c/c++运算符与精度(部分

double,float,字符型，字符串，bool

#include<string>
#include<iostream>
using namespace std;
int main()
{
	double f1 = 31.415926;
	cout << "f1=" << f1 << endl;//单精度与双精度默认六位有效数字
	float d1 = 31.415926f;     //float 七位有效，double十五~十六位有效
	cout << "d1=" << d1 << endl;


	//字符型
	char a = 12;
	cout <<(int)a<< endl;//98.强制转换,可以输出数字，但是要强转



	//字符串c语言：
	char s1[] = "nihao shijie
";
	cout << s1 <<"大小为" <<sizeof(s1)<< endl;
	//c++版
	string s2 = "buhao shijie
";
	cout << s2 << "大小为" << sizeof(s2) << endl;



	//BOOL类型： true——真(1)    false——假(0)，占用一字节。
	bool flag = true;
	bool a = false;
	cout << "true的值" << flag << endl << "falsed的值" << a << endl;
	cout<<"wei flag fuzhi"<<endl;
	cin>>flag;
	cout<<flag<<endl;


	//输入cin
	string a = "nihao";
	cout << "请输入字符串" << endl;// 字符串输入遇空格停止，后续不计入
	cin >> a;
	cout << a <<endl<< "daxiao" << endl << sizeof(a) << endl;

四种运算符：

//各种运算符：1，算数运算符： +  -  *  /  %  ++  --
	int a = 6;
	int b = -2;
	cout << a/b << endl;
	cout << -6 % 4 << endl;//求余与第一个数的符号有关，都得整型
	cout << a++ <<endl<< a << endl;
	

//2.赋值运算符:+= -= *= /= %= =
	int a = 8;
	a %= 6;
	cout << a << endl;

	//3.比较运算符 >  <  ==  !=  >=  <=
	//int a = 9;
	//int v = 2;
	//cout << (a > v )<< endl;

	//4.逻辑运算符 ！  &&    || 最短作用