1. Introduction
  2. Variable Data-Type and Operator
    1. Variable
    2. Data Type
    3. Identifier name
    4. Variable Definition in C++
    5. Variable Declaration in C++
    6. Defining Constants
    7. Operator
      1. Arithmetic Operators
      2. Relational Operators
      3. Logical Operators
  3. Control Statement
    1. The if Statement
    2. The if – else statement
    3. The else if statement
    4. Nested if-else
    5. The switch statement
  4. Loop
    1. While loop
    2. Do while loop
    3. For loop
    4. Nested Loop
    5. Break, Continue And Go to label
  5. Function
    1. Declaration function
    2. Non Return Function
    3. Return Function
    4. Function Definition
  6. Array
    1. Declaration Array
      1. One Dimensional Array
      2. Two Dimensional Array
  7. Class and Object

2.5.Variable Declaration in C++ #

There are two types of variable declaration, such as Local Variable and Global Variable.

  • Local Variables

Variables that are declared inside a function or block are local variables. They can be used only by statements that are inside that function or block of code.

Example:

#include<iostream.h>
#include<conio.h>
void main()
{
	int radius=10;
	float area=radius*3.14;
	cout<<"Area of Circle: "<<area;
	getch();
}
  • Global Variables

Global variables are defined outside of all the functions, usually on top of the program. The global variables will hold their value throughout the life-time of your program.

Example:

#include<iostream.h>
#include<conio.h>
int i=2; 
void doubleValue() 
{ 
	i*=5; 
} 
void main() 
{ 
	cout<<"I: "<<i<<endl; 
	doubleValue(); 
	cout<<"Double I: "<<i<<endl; 
	getch(); 
}
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