Statement Intro

Any legal expression can be a statement. For example: 
; 
3;
7 + sqrt(121);
The first is an empty statement, the second is a simple expression statement. The third is an expression containing a function. A block statement is a sequence of zero or more statements enclosed between curly braces: 
{             
     int x = 3;
     cout << x << endl;
     {
           int x = 5;
          cout << x << endl;
     }
     cout << x << endl;
}
The block statement above contains four statements, the third of which is another block statement. Notice that: 
int x = 3;
defines a variable which is local to the block where it is defined. Also, the definition of a variable bearing the same name within an inner block, as in: 
int x = 5;
makes this second variable available only in the inner block, while the other x variable is inaccessible in such a block.

Example


#include <iostream>
#include <cmath>
using namespace std;
 
int main()
{   
     ;  // any legal expression can be a statement
     3;
     7 + sqrt(121); // ok, most compilers give you a warning

// block statement
     {             
           int x = 3; // this variable is local to this (outer) block
           cout << x << endl;
           {
                int x = 5; // this variable is local to this (inner) block. The is no way to access the outer x from here
                cout << x << endl;
           }
           cout << x << endl;
     }
}

Output

3
5
3