1、引用

#include<bits/stdc++.h>
using namespace std;

void swap(int &a,int &b){
    int temp = a;
    a = b;
    b = temp;
}
void swap(int *a,int *b){
    int temp = *a;
    *a = *b;
    *b = temp;
}

int main(){
    int a = 1,b = 2;
    swap(a,b);
    cout<<a<<" "<<b<<endl;
    swap(
 
&a,&b);
    cout<<a<<" "<<b<<endl;
} 

#include<bits/stdc++.h>
using namespace std;
int n = 1;
int & set_value(){return n;}
int main(){
    set_value() = 2;
    cout<<n<<endl;
} 

2、const關鍵字

#include<bits/stdc++.h>
using namespace std;

int
 
 main(){
    int a = 1;
    const int & b = a;
    b = 2;
    cout<<a<<endl;
} 

[Error] assignment of read-only reference 'b'

#include<bits/stdc++.h>
using namespace std;

int main(){
    int a = 1;
    const int & b = a;
    a = 2;    
    cout<<a<<endl;
} 

輸出:
 
2

cont int * 不能改變該位置的值，但可以換位置

3、動態記憶體分配

#include<bits/stdc++.h>
using namespace std;

int main(){
    int * p = new int  ;
    *p = 2;
    cout<<*p<<endl;
    delete p;
    cout<<*p<<endl;
} 

2
8526352

#include<bits/stdc++.h>
using namespace std;

int main(){
    int * p = new int [10];
    p[1] = 1;
    cout<<p[1]<<endl;
    delete [] p ;    
} 

1

4、行內函數和數引數預設值

#include<bits/stdc++.h>
using namespace std;
inline int max(int a,int b){
    return a>b?a:b; 
}
inline double max(double a,double b){
    return a>b?a:b; 
}
inline int max(int a,int b,int c){
    return a>b?max(a,c):max(b,c); 
}
inline void g(int a,int b = 1){
    cout<<a<<" "<<b<<endl;
}
int main(){
    cout<<max(1,2)<<" "<<max(1.2,1.3)<<" "<<max(1,2,3)<<endl;
    g(3);
    
} 

2
8526352

5、類和物件的基本概念與用法(1)

面向物件 = 類 + 類 + 類+ 類+ 類+ 類+ 類+ 類......

#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#include<bits/stdc++.h>
using namespace std;
class rectangle{
    public:
        int w,h;
        void init(int _w,int _h){
            w = _w;
            h = _h;
        } 
        void area(){
            cout<<w*h<<endl;
        }
        void perimeter(){
            cout<<(w+h)*2<<endl;
        }
};
int main(){
    rectangle r;
    r.init(1,2);
    r.area();
    r.perimeter();
    rectangle &r2 = r;
    r2.area();
    rectangle *r3 = &r;
    r3->area();
    return 0;
}

2
6
2
2

不加public 預設private