C++基础一初始化

#include <iostream>

#include <string>

using namespace std;

 

//单行 注释

/*多行注释*/

 

 

//常量定义

#define Month 12;

#define Day  31;

/*main为c++的入口函数*/

int main()

{

//变量定义

char b = 'B';

int a = 10;

const int hours = 24;

const bool flags = true;

 

cout << "hello world " << endl;

cout << "a = " << a << endl; 

cout << "b = " << b << endl;

cout << "
";

cout << "
";

cout << "
";

cout << "
";

cout << "
";

cout << "
";

 

float second = 60.0009f; // 单精度浮点

 

cout << "年份 ="<< Day;

cout << "月份 =" << Month;

cout << "小时 =" << hours;

cout << "
"; 

cout << "one minute has " <<second << " s";

cout << "
";

cout << "";

cout << "";

int Times = hours *  Month;

cout << "Month * Hours ==" << Times;

cout << "
";

cout << "
";

cout << "
";

cout << "
";

cout << "
";

 

//sizeof关键字:统计字节数

cout << "short占空间:" << sizeof(short);

cout << "int占空间:" << sizeof(int); 

cout << "long占空间:" << sizeof(long);

cout << "long long 占空间:" << sizeof(long long);

cout << "Month 占空间：" << sizeof Month;

cout << "second占空间：" << sizeof second;

cout << "char 占空间:" << sizeof(char);

cout << "
";

cout << "
";

cout << "
";

 

//字符型

char ch = 'a'; //只能有一个变量,单引号

cout << ch << endl;

cout << sizeof ch << endl;

cout << int(ch) << endl; //字符串转换为ASCII码值

 

 

//字符串型

char s1[] = "this is that ";//C >字符数组，双引号

string s2 = "this is not";//C++ >字符数组，双引号。头文件标识#include <string>

cout << s1 << endl;

cout << s2 << endl;

 

//布尔类型

bool flag = true;

bool unflag = false;

cout << flag << endl; //0

cout << unflag << endl; //1

cout << sizeof flag << endl;

 

/*

//cin 数据输入：从键盘获取输入

int mya = 0;

cout <<"How old are u ? " << endl;

cin >> mya;

cout << "U are " << mya<<" years old "<<endl;

string talk = "";

cout << "What did u say?" << endl;

cin >> talk;

cout << "U said :" << talk << endl;

cout << "
" << endl;

cout << "
" << endl;

cout << "
" << endl;

*/

 

 

 

//运算符

int a1 = 10;

int a2 = 20;

int a1_a2 = a1 + a2;

cout << a1_a2 << endl;

 

 

 

//递增运算符

int a1 = 30;

a1++;

cout << a << endl;

 

system("pause");

return 0;