一、Xmind整理：
关键词总结：
二、上课笔记整理：
1.auto关键字
#include <iostream>
using namespace std;
int fun(int a, int b, float *c, char d, double *e,int f)
{
return 1+2;
}
int main()
{
//定义一个函数指针，指向fun函数
int (*p)(int , int , float *, char , double *,int ) = fun;
//用auto来完成
auto ptr = fun;
return 0;
}
#include <iostream>
using namespace std;
template <typename T>
void fun(T a)
{
auto b = a;
cout << "b的数据类型：" << typeid (b).name() << endl;
}
int main()
{
int a =10;
fun(a);
return 0;
}
2.lambda表达式
#include <iostream>
using namespace std;
int main()
{
int a = 100;
double b = 13.45;
char c = 'x';
cout << "main-&a:" << &a << " a = " << a << endl;
// auto fun = [a,b,c]()mutable{
// auto fun = [=]()mutable{
auto fun = [&a,&b](){
cout << "lambda--&a " << &a << " a = " << a << endl;
a = 200;
cout << "lambda--&a " << &a << " a = " << a << endl;
};
fun();
cout << "main-&a:" << &a << " a = " << a << endl;
return 0;
}
#include <iostream>
using namespace std;
int main()
{
int a = 100;
double b = 13.45;
char c = 'x';
cout << "main-&a:" << &a << " a = " << a << endl;
// auto fun = [a,b,c]()mutable{
// auto fun = [=]()mutable{
auto fun = [&a,&b](string name = "hello world")->string{
cout << "lambda--&a " << &a << " a = " << a << endl;
a = 200;
cout << "lambda--&a " << &a << " a = " << a << endl;
return name;
};
cout << fun("hello kitty") << endl;
cout << "main-&a:" << &a << " a = " << a << endl;
return 0;
}
3.隐式类型转换（自动类型转换）
int num_int = 10;
double num_double = num_int; // 隐式将int转换为double
4.显示类型转换（强制类型转换）
①静态转换
double num_double = 3.14;
int num_int = static_cast<int>(num_double); // 显式将double转换为int
②动态转换
class Base {
virtual void foo() {}
};
class Derived : public Base {};
Base* base_ptr = new Derived;
Derived* derived_ptr = dynamic_cast<Derived*>(base_ptr); // 显式将基类指针转换为派生类指针
③常量转换
const int a =10; //
int *p;
p = &a; // 合不合法？ no
const int num_const = 5;
int* num_ptr = const_cast<int*>(&num_const); // 去除const限定符
④重新解释转换
int num = 42;
float* float_ptr = reinterpret_cast<float*>(&num); // 重新解释转换
5.C风格类型转换
①c样式转换
int num_int = 10;
double num_double = (double)num_int; // C样式强制类型转换
②函数样式转换（函数式转换）
int num_int = 10;
double num_double = double(num_int); // C++函数样式类型转换
6.vector的构造函数
#include <iostream>
#include <vector>
using namespace std;
//算法
void printVector(vector<int> &v)
{
vector<int>::iterator iter; //定义了这样容器类型的迭代器
for(iter = v.begin(); iter != v.end(); iter++)
{
cout << *iter << " ";
}
cout << endl;
}
int main()
{
//容器
vector<int> v; //无参构造函数
v.push_back(10); //尾插
v.push_back(20);
v.push_back(30);
v.push_back(40);
//算法
printVector(v);
vector<int> v2(v.begin(),v.end());
printVector(v2);
vector<int> v3(6,100);
printVector(v3);
vector<int> v4 = v3;
printVector(v4);
vector<int> v5(v2);
printVector(v5);
return 0;
}
7.vector的容量大小
#include <iostream>
#include <vector>
using namespace std;
//算法
void printVector(vector<int> &v)
{
vector<int>::iterator iter; //定义了这样容器类型的迭代器
for(iter = v.begin(); iter != v.end(); iter++)
{
cout << *iter << " ";
}
cout << endl;
}
int main()
{
//容器
vector<int> v; //无参构造函数
v.push_back(10); //尾插
v.push_back(20);
v.push_back(30);
v.push_back(40);
//算法
printVector(v);
vector<int> v2(v.begin(),v.end());
printVector(v2);
vector<int> v3(6,100);
printVector(v3);
vector<int> v4 = v3;
printVector(v4);
vector<int> v5(v2);
printVector(v5);
vector<int> v6;
v6 = v5;
printVector(v6);
v6.assign(v5.begin(),v5.end());
printVector(v6);
v6.assign(8,99);
printVector(v6);
if(v6.empty())
{
cout << "容器为空" << endl;
}
else
{
cout << "容器的容量大小：" << v6.capacity() << endl;
cout << "容器的大小：" << v6.size() << endl;
v6.resize(15);
printVector(v6);
}
return 0;
}
8.vector的元素提取
#include <iostream>
#include <vector>
using namespace std;
//算法
void printVector(vector<int> &v)
{
vector<int>::iterator iter; //定义了这样容器类型的迭代器
for(iter = v.begin(); iter != v.end(); iter++)
{
cout << *iter << " ";
}
cout << endl;
}
int main()
{
//容器
vector<int> v; //无参构造函数
v.push_back(10); //尾插
v.push_back(20);
v.push_back(30);
v.push_back(40);
//算法
printVector(v);
// v.pop_back();//尾删
// printVector(v);
// v.insert(v.begin()+1,99);
// printVector(v);
// v.insert(v.begin(),4,77);
// printVector(v);
// v.erase(v.begin());
// printVector(v);
// v.erase(v.begin(),v.end());
// printVector(v);
v.clear();
printVector(v);
cout << "------------------" <<endl;
vector<int> vv;
for(int i=0;i<5;i++)
{
vv.push_back(i);
}
cout << vv.at(3) << endl;
cout << vv[3] << endl;
cout << vv.front() << endl;
cout << vv.back() << endl;
return 0;
}
9.文件操作
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
//1包含头文件
//2创建流对象
ofstream ofs;
//3打开文件
ofs.open("E:/ready_class/stu.txt",ios::out);
//4写入数据
ofs << "姓名：张三" << endl;
ofs << "年龄：34" << endl;
//5关闭文件
ofs.close();
//1包含头文件
//2创建流对象
ifstream ifs;
//3打开文件
ifs.open("E:/ready_class/stu.txt",ios::in);
//4读取数据
char buff[1024];
while(ifs>>buff)
{
cout << buff << endl;
}
//5.关闭文件
ifs.close();
return 0;
}
