C++关于引用(reference)的代码案例

数据类型 &引用名 = 变量名;

#include <iostream>
using namespace std;
int main() {
    int a = 10;
    int &ref = a;
    cout << "a = " << a << endl; // 输出 a 的值
    cout << "ref = " << ref << endl; // 输出引用 ref 的值
    return 0;
}

#include <iostream>
using namespace std;
void swap(int &a, int &b) {
    int temp = a;
    a = b;
    b = temp;
}
int main() {
    int x = 10, y = 20;
    cout << "x = " << x << ", y = " << y << endl;
    swap(x, y);
    cout << "x = " << x << ", y = " << y << endl;
    return 0;
}

#include <iostream>
using namespace std;
int &max(int &a, int &b) {
    if (a > b) return a;
    else return b;
}
int main() {
    int x = 10, y = 20;
    max(x, y) = 30;
    cout << "x = " << x << ", y = " << y << endl;
    return 0;
}

#include <iostream>
using namespace std;
int main() {
    int a = 10;
    const int &ref1 = a; // 引用指向常量
    int &const ref2 = a; // 常量引用，即引用不能被修改
    const int &const ref3 = a; // 常量引用指向常量，引用和变量都不能被修改
    cout << "ref1 = " << ref1 << endl;
    cout << "ref2 = " << ref2 << endl;
    cout << "ref3 = " << ref3 << endl;
    return 0;
}

#include <iostream>
using namespace std;
void printArray(int (&a)[3][3]) {
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            cout << a[i][j] << " ";
        }
        cout << endl;
    }
}
int main() {
    int a[3][3] = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
    printArray(a);
    return 0;
}

void swap(int &x, int &y) {
    int temp = x;
    x = y;
    y = temp;
}
int main() {
    int a = 1, b = 2;
    swap(a, b);
    return 0;
}

#include<iostream>
using namespace std;
void square(int & x) {
    x *= x;
}
int main() {
    int a = 2;
    square(a);
    cout << "The square of 'a' is: " << a << endl;
    return 0;
}

#include<iostream>
using namespace std;
void print(int & x) {
    cout << "The value of 'x' is: " << x << endl;
}
int main() {
    int a = 5;
    print(a);
    return 0;
}

#include<iostream>
#include<string>
using namespace std;
class Person {
    private:
        string name;
        int age;
    public:
        void setName(string & n) {
            name = n;
        }
        void setAge(int & a) {
            age = a;
        }
        void print() {
            cout << "Name: " << name << ", Age: " << age << endl;
        }
};
int main() {
    string name = "Jack";
    int age = 25;
    Person p1;
    p1.setName(name);
    p1.setAge(age);
    p1.print();
    return 0;
}

#include<iostream>
using namespace std;
const int ROW = 5;
const int COL = 5;
void print_array(int (* arr)[COL]) {
    for(int i=0; i<ROW; i++) {
        for(int j=0; j<COL; j++) {
            cout << arr[i][j] << " ";
        }
        cout << endl;
    }
}
int main() {
    int arr[ROW][COL] = {{1, 1, 1, 1, 1}, {2, 2, 2, 2, 2}, {3, 3, 3, 3, 3}, {4, 4, 4, 4, 4}, {5, 5, 5, 5, 5}};
print_array(arr);
return 0;
}

int main() {
    int &a; // 错误：引用必须在定义时初始化
    return 0;
}

#include<iostream>
using namespace std;
int &get_int() {
    int a = 5;
    return a; // 错误：返回局部变量引用
}
int main() {
    int b = get_int();
    cout << "The value of 'b' is: " << b << endl; // 输出'The value of 'b' is: -858993460'，出现了未定义行为
    return 0;
}

int main() {
    int &a = 5; // 错误：不能将引用绑定到常量字面量
    return 0;
}

int main() {
    int *ptr = NULL;
    int &ref = *ptr; // 错误：引用指向空值，会导致未定义行为。
    return 0;
}

int main() {
    int a = 1, b = 2;
    int &ref = a;
    ref = b; // 引用a被改变，而不是b
    return 0;
}