Variable Scope in C++ language.

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Variable Scope in C++ language.


There are three places, where variables can be declared.





  1. Local variables.

  2. Global variables.

  3. Formal parameters.


1.Local variables.

Variables that are declared inside a function or block are local variables. They are not used outside of a function.


void function1()
{
int x=10;//local variable
}

2.Global variables

A variable that is declared outside the function or block is called a global variable. Any function can change the value of the global variable. It is available to all the functions.


int value=20;//global variable
void function1()
{
int x=10;//local variable
}


#include <iostream>
using namespace std;
 
// Global variable declaration:
int p;
 
int main () {
   // Local variable declaration:
   int x, y;
 
   // actual initialization
   x = 10;
   y = 20;
   p = x + y;
  
   cout << p;
 
   return 0;
}

Initializing Local and Global Variables

A local variable is not initialized by the system, you must initialize it yourself. Global variables are initialized automatically by the system. They are.

Data Type Initialize

int

0

char

'\0'

float

0

double

0

pointer

NULL

3.Formal parameters.

The identifier used in a method to stand for the value that is passed into the method by a caller.




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