requires(T a, T b) {{ a b } - std::convertible_to;};templateT compute(T value) {return value * value;}void custom_concepts() {std::cout compute(5) \n;std::cout compute(3.14) \n;}requires表达式检查类型是否满足特定操作。templateconcept HasSize requires(T t) {{ t.size() } - std::convertible_to;};templatesize_t get_size(const T container) {return container.size();}void requires_expression() {std::vector vec {1, 2, 3};std::cout Size: get_size(vec) \n;}概念可以用于约束类模板。templateconcept Comparable requires(T a, T b) {{ a b } - std::convertible_to;{ a b } - std::convertible_to;};templateclass SortedContainer {std::vector data_;public:void insert(const T value) {auto it std::lower_bound(data_.begin(), data_.end(), value);data_.insert(it, value);}void display() const {for (const auto val : data_) {std::cout val ;}std::cout \n;}};概念提供了更清晰的模板错误信息。templateconcept Printable requires(T t) {{ std::cout t };};templatevoid print(const T value) {std::cout value \n;}概念是现代C模板编程的重要特性提供了更好的类型安全和可读性。
