C++教程(超长最全入门)

//单行注释

//x64处理器 64位window10 vs2015 
#include <iOStream>
using namespace std;
int main()
{
	bool b;
	char c;short s; int i; long l; long long ll; float f; double d; long double ld;long float lf;
	unsigned char uc; unsigned short us; unsigned int ui; unsigned long ul; unsigned long long ull;
	cout << sizeof(bool) <<  endl;
	cout << sizeof(char)<<" " << sizeof(short)<<" "<< sizeof(signed int) << " " << sizeof(long) << " " << sizeof(signed long long) << " " << sizeof(float) << " " << sizeof(double) << " " << sizeof(long float) << " " << sizeof(long double) << endl;
	cout <<sizeof(unsigned char)<<" "<< sizeof(unsigned short) << " " << sizeof(unsigned int) << " " << sizeof(unsigned long) << " " << sizeof(unsigned long long) << endl;
	cout << sizeof(unsigned) << endl;
	cout << "hello World!!!" <<endl;
	system("pause");
	return 0;
}

//使用typedef为一个已有的类型取一个新的名字,语法如下：
typedef type newname
//eg：
typedef int feet
feet distance

//枚举类型的语法:
enum 枚举名{
	标识符[=整型常数], 
     标识符[=整型常数], 
... 
    标识符[=整型常数]
}枚举变量;

enum course {math,chinese,english,physics,chemistry}c;
c = english;
cout<<c<<endl;  //2
//english为1 physics为2 chemistry为3，chinese仍为1，math仍为0
enum course {math,chinese,english=1,physics,chemistry};

int x = y = z = 66;//错误
int x = 3,y = 3,z = 3;
int x, y ,z = 3;
x = y = z;

// 变量声明
extern int a, b;
int main ()
{
  // 变量定义
  int a, b;
  // 初始化
  a = 23;
  b = 25;
  return 0;
}

int i = 66;
int main ()
{
  int i = 88;
  cout << i<<endl;//8
  return 0;
}
float f;
double d;
char c;
int *p;
int main()
{
	cout << i << f << d << c << p << endl;//000 00000000
	return 0
}

sizeof            //返回变量的大小，eg:sizeof(a)返回4 a是整型  sizeof(int)
Condition?X:Y     //三元运算符 Condition为true，值为X，否则值为Y
,                //逗号表达式，值为最后一个表达式的值
.和->            //用于引用类、结构和公用体的成员
Cast            //强制类型转换符  eg:int(2.202)返回2
&              //指针运算符 返回变量的地址
*             //指针运算符  指向一个变量

while(conditon)//0为false,非0为true
{
	statement(s);
}

for(init;conditon;increment)//0为false,非0或什么也不写为true
{
	statement(s);
}

int array[5] = { 11, 22, 33, 44, 55 };
for (int x : array)
{
	cout << x << " ";
}
cout << endl;
// auto 类型也是 C++11 新标准中的，用来自动获取变量的类型
for (auto x : array)
{
	cout << x << " ";
}

int a[4] = { 4,3,2,1 };
for each (int var in a)
{
	cout << var << " ";
}

if(expr)
{
	statement;//如果expr为true将执行的语句块 
}
if(expr)
{
   statement1;// 如果expr为true将执行的语句块
}
else
{
   statement2;// 如果expr为false将执行的语句
}
if(expr1)
{
   statement1;// 如果expr1为true将执行的语句块
}
elseif(expr2)
{
   statement2;// 如果expr2为true将执行的语句块
}
...
else
{
	statementElse;// 当上面的表达式都为false执行的语句块
}

switch(expression){
    case constant-expression  :
       statement(s);
       break; 
    case constant-expression  :
       statement(s);
       break; 
    // 您可以有任意数量的 case 语句
    default : // 可选的
       statement(s);
}

char c = 'A';
	switch (c)
	{
	case 'A':
	case 'B':
	case 'C':
		cout << "及格了" << endl;
		break;
	default:
		cout << "不及格" << endl;
	}

//如果 Exp1 为真，则计算 Exp2 的值，结果即为整个 ? 表达式的值。如果 Exp1 为假，则计算 Exp3 的值，结果即为整个 ? 表达式的值
Exp1 ? Exp2 : Exp3;

//如果标识符被#define定义过，执行程序段1，否则执行程序段2
#ifdef 标识符
	程序段1
#else
	程序段2
#endif
//如果标识符没有被#define定义过，执行程序段1，否则执行程序段2
#ifndef 标识符
	程序段1
#else
	程序段2
#endif
//如果表达式为true，执行程序段1，否则执行程序段2
#if 表达式
	程序段1
#else
	程序段2
#endif

int arr1[4] = {1,2,3,4};
int arr2[4] = { 1,2 };
int arr[4] = {0];//所有元素为0
static int arr3[3];
int arr4[4];
cout << "arr1:"<<arr1[0] << arr1[1] << arr1[2] << arr1[3] << endl;
cout << "arr2:" << arr2[0] << arr2[1] << arr2[2] << arr2[3] << endl;
cout << "arr3:" << arr3[0] << arr3[1] << arr3[2] << arr3[3] << endl;
cout << "arr4:" << arr4[0] << arr4[1] << arr4[2] << arr4[3] << endl;

int arr1[2][3];
int arr[2][3] = {0];//所有元素为0
int arr2[2][3] = { {1,2,3},{4,5,6} };
int arr3[2][3] = { 1,2,3 ,4,5,6 };
int arr4[2][3] = { {1},{4,6} };
int arr5[][3] = { 1,2,3 ,4,5,6 };

//字符串长度为8个字节,最后一位是'\0'。
char array[10] = "yuanrui";//yuanrui\0\0\0
//也可以不用定义字符串长度，如：
char arr[] = "yuanrui";//yuanrui\0

double *p;
double arr[10];
p = arr;//p = &arr[0];
*(p+3);//arr[3]

int* arr1 = new int[2];//delete []arr1;
int* arr2 = new int[3]{ 1,2 };//delete []arr2

int m=2, n=3;
int** arr3 = new int*[2];//delete []arr3
for (int i = 0; i < 10; ++i)
{ 
	arr3[i] = new int[3]; // delete []arr3[i]
}
int* arr4 = new int[m*n];//数据按行存储 delete []arr3

int * function();
int** function();

int a[3];
//第一种方法
cout<<sizeof(a)/sizeof(a[0])<<endl;
//第二种方法
cout << end(a) - begin(a) << endl;
//二维数组
int arr[5][3];
int lines = sizeof(arr) / sizeof(arr[0][0]);
int row = sizeof(arr) / sizeof(arr[0]);//行
int col = lines / row;//列
cout << row << "::"<<col << endl;
cout << end(arr) - begin(arr) << endl;//5行

函数类型 函数名(参数列表);
eg:
int max(int a,int b);//声明函数时，a,b可以省略
int max(int,int);
void show();

函数类型 函数名(参数列表)
{
	函数体;
}
eg:
int max(int a,int b)
{
	int z;
	z = a>b?a:b;
	return z;
}

//传值-修改函数内的形式参数对实际参数没有影响
int add(int value)
{
	value++;
	return value;
}
int main()
{
	int v = 10;
	cout << "add() = " << add(v) << endl;//add() = 11
		cout << "v = " << v << endl;//v = 10
	return 0;
}
//指针-修改形式参数会影响实际参数
int add(int* pValue)
{
	(*pValue)++;
	return *pValue;
}
int main()
{
	int v = 10;
	cout << "add() = " << add(&v) << endl;//add() = 11
	cout << "v = " << v << endl;//v = 11
	return 0;
}
//引用-修改形式参数会影响实际参数
int add(int &value)
{
	value++;
	return value;
}
int main()
{
	int v = 10;
	cout << "add() = " << add(v) << endl;//add() = 11
	cout << "v = " << v << endl;//v = 11
	return 0;
}

int sum(int a, int b=2)
{
  return (a + b);
}
int main ()
{
   cout << "Total value is :" << sum(100, 200);<< endl;//Total value is :300
   cout << "Total value is :" << sum(100);<< endl;//Total value is :102
   return 0;
}

函数名(实参列表);
show();

int a()
{
	return 666;
}
int b(int sum)
{
	return sum+a()
}
int main()
{
	cout<<b(222)<<endl;//888
	return 0;
}

//直接递归调用：求1+...n的值
int total(int sum)
{
	if (sum == 1)
	{
		return 1;
	}
	return sum + total(sum - 1);
}
int main()
{
	cout << "total = " << total(10) << endl;//total = 55
	system("pause");
	return 0;
}
//间接递归调用
int f2();
int f1()
{
...
  f2()
}
int f2()
{
	f1();
}

int add(int a,int b)
{
	return a+b;
}
double add(double a,double b)
{
	return a+b;
}
int add(int a,int b,int c)
{
	return a+b+c;
}

inline 函数类型 函数名(形参列表)
{
	函数体;
}
inline int add(int a, int b)
{
	return a + b;
}

#include <iostream>
#include <string>
using namespace std;
inline int add(int a, int b)
{
	return a + b;//断点1
}
int main()
{
	int result = add(12, 34);
	cout << result << endl;//断点2
	return 0;
}

...
		int result = add(12, 34);
00B620DE  mov         eax,0Ch  
00B620E3  add         eax,22h  //对eax中和22h中值进行相加，赋值给eax
00B620E6  mov         dWord ptr [result],eax  
		cout << result << endl;
00B620E9  mov         esi,esp  
00B620EB  push        offset std::endl<char,std::char_traits<char> > (0B610A5h)  
00B620F0  mov         edi,esp  
00B620F2  mov         eax,dword ptr [result]  
00B620F5  push        eax  
00B620F6  mov         ecx,dword ptr [_imp_?cout@std@@3V?$basic_ostream@DU?$char_traits@D@std@@@1@A (0B6D098h)]  
00B620FC  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (0B6D0A8h)]  
00B62102  cmp         edi,esp  
00B62104  call        __RTC_CheckEsp (0B611C7h)  
00B62109  mov         ecx,eax  
00B6210B  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (0B6D0ACh)]  
00B62111  cmp         esi,esp  
00B62113  call        __RTC_CheckEsp (0B611C7h)   
		return 0;

int result = add(12, 34);
00291A4E  push        22h  
00291A50  push        0Ch  
00291A52  call        add (02914D8h)  //调用add函数
00291A57  add         esp,8//移动堆栈指针esp,继续执行主函数
00291A5A  mov         dword ptr [result],eax  
		cout << result << endl;
00291A5D  mov         esi,esp  
00291A5F  push        offset std::endl<char,std::char_traits<char> > (02910A5h)  
00291A64  mov         edi,esp  
00291A66  mov         eax,dword ptr [result]  
00291A69  push        eax  
00291A6A  mov         ecx,dword ptr [_imp_?cout@std@@3V?$basic_ostream@DU?$char_traits@D@std@@@1@A (029D098h)]  
		cout << result << endl;
00291A70  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (029D0A8h)]  
00291A76  cmp         edi,esp  
00291A78  call        __RTC_CheckEsp (02911C7h)  
00291A7D  mov         ecx,eax  
00291A7F  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (029D0ACh)]  
00291A85  cmp         esi,esp  
00291A87  call        __RTC_CheckEsp (02911C7h)  
		system("pause");
00291A8C  mov         esi,esp  
00291A8E  push        offset string "pause" (0299B30h)  
00291A93  call        dword ptr [__imp__system (029D1DCh)]  
00291A99  add         esp,4  
00291A9C  cmp         esi,esp  
00291A9E  call        __RTC_CheckEsp (02911C7h)  
		return 0;

inline int add(int a, int b)
{
	int sum = 0;
	for (int i = 0; i < 100; i++)
		a++;
	for (int i = 0; i < 100; i++)
	{
		for (int i = 0; i < 100; i++)
		{
			sum++;
		}
	}
	return a + b;
}
int main()
{
	int result = add(12, 34);
	cout << result << endl;
	return 0;
}

int result = add(12, 34);
00181A4E  push        22h  
00181A50  push        0Ch  
00181A52  call        add (01814ECh)  ///
00181A57  add         esp,8  
00181A5A  mov         dword ptr [result],eax  
	cout << result << endl;
00181A5D  mov         esi,esp  
00181A5F  push        offset std::endl<char,std::char_traits<char> > (01810A5h)  
00181A64  mov         edi,esp  
00181A66  mov         eax,dword ptr [result]  
00181A69  push        eax  
00181A6A  mov         ecx,dword ptr [_imp_?cout@std@@3V?$basic_ostream@DU?$char_traits@D@std@@@1@A (018D098h)]  
	cout << result << endl;
00181A70  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (018D0A8h)]  
00181A76  cmp         edi,esp  
00181A78  call        __RTC_CheckEsp (01811C7h)  
00181A7D  mov         ecx,eax  
00181A7F  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (018D0ACh)]  
00181A85  cmp         esi,esp  
00181A87  call        __RTC_CheckEsp (01811C7h)  
	return 0;
00181AA3  xor         eax,eax  

char a[5]
//字符个数不够，补0; 字符个数超过报错
char str[7] = {'h','e','i','r','e','n'};
char str[] = {'h','e','i','r','e','n'};
cin>>str;//输入 输入字符串长度一定小于已定义的字符数组长度
cout<<str;//输出

strcat(char s1[],const char s2[]);//将s2接到s1上
strcpy(char s1[],const char s2[]);//将s2复制到s1上
strcmp(const char s1[],const char s2[]);//比较s1,s2 s1>s2返回1 相等返回1，否则返回-1
strlen(char s[]);//计算字符串s的长度 字符串s的实际长度，不包括\0在内

//定义
string 变量;
string str1;
//赋值
string str2 = "ShangHai";
string str3 = str2;
str3[3] = '2';//对某个字符赋值
//字符串数组
string 数组名[常量表达式]
string arr[3];

#include <iostream>
#include <algorithm>
#include <string>
string str;//生成空字符串
string s(str);//生成字符串为str的复制品
string s(str, strbegin,strlen);//将字符串str中从下标strbegin开始、长度为strlen的部分作为字符串初值
string s(cstr, char_len);//以C_string类型cstr的前char_len个字符串作为字符串s的初值
string s(num ,c);//生成num个c字符的字符串
string s(str, stridx);//将字符串str中从下标stridx开始到字符串结束的位置作为字符串初值
size()和length();//返回string对象的字符个数
max_size();//返回string对象最多包含的字符数，超出会抛出length_error异常
capacity();//重新分配内存之前，string对象能包含的最大字符数
>,>=,<,<=,==,!=//支持string与C-string的比较(如 str<”hello”)。  使用>,>=,<,<=这些操作符的时候是根据“当前字符特性”将字符按字典顺序进行逐一得 比较，string (“aaaa”) <string(aaaaa)。    
compare();//支持多参数处理，支持用索引值和长度定位子串来进行比较。返回一个整数来表示比较结果，返回值意义如下：0：相等 1：大于 -1：
push_back() 
insert( size_type index, size_type count, CharT ch );//在index位置插入count个字符ch
insert( size_type index, const CharT* s );//index位置插入一个常量字符串
insert( size_type index, const CharT* s, size_type n);//index位置插入常量字符串
insert( size_type index, const basic_string& str );//index位置插入常量string中的n个字符
insert( size_type index, const basic_string& str, size_type index_str, size_type n);//index位置插入常量str的从index_str开始的n个字符
insert( size_type index, const basic_string& str,size_type index_str, size_type count = npos);//index位置插入常量str从index_str开始的count个字符，count可以表示的最大值为npos.这个函数不构成重载 npos表示一个常数，表示size_t的最大值，string的find函数如果未找到指定字符，返回的就是一个npos
iterator insert( iterator pos, CharT ch );
iterator insert( const_iterator pos, CharT ch );
void insert( iterator pos, size_type n, CharT ch );//迭代器指向的pos位置插入n个字符ch
iterator insert( const_iterator pos, size_type count, CharT ch );//迭代器指向的pos位置插入count个字符ch
void insert( iterator pos, InputIt first, InputIt last );
iterator insert( const_iterator pos, InputIt first, InputIt last );
append() 和 + 操作符
//访问string每个字符串
string s1("yuanrui"); // 调用一次构造函数
// 方法一： 下标法
for( int i = 0; i < s1.size() ; i++ )
     cout<<s1[i];
// 方法二：正向迭代器
for( string::iterator iter = s1.begin();; iter < s1.end() ; iter++)
     cout<<*iter;
 // 方法三：反向迭代器
for(string::reverse_iterator riter = s1.rbegin(); ; riter < s1.rend() ; riter++)
     cout<<*riter;
 iterator erase(iterator p);//删除字符串中p所指的字符
iterator erase(iterator first, iterator last);//删除字符串中迭代器区间[first,last)上所有字符
string& erase(size_t pos = 0, size_t len = npos);//删除字符串中从索引位置pos开始的len个字符
void clear();//删除字符串中所有字符
string& replace(size_t pos, size_t n, const char *s);//将当前字符串从pos索引开始的n个字符，替换成字符串s
string& replace(size_t pos, size_t n, size_t n1, char c); //将当前字符串从pos索引开始的n个字符，替换成n1个字符c
string& replace(iterator i1, iterator i2, const char* s);//将当前字符串[i1,i2)区间中的字符串替换为字符串s
//tolower()和toupper()函数 或者 STL中的transfORM算法
string s = "ABCDEFG";
for( int i = 0; i < s.size(); i++ )
     s[i] = tolower(s[i]);
transform(s.begin(),s.end(),s.begin(),::tolower);
size_t find (constchar* s, size_t pos = 0) const;//在当前字符串的pos索引位置开始，查找子串s，返回找到的位置索引，-1表示查找不到子串
size_t find (charc, size_t pos = 0) const;//在当前字符串的pos索引位置开始，查找字符c，返回找到的位置索引，-1表示查找不到字符
size_t rfind (constchar* s, size_t pos = npos) const;//在当前字符串的pos索引位置开始，反向查找子串s，返回找到的位置索引，-1表示查找不到子串
size_t rfind (charc, size_t pos = npos) const;//在当前字符串的pos索引位置开始，反向查找字符c，返回找到的位置索引，-1表示查找不到字符
size_tfind_first_of (const char* s, size_t pos = 0) const;//在当前字符串的pos索引位置开始，查找子串s的字符，返回找到的位置索引，-1表示查找不到字符
size_tfind_first_not_of (const char* s, size_t pos = 0) const;//在当前字符串的pos索引位置开始，查找第一个不位于子串s的字符，返回找到的位置索引，-1表示查找不到字符
size_t find_last_of(const char* s, size_t pos = npos) const;//在当前字符串的pos索引位置开始，查找最后一个位于子串s的字符，返回找到的位置索引，-1表示查找不到字符
size_tfind_last_not_of (const char* s, size_t pos = npos) const;//在当前字符串的pos索引位置开始，查找最后一个不位于子串s的字符，返回找到的位置索引，-1表示查找不到子串
sort(s.begin(),s.end());
substr(pos,n);//返回字符串从下标pos开始n个字符
strtok()
char str[] = "I,am,a,student; hello world!";
const char *split = ",; !";
char *p2 = strtok(str,split);
while( p2 != NULL )
{
    cout<<p2<<endl;
    p2 = strtok(NULL,split);
}

数据类型 *指针变量名;
int    *ip;    //整型的指针 
double *dp;    //double 型的指针 
float  *fp;    //浮点型的指针 
char   *ch;    //字符型的指针 

数据类型 *指针变量名 = &变量名;
*指针变量名 = &变量名;
int a;
int *p = &a;
int *p2;
p2 = &a;

int x = 3;
int y;
int *p;
p = &x;
y = *p;//y = a

int arr[10],len;
int *p1 = &arr[2],*p2 = &arr[5];
 len = p2-p1;//arr[2] 和arr[5]之间的元素个数 3

指针变量 = new 数据类型(初值);
delete 指针变量;
delete[] 指针变量;//释放为多个变量分配的地址
int *ip;
ip= new int(1);
delete ip;
int *ip;
 ip= new int[10];
 for (int i = 0; i < 10;i++)
 {
	 ip[i] = i;
 }
 delete[] ip;
int a[3][4] = {0};

int arr[10];
int *p1 = arr;// *p1 = &arr[0];
int a[3][5] = { 0 };
int(*ap)[5];
ap = a;
ap+1;//表示下一个一维数组

int a;
int &b = a;//a和b表示相同的变量，具有相同的地址。

void swap(int &r1, int &r2) {
    int temp = r1;
    r1 = r2;
    r2 = temp;
}
int &add1(int &r) {
	r += 1;
	return r;
}
int main()
{
	int a = 12;
	int b = add1(a);
	cout << a << "   "<<b << endl;//13  13
	return 0;
}

int &add1(int &r) {
	r += 1;
	int res = r;
	return res;
}
void test()
{
	int xx = 123;
	int yy = 66;
}
int main()
{
	int a = 12;
	int &b = add1(a);
	int &c = add1(a);
	test();//函数调用，覆盖之前函数的局部数据
	cout << a << "   "<<b <<" "<< c<<endl;//14   -858993460 -858993460
	return 0;
}

struct 结构体类型名
{
	成员类型1 成员名1;
	成员类型2 成员名2;
	... ...
	成员类型n 成员名n;
};

//定义结构体同时声明结构体变量名
struct 结构体类型名
{
	成员类型1 成员名1;
	成员类型2 成员名2;
	... ...
	成员类型n 成员名n;
}变量名1,变量名2,...变量名n;
//先定义结构体
[struct] 结构体类型名 变量名;
//直接定义
struct 
{
	成员类型1 成员名1;
	成员类型2 成员名2;
	... ...
	成员类型n 成员名n;
}变量名1,变量名2,...变量名n;
struct  person
{
	int year;
	int age;
	string name;
}p1 = {2019,24,"heiren"}, p1 = { 2020,24,"heiren" };
struct  person
{
	int year;
	int age;
	string name;
};
struct person p1 = { 2019,24,"heiren" }, p1 = { 2020,24,"heiren" };
struct 
{
	int year;
	int age;
	string name;
}p1 = {2019,24,"heiren"}, p1 = { 2020,24,"heiren" };

struct person
{
	int year;
	int age;
	string name;
}p[2] ={ {2019,24,"heiren"}, { 2020,24,"heiren" }};//可以不指定数组元素个数
p[1].age;

//指定对齐值=8
struct st 
{
	// 空结构体大小1
	char c1;//1
	char c2;//2
	int i1;//8  int  起始地址按照字节对齐的原理应该是它长度4的整数倍
	char c3;//12
	short s4;//12 short 起始地址按照字节对齐的原理应该是它长度2的整数倍 12 + 2 = 12
	double d;//24 double 起始地址按照字节对齐的原理应该是它长度8的整数倍 12->16 + 8 = 24
	char c4;//32   24 + 4 = 28 结构体的总大小为8的整数倍 28->32
	int i2;//32  28+4 = 32
	int i3;//40   
	short s5;//40
};
cout << sizeof(st) << endl;//40
//指定对齐值=4
#pragma  pack(4)
struct st
{
	//1 空结构体大小1
	char c1;//1
	char c2;//2
	int i1;//8
	char c3;//12
	short s4;//12
	double d;//20
	char c4;//24
	int i2;//28
	int i3;//32
	short s5;//36
}s;
cout << sizeof(st) << endl;//36

union 共同体类型名
{
    成员类型1 成员名1;
	成员类型2 成员名2;
	... ...
	成员类型n 成员名n;
};

union data
{
	int i;
	float f;
	char c;
}x = {123};
union data
{
	float f;
	int i;
	char c;
};
data x = {12.3};
union 
{
	char c;
	int i;
	float f;
}x = {'y‘};

共同体变量名.成员名;
union data
{
	int i;
	float f;
	char c;
}x = {12};
int main()
{
	cout << x.i << " " << x.f << " " << x.c << endl;//12 1.68156e-44 
	x.c = 'c';
	cout << x.i <<" "<< x.f << " " << x.c << endl;//99 1.38729e-43 c
	return 0;
}

typedef char *CP;
typedef int INTEGER;

class 类名
{
	public:
		公有数据成员;
		公有成员函数;
	private:
		私有数据成员;
		私有成员函数;
	protected:
		保护数据成员;
		保护成员函数;
};

//类外
返回类型 类名:成员函数名(参数列表)
{
	函数体;
}
//内联函数：类外
inline 返回类型 类名:成员函数名(参数列表)
{
	函数体;
}

//1.声明类同时定义对象
class 类名
{
	类体;
}对象名列表;
//2.先声明类，再定义对象
类名 对象名(参数列表);//参数列表为空时，()可以不写
//3. 不出现类名，直接定义对象
class 
{
	类体;
}对象名列表;
//4.在堆上创建对象
Person p(123, "yar");//在栈上创建对象
Person *pp = new Person(234,"yar");//在堆上创建对象

//1.类中定义 2.类中声明，类外定义
[类名::]构造函数名(参数列表)
{
	函数体
}

class Person
{
public:
	Person(int = 0,string = "张三");
	void show();
private:
	int age;
	string name;
};
Person::Person(int a, string s)
{
	cout<<a<<" "<<s<<endl;
	age = a;
	name = s;
}
void Person::show()
{
	cout << "age="<<age << endl;
	cout << "name=" <<name << endl;
}
int main()
{
     Person p; //0 张三
	Person p2(12);//12 张三
	Person p3(123, "yar");//123 yar
	return 0;
}

类名::构造函数名(参数列表):参数初始化表
{
	函数体;
}
参数初始化列表的一般形式：
参数名1(初值1),参数名2(初值2),...,参数名n(初值n)
class Person
{
public:
	Person(int = 0,string = "张三");
	void show();
private:
	int age;
	string name;
};
Person::Person(int a, string s):age(a),name(s)
{
	cout << a << " " << s << endl;
}

class Person
{
public:
	Person();
	Person(int = 0,string = "张三");
	Person(double,string);
	void show();
private:
	int age;
	double height;
	string name;
};
...

类名::类名(类名&对象名)
{
	函数体;
}
class Person
{
public:
	Person(Person &p);//声明拷贝构造函数
	Person(int = 0,string = "张三");
	void show();
private:
	int age;
	string name;
};
Person::Person(Person &p)//定义拷贝构造函数
{
	cout << "拷贝构造函数" << endl;
	age = 0;
	name = "ABC";
}
Person::Person(int a, string s):age(a),name(s)
{
	cout << a << " " << s << endl;
}
int main()
{
	Person p(123, "yar");
	Person p2(p);
	p2.show();
	return 0;
}
//输出
123 yar
拷贝构造函数
age=0
name=ABC

//1.类中定义 2.类中声明，类外定义
[类名::]~析构函数名()
{
	函数体;
}

类名 *对象指针名;
对象指针 = &对象名;
//访问对象成员
对象指针->数据成员名
对象指针->成员函数名(参数列表)
Person p(123, "yar");
Person* pp = &p;
Person* pp2 = new Person(234,"yar")
pp->show();

数据成员类型 *指针变量名 = &对象名.数据成员名;
函数类型 (类名::*指针变量名)(参数列表);
指针变量名=&类名::成员函数名;
(对象名.*指针变量名)(参数列表);
Person p(123, "yar");
void(Person::*pfun)();
pfun = &Person::show;
(p.*pfun)();

class Person
{
public:
	Person(int = 0,string = "张三");
	void show();
private:
	int age;
	string name;
};
Person::Person(int a, string s):age(a),name(s)
{
	cout << a << " " << s << endl;
}
void Person::show()
{
	cout << "age="<<this->age << endl;
	cout << "name=" <<this->name << endl;
}

//类内声明，类外定义
class xxx
{
	static 数据类型 静态数据成员名;
}
数据类型 类名::静态数据成员名=初值
//访问
类名::静态数据成员名;
对象名.静态数据成员名;
对象指针名->静态数据成员名;

//类内声明，类外定义
class xxx
{
	static 返回值类型 静态成员函数名(参数列表);
}
返回值类型 类名::静态成员函数名(参数列表)
{
	函数体;
}
//访问
类名::静态成员函数名(参数列表);
对象名.静态成员函数名(参数列表);
对象指针名->静态成员函数名(参数列表);

//1.将非成员函数声明为友元函数
class Person
{
public:
	Person(int = 0,string = "张三");
	friend void show(Person *pper);//将show声明为友元函数
private:
	int age;
	string name;
};
Person::Person(int a, string s):age(a),name(s)
{
	cout << a << " " << s << endl;
}
void show(Person *pper)
{
	cout << "age="<< pper->age << endl;
	cout << "name=" << pper->name << endl;
}
int main()
{;
	Person *pp = new Person(234,"yar");
	show(pp);
	system("pause");
	return 0;
}
//2.将其他类的成员函数声明为友元函数
//person中的成员函数可以访问MobilePhone中的私有成员变量
class MobilePhone;//提前声明
//声明Person类
class Person
{
public:
	Person(int = 0,string = "张三");
	void show(MobilePhone *mp);
private:
	int age;
	string name;
};
//声明MobilePhone类
class MobilePhone
{
public:
	MobilePhone();
	friend void Person::show(MobilePhone *mp);
private:
	int year;
	int memory;
	string name;
};
MobilePhone::MobilePhone()
{
	year = 1;
	memory = 4;
	name = "iphone 6s";
}
Person::Person(int a, string s):age(a),name(s)
{
	cout << a << " " << s << endl;
}
void Person::show(MobilePhone *mp)
{
	cout << mp->year << "年  " << mp->memory << "G " << mp->name << endl;
}
int main()
{
	Person *pp = new Person(234,"yar");
	MobilePhone *mp = new MobilePhone;
	pp->show(mp);
	system("pause");
	return 0;
}

class HardDisk
{
public:
	HardDisk();
	friend class Computer;
private:
	int capacity;
	int speed;
	string brand;
};
HardDisk::HardDisk():capacity(128),speed(0),brand("三星"){
}
class Computer
{
public:
	Computer(HardDisk hd);
	void start();
private:
	string userName;
	string name;
	int ram;
	string cpu;
	int osType;
	HardDisk hardDisk;
};
Computer::Computer(HardDisk hd):userName("yar"),name("YAR-PC"),ram(16),cpu("i7-4710"),osType(64)
{
	cout << "正在创建computer..." << endl;
	this->hardDisk = hd;
	this->hardDisk.speed = 5400;
	cout << "硬盘转动...speed = " << this->hardDisk.speed << "转/分钟" << endl;
}
void Computer::start()
{
	cout << hardDisk.brand << " " << hardDisk.capacity << "G" << hardDisk.speed << "转/分钟" << endl;
	cout << "笔记本开始运行..." << endl;
}
int main()
{
	HardDisk hd;
	Computer cp(hd);
	cp.start();
	system("pause");
	return 0;
}

//结构体默认权限为public
struct person
{
	void show();
	string name;
	int age;
};
int main()
{
	person p;
	p.name = "heiren";
	p.age = 666;
	p.show();
	cout <<"name="<< p.name <<" age="<< p.age << endl;
	system("pause");
	return 0;
}

//继承方式为可选项，默认为private，还有public,protected
class 派生类名：[继承方式]基类名
{
	派生类新增加的成员声明;
};

class Base
{
public:
	void show();
protected:
	int aa;
	double dd;
};
void Base::show(){
}
class Person:public Base
{
public:
	using Base::aa;//将基类的protected成员变成public
	using Base::dd;//将基类的protected成员变成public
private:
	using Base::show;//将基类的public成员变成private
	string name;
};
int main()
{
	Person *p = new Person();
	p->aa = 12;
	p->dd = 12.3;
	p->show();//出错
	delete p;
	return 0;
}

class Base
{
public:
	Base(int, double);
	~Base();
private:
	int aa;
	double dd;
};
Base::Base(int a, double d) :aa(a), dd(d)
{
	cout << "Base Class 构造函数!!!" << endl;
}
Base::~Base()
{
	cout << "Base Class 析构函数!!!" << endl;
}
class Person:public Base
{
public:
	Person(int,double,string);
	~Person();
private:
	string name;
};
Person::Person(int a,double d,string str):Base(a,d),name(str)
{
	cout << "Person Class 构造函数!!!" << endl;
}
Person::~Person()
{
	cout << "Person Class 析构函数!!!" << endl;
}
int main()
{
	cout << "创建Person对象..." << endl;
	Person *p = new Person(1,2,"yar");
	cout << "删除Person对象...." << endl;
	delete p;
	system("pause");
	return 0;
}

class 派生类名:继承方式1 基类1,继承方式2 基类2
{
	派生类主体;
};

派生类名(总参数列表)：基类名1(基类参数列表1),基类名2(基类参数列表2),
子对象名1,...(参数列表)
{
	构造函数体;
}`

class  A//虚基类
{
protected:
	int a;
};
class B: virtual public A
{
protected:
	int b;
};
class C:virtual public A
{
protected:
	int c;
};
class D:public B,public C
{
protected:
	int d;
	void show()
	{
		b = 123;
		c = 23;
		a = 1;
	}
};

int a = 66.9;
printf("%d\n", a);//66
float b = 66;
printf("%f\n", b);//66.000000

class  A
{
public:
	virtual void show()
	{
		cout << "A show" << endl;
	}
};
class B:  public A
{
public:
	void show()
	{
		cout << "B show" << endl;
	}
};
int main()
{
	B b;
	b.show();//B show
	A *pA = &b;
	pA->show();//B show 如果show方法前没用virtual声明为虚函数，这里会输出A show
	system("pause");
	return 0;
}

class  A
{
public:
	virtual void show() = 0;
};
class B:  public A
{
public:
	void show()
	{
		cout << "B show" << endl;
	}
};

函数类型 operator运算符(参数列表)
{
	函数体
}
//举个栗子：定义一个向量类，通过运算符重载，可以用+进行运算。
class Vector3
{
public:
	Vector3();
	Vector3(double x,double y,double z);
public:
	Vector3 operator+(const Vector3 &A)const;
	void display()const;
private:
	double m_x;
	double m_y;
	double m_z;
};
Vector3::Vector3() :m_x(0.0), m_y(0.0), m_z(0.0) {}
Vector3::Vector3(double x, double y,double z) : m_x(x), m_y(y), m_z(z) {}
//运算符重载
Vector3 Vector3::operator+(const Vector3 &A) const
{
	Vector3 B;
	B.m_x = this->m_x + A.m_x;
	B.m_y = this->m_y + A.m_y;
	B.m_z = this->m_z + A.m_z;
	return B;
}
void  Vector3::display()const
{
	cout<<"(" << m_x << "," << m_y << "," << m_z << ")" << endl;
}

class Vector3
{
public:
	Vector3();
	Vector3(double x,double y,double z);
public:
	Vector3 operator+(const Vector3 &A)const;
	Vector3 operator++();
	friend Vector3 operator-(const Vector3 &v1, const Vector3 &v2);
	friend Vector3 operator--(Vector3 &v);
	void display()const;
private:
	double m_x;
	double m_y;
	double m_z;
};
Vector3::Vector3() :m_x(0.0), m_y(0.0), m_z(0.0) {}
Vector3::Vector3(double x, double y,double z) : m_x(x), m_y(y), m_z(z) {}
//运算符重载
Vector3 Vector3::operator+(const Vector3 &A) const
{
	Vector3 B;
	B.m_x = this->m_x + A.m_x;
	B.m_y = this->m_y + A.m_y;
	B.m_z = this->m_z + A.m_z;
	return B;
}
Vector3 Vector3::operator++()
{
	this->m_x ++;
	this->m_y ++;
	this->m_z ++;
	return *this;
}
void  Vector3::display()const
{
	cout<<"(" << m_x << "," << m_y << "," << m_z << ")" << endl;
}
Vector3 operator-(const Vector3 &v1,const Vector3 &v2)
{
	Vector3 B(v1.m_x - v2.m_x, v1.m_y - v2.m_y, v1.m_z - v2.m_z);
	return B;
}
Vector3 operator--( Vector3 &v)
{
	v.m_x--;
	v.m_y--;
	v.m_z --;
	return v;
}
int main()
{
	Vector3 v1(1, 2, 3);
	Vector3 v2(2, 3, 2);
	++v1;//v1.operator++(); 作为类成员函数可以显式调用
	v1.display();
	--v2;
	v2.display();
	Vector3 v3 = v1 + v2;// v1.operator+(v2);作为类成员函数可以显式调用
	v3.display();
	Vector3 v4 = v1 - v2;
	v4.display();
	return 0;
}

//前置运算符 ++a --a
operator++()
operator--()
operator++(Vector3 &v)
operator--(Vector3 &v)
//后置运算符 a-- a++
operator++(int)
operator--(int)
operator++(Vector3 &v,int)
operator--(Vector3 &v,int)

String& String::operator=(String &s)
{
  if(this!=&s)
  {
  		delete[] str;
  		int length = strlen(s.str);
  		str = new char[length+1];
  		strcpy(str,s.str);
  }
  return (*this)
}

 friend ostream &operator<<( ostream &output, 
                                       const Vector3 &v )
      { 
         output << "F : " <<v.m_x<< " I : " << v.m_y<<v.m_z;
         return output;            
      }
      friend istream &operator>>( istream  &input, Vector3 &v )
      { 
         input >> v.m_x>> v.m_y>>v.m_z;
         return input;            
      }

operator 类型名()
{
	转换语句;
}
class Vector3
{
public:
	Vector3();
	Vector3(double x,double y,double z);
public:
	Vector3 operator+(const Vector3 &A)const;
	Vector3 operator++();
	friend Vector3 operator-(const Vector3 &v1, const Vector3 &v2);
	friend Vector3 operator--(Vector3 &v,int);
	operator double()
	{
		return m_x + m_y + m_z;
	}
	void display()const;
private:
	double m_x;
	double m_y;
	double m_z;
};
int main()
{
	Vector3 v1(1, 2, 3);
	double d = v1;
	cout << d << endl;//6
	return 0;
}

int  x;
double y;
cin>>x>>y;
//输入 22 66.0  两个数之间可以用空格、制表符和回车分隔数据
char str[10];
cin>>str;//hei ren  字符串中只有hei\0

char c = cin.get();//获取一个字符
while ((c = cin.get()) != EOF)//循环读取，直到换行
{
	cout << c;
}
char ch;
cin.get(ch);
while (cin.get(ch))//读取成功循环
{
	cout << ch;
}
char arr[5];
cin.get(arr, 5, '\n');//输入 heiren  结果 heir\0

char arr0[30],arr1[30],arr2[40];
cin>>arr0;//遇到空格、制表符或回车结束  "Heiren"
cin.getline(arr1,30);//字符数最多为29个，遇到回车结束 " Hello World"
cin.getline(arr2,40,'*');//最多为39个，遇到*结束 "yar"
//输入 Heiren Hello World
//yar*123

int n;
 cin.ignore(5, 'Y');//跳过前5个字符或Y之前的字符，‘Y'优先
 cin >> n;
 //输入1234567  ->  67    1234567Y345->345
//输入2020.2.23
int year,month,day;
cin >> year ;
cin.ignore() >> month ; //用ignore跳过 '.'
 cin.ignore() >> day;
cin.ignore();   //跳过行末 '\n'
 cout<< setfill('0') << setw(2) << month ;//设置填充字符'\0'，输出宽度2
 cout << "-" << setw(2) << day << "-" << setw(4) << year << endl;

cout << setiosflags(ios::fixed) << 12.34 << endl;
cout << resetiosflags(ios::fixed) << setiosflags(ios::scientific | ios::showpos) << 12.34 << endl;

cout.setf(ios::scientific);
cout.precision(8);
cout << 12.23 << endl;//1.22300000e+001

#include <fstream>
ifstream in;
ofstream out;
fstream inout;

#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream inFile("c:\\tmp\\test.txt", ios::in);
    if (inFile)
        inFile.close();
    else
        cout << "test.txt doesn't exist" << endl;
    ofstream oFile("test1.txt", ios::out);
    if (!oFile)
        cout << "error 1";
    else
        oFile.close();
    fstream oFile2("tmp\\test2.txt", ios::out | ios::in);
    if (!oFile2)
        cout << "error 2";
    else
        oFile.close();
    return 0;
}

#include <iostream>
#include <fstream>
using namespace std;
int arr[100];
int main()
{
	int num = 0;
	ifstream inFile("i.txt", ios::in);//文本模式打开
	if (!inFile)
		return 0;//打开失败
	ofstream outFile("o.txt",ios::out);
	if (!outFile)
	{
		outFile.close();
		return 0;
	}
	int x;
	while (inFile >> x)
		arr[num++] = x;
	for (int i = num - 1; i >= 0; i--)
		outFile << arr[i] << " ";
	inFile.close();
	outFile.close();
	return 0;
}

class Person
{
public:
	char m_name[20];
	int m_age;
};
int main()
{
	Person p;
	ofstream outFile("o.bin", ios::out | ios::binary);
	while (cin >> p.m_name >> p.m_age)
		outFile.write((char*)&p, sizeof(p));//强制类型转换
	outFile.close();
	//heiren 烫烫烫烫烫烫啼  
	return 0;
}

Person p;
ifstream inFile("o.bin", ios::in | ios::binary); //二进制读方式打开
if (!inFile)
	return 0;//打开文件失败
while (inFile.read((char *)&p, sizeof(p)))
	cout << p.m_name << " " << p.m_age << endl;
inFile.close();

#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream inFile("a.txt", ios::binary | ios::in); 
    if (!inFile)
        return 0;
    ofstream outFile("b.txt", ios::binary | ios::out);
    if (!outFile) 
    {
        inFile.close();
        return 0;
    }
    char c;
    while (inFile.get(c))  //每读一个字符
        outFile.put(c);  //写一个字符
    outFile.close();
    inFile.close();
    return 0;
}

ostream & seekp (int offset, int mode);
istream & seekg (int offset, int mode);
//mode有三种：ios::beg-开头往后offset(>=0)字节 ios::cur-当前往前(<=0)/后(>=0)offset字节 ios::end-末尾往前(<=0)offect字节
int tellg();
int tellp();
//seekg 函数将文件读指针定位到文件尾部，再用 tellg 函数获取文件读指针的位置，此位置即为文件长度

#include <iostream>
#include <fstream>
//#include <vector>
//#include<cstring>
using namespace std;
class Person
{
public:
	char m_name[20];
	int m_age;
};
int main()
{
	Person p;
	ifstream ioFile("p.bin", ios::in | ios::out);//用既读又写的方式打开
	if (!ioFile) 
		return 0;
	ioFile.seekg(0, ios::end); //定位读指针到文件尾部，以便用以后tellg 获取文件长度
	int L = 0, R; // L是折半查找范围内第一个记录的序号
				  // R是折半查找范围内最后一个记录的序号
	R = ioFile.tellg() / sizeof(Person) - 1;
	do {
		int mid = (L + R) / 2; 
		ioFile.seekg(mid *sizeof(Person), ios::beg); 
		ioFile.read((char *)&p, sizeof(p));
		int tmp = strcmp(p.m_name, "Heiren");
		if (tmp == 0)
		{ 
			cout << p.m_name << " " << p.m_age;
			break;
		}
		else if (tmp > 0) 
			R = mid - 1;
		else  
			L = mid + 1;
	} while (L <= R);
	ioFile.close();
	system("pause");
	return 0;
}

template<class T>或template<typename T>
函数类型 函数名(参数列表)
{
	函数体;
}
template<class T1,class T2,...>//class可以换成typename
函数类型 函数名(参数列表)
{
	函数体;
}
//举个栗子
template<class T> T max(T a, T b)
{
	return a > b ? a : b;
}
int main()
{
	cout <<"max value is "<< max(12,34) << endl;//34
	cout << "max value is " << max(12.4, 13.6) << endl;//13.6
	cout << "max value is " << max(12.4, 13) << endl;//error 没有与参数列表匹配的 函数模板 "max" 实例参数类型为:(double, int)
	return 0;
}

template<class T>//class可以换成typename 模板头
class 类名
{
	函数定义;
};
//多个类型参数和函数模板类似，逗号隔开

template<typename T1, typename T2>  // 模板头  没有分号
class Point {
public:
	Point(T1 x, T2 y) : x(x), y(y) { }
public:
	T1 getX() const;  //成员函数后加const，声明该函数内部不会改变成员变量的值
	void setX(T1 x);  
	T2 getY() const;  
	void setY(T2 y);  
private:
	T1 x;  
	T2 y;  
};
template<typename T1, typename T2>  //模板头
T1 Point<T1, T2>::getX() const  {
	return x;
}
template<typename T1, typename T2>
void Point<T1, T2>::setX(T1 x) {
	x = x;
}
template<typename T1, typename T2>
T2 Point<T1, T2>::getY() const {
	return y;
}
template<typename T1, typename T2>
void Point<T1, T2>::setY(T2 y) {
	y = y;
}
int main()
{
	Point<int, double> p1(66, 20.5);
	Point<int, char*> p2(10, "东经33度");
	Point<char*, char*> *p3 = new Point<char*, char*>("西经12度", "北纬66度");
	cout << "x=" << p1.getX() << ", y=" << p1.getY() << endl;
	cout << "x=" << p2.getX() << ", y=" << p2.getY() << endl;
	cout << "x=" << p3->getX() << ", y=" << p3->getY() << endl;
	return 0;
}

class MyClass
{
public:
		typedef int LengthType;
		LengthType getLength() const
		{
			return this->length;
		}
		void setLength(LengthType length)
		{
			this->length = length;
		}
private:
	LengthType length;
};
template<class T>
void MyMethod(T myclass)
{
	//告诉 c++ 编译器，typename 后面的字符串为一个类型名称，而不是成员函数或者成员变量
	typedef typename T::LengthType LengthType; //
	LengthType length = myclass.getLength();
	cout << "length = " <<length<< endl;
}
int main()
{
	MyClass my;
	my.setLength(666);
	MyMethod(my);//length = 666
	return 0;
}

int a = 123;  //不转换
a = 12.89;  //隐式转换 12（舍去小数部分）
a = (int)"heiren,HelloWorld";  //强制转换（得到字符串的地址） 不同类型之间转换需要强制

//Java 对类型转换的要求比 C/C++ 更为严格，隐式转换只允许由低向高转，由高向低转必须强制转换。
int a = 100;  //不转换
a = (int)12.34;  //强制转换（直接舍去小数部分，得到12）

var a = 100;  //赋给整数
a = 12.34;  //赋给小数
a = "heiren,HelloWorld";  //赋给字符串
a = new Array("JavaScript","React","JSON");  //赋给数组

namespace [命名空间名]//名省略时，表示无名的命名空间
{
	命名空间成员;
}

try
{
	被检查的语句（可以有多个throw语句）;
}
catch(异常信息类型 [变量名])
{
}

try
{
	throw 123;
}
catch (int a)
{
	cout << a << endl;//123
}

int size();
bool empty();

begin()
end()
rbegin()
erase(...)
clear()

front()
back()
push_back();
pop_back();
insert(...);

#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
int main()  {
   vector<int> v;
	v.push_back(1);
	v.push_back(2);
	v.push_back(3);
	v.push_back(4); //1,2,3,4
	vector<int>::iterator p;
	p = find(v.begin(), v.end(), 3); //在v中查找3 若找不到,find返回 v.end()
	if (p != v.end())
		cout << "1) " << *p << endl; //找到了
	p = find(v.begin(), v.end(), 9);
	if (p == v.end())
		cout << "not found " << endl; //没找到
	p = find(v.begin() + 1, v.end() - 1, 4); //在2,3 这两个元素中查找4
	cout << "2) " << *p << endl; //没找到，指向下一个元素4
	int arr[10] = { 10,20,30,40 };
	int * pp = find(arr, arr + 4, 20);
	if (pp == arr + 4)
		cout << "not found" << endl;
	else
		cout << "3) " << *pp << endl;
	return 0;
}