c++ 引用

#include <iostream>
using namespace std;
void method2(int& param) {
    param = param + 1;
    cout << "method2 inner:" << param << endl;  //method2 inner:2
}
void method1(int param) {
    param = param + 1;
    cout << "method1 inner:" << param << endl;  //method1 inner:2
}
int main() {
    int a { 1 };
    method1(a);
    cout << "main:" << a << endl;  //main:1
    method2(a);
    cout << "main:" << a << endl;  //main:2
    char c = getchar();
    return 0;
}