#include<iostream>
using namespeace std;
int main()
{
//数据输入,给a赋值
cin>>a;
cout<< <<endl;//<<endl相当与\n
system("pause");
return 0;
}
科学计数法 3e2 >> 3*10 ^2 3E2 >> 3*0.1^2
字块 char a = 'a' 字符char a = "abc"
Ascil码 a>>97 A>65
char str[] = "asdfghjkl"
用string str = "asdfghjkl" 时要#include<string>