C++const正确性实践

Cconst正确性实践const正确性是C编程的重要原则通过const关键字明确表达不可变性提高代码的安全性和可读性。const成员函数承诺不修改对象状态可以被const对象调用。#include#include#includeclass Point {int x_, y_;public:Point(int x, int y) : x_(x), y_(y) {}int x() const { return x_; }int y() const { return y_; }void set_x(int x) { x_ x; }void set_y(int y) { y_ y; }double distance_from_origin() const {return std::sqrt(x_ * x_ y_ * y_);}void display() const {std::cout ( x_ , y_ )\n;}};void const_member_function() {const Point p1(3, 4);std::cout x: p1.x() , y: p1.y() \n;std::cout Distance: p1.distance_from_origin() \n;p1.display();}const引用参数避免拷贝并保证不修改参数。void print_vector(const std::vector vec) {for (int val : vec) {std::cout val ;}std::cout \n;}int sum_vector(const std::vector vec) {int total 0;for (int val : vec) {total val;}return total;}void const_reference_params() {std::vector numbers {1, 2, 3, 4, 5};print_vector(numbers);std::cout Sum: sum_vector(numbers) \n;}const返回值防止对临时对象的修改。class String {char* data_;public:explicit String(const char* str) {data_ new char[strlen(str) 1];strcpy(data_, str);}~String() {delete[] data_;}const char* c_str() const {return data_;}String(const String) delete;String operator(const String) delete;};void const_return_value() {String s(Hello);const char* str s.c_str();std::cout String: str \n;}mutable关键字允许const成员函数修改特定成员。class Cache {mutable int access_count_;mutable bool cached_;mutable int cached_value_;int expensive_computation() const {std::cout Computing...\n;return 42;}public:Cache() : access_count_(0), cached_(false), cached_value_(0) {}int get_value() const {access_count_;if (!cached_) {cached_value_ expensive_computation();cached_ true;}return cached_value_;}int access_count() const {return access_count_;}};void mutable_example() {const Cache cache;std::cout Value: cache.get_value() \n;std::cout Value: cache.get_value() \n;std::cout Access count: cache.access_count() \n;}const迭代器和const_iterator有不同的含义。void const_iterators() {std::vector vec {1, 2, 3, 4, 5};for (std::vector::const_iterator it vec.begin(); it ! vec.end(); it) {std::cout *it ;}std::cout \n;const std::vector const_vec {10, 20, 30};for (auto it const_vec.begin(); it ! const_vec.end(); it) {std::cout *it ;}std::cout \n;}const指针和指向const的指针是不同的概念。void const_pointers() {int x 10;int y 20;const int* ptr1 x;std::cout ptr1: *ptr1 \n;ptr1 y;int* const ptr2 x;*ptr2 30;std::cout x after ptr2: x \n;const int* const ptr3 x;std::cout ptr3: *ptr3 \n;}const正确性在类设计中确保接口的清晰性。class Rectangle {int width_, height_;public:Rectangle(int w, int h) : width_(w), height_(h) {}int width() const { return width_; }int height() const { return height_; }int area() const {return width_ * height_;}void set_width(int w) {width_ w;}void set_height(int h) {height_ h;}void scale(double factor) {width_ static_cast(width_ * factor);height_ static_cast(height_ * factor);}};void const_interface_design() {const Rectangle rect(10, 20);std::cout Area: rect.area() \n;Rectangle mutable_rect(5, 10);mutable_rect.scale(2.0);std::cout Scaled area: mutable_rect.area() \n;}const正确性是编写高质量C代码的重要实践它使代码的意图更加明确减少错误。