当当当当！
时间过的真的好快，C语言已经学完了，开始学c++了，博客也没有坚持写，新阶段新开始嘛，希望能按时写奥！
- 命名空间
作用域：不可以在同一个作用域下声明两个相同名字的变量
1 #include <iostream> 2 using namespace std; 3 int age = 300;//注释掉这行 4 namespace Person 5 { 6 int age = 200; 7 } 8 namespace Bird 9 { 10 int age = 100; 11 int sex = 101; 12 } 13 using namespace Bird; 14 int main() 15 { 16 cout<<::age<<endl;//查看这行变化 全局变量优先级高 17 cout<<Person::age<<endl; 18 cout<<Bird::age<<endl; 19 cout<<::sex<<endl; 20 }
- new delete
1 #include <iostream> 2 using namespace std; 3 int main() 4 { 5 int *p = new int; 6 *p = 10; 7 cout<<*p<<endl; 8 delete p; 9 p = 0; 10 11 int *arr = new int[10]; 12 arr[0] = 0; 13 arr[1] = 1; 14 cout<<arr[0]<<" "<<arr[1]<<endl; 15 cout<<arr<<endl; 16 delete[] arr;//delete 数组要加[] 17 //cout<<arr<<endl; 18 //delete之后指针还指向地址，但该空间已经不属于我，不要对它进行操作！ 19 arr = 0; 20 21 int *a = new int(10);//将a指向的int初始化为10 22 cout<<*a<<endl; 23 delete a; 24 a = 0; 25 }
- 缺省函数参数
1 #include <iostream> 2 using namespace std; 3 4 void Show(int a ,int b , int c = 2, int d = 3); 5 int main() 6 { 7 Show(100,200); 8 int arr[10] = {0,1,2,3,4,5,6,7,8,9}; 9 } 10 //不能再函数实现中加参数，如果函数声明中已存在则重复定义，如果没有则格式错误 11 void Show(int a ,int b , int c , int d ) 12 { 13 cout << a << " " << b <<endl; 14 cout << c << " " << d <<endl; 15 }
-
for循环
1 for(auto i : arr)//auto可自动识别arr中类型 2 { 3 cout<< i << " "; 4 }
- 函数重载
函数名相同，函数参数个数或类型不同
- 引用
值传递，地址传递和引用
1 #include <iostream> 2 using namespace std; 3 void Num(int a,int b); 4 void Adress(int *a,int *b); 5 void Yinyong(int &aa, int &bb); 6 int main() 7 { 8 int a = 5; 9 int b = 6; 10 cout<<a<<" "<< b<<endl; 11 Num(a,b); 12 cout<<a<<" "<< b<<endl; 13 Adress(&a,&b); 14 cout<<a<<" "<< b<<endl; 15 Yinyong(a,b); 16 cout<<a<<" "<< b<<endl; 17 18 } 19 void Num(int a,int b) 20 { 21 int c; 22 c = a; 23 a = b; 24 b = c; 25 } 26 void Adress(int *a,int *b) 27 { 28 int c = *a; 29 *a = *b; 30 *b = c; 31 } 32 void Yinyong(int &a, int &b) 33 { 34 int c; 35 c = a; 36 a = b; 37 b = c; 38 }