//variable scope
#include<iostream>
//global variable
//local variable
int k=0;
//function
//array
//struct
//class
//Macro
int main()
{ //block
   cout<<k;
   int k = 2;
   int j=0;
   {
      int i=0;
   }
   cout<<k;
   cout<<::k;
}
//definition
short 2B
unsigned int 4B
signed long 8B

1B = 0xFF

float
double

unsigned char
string 
bool

int i=10;
//initialization

long b;
b=1200;
//assignement