Declaration of Variables:

Variables are declared as follows:

int a;

float b;

Assigning value to variables:

int a = 100; Declaring and assigning is called initialization.

float b; Declaring a variable b.

b = 123.456; Assigning value to b.

int a=b=c;

Dynamic initialization of variables

int main ( )

{int a = strlen("apple");

cout<<"Total character in the string is"<

return 0;

}

Variables can be declared and initialized at the same time. int main ( )

{int a,b;

cin>>a>>b;

int c=a+b;

cout<<"c is" <

}

In C++  variables  can be declared  anywhere  in  the program  which  will  allow  to do dynamic initialization.  Remember for dynamic initialization the variables must be declared prior to dynamic initialization of new variable.

Reference Variable:

Syntax to define a reference variable is

datatype &reference_variable_name = variable_name;

int y;

int &x = y;

Now the value of x and y will be the same and also if any one of the value is changed the

change will be reflected in the other variable. y =10; Now x is also 10.

x = 20; Now y is also 20.

y = x + 10; Now x and y is 30.

Reference through pointer variable:

int x;

int *ptr = &x;

int &y = *ptr;  This is equivalent to int &y=x;

In function it is known as call by reference void f_ref(int &x)

{x = x +10;

}

int main ( )

{int m =10; f_ref(m); return 0;

}