Variables
Variables are the basic entities in a program that are used to identify different values. A variable can be declared as :
type variable-name;
Initialize a variable
int a = 10; // 10 is assigned to a char c = 'x'; // x is assigned to c
When declaring two or more variables of the same type using a comma-separated list, you can give one or more of those variables an initial value. For example:
int a, b = 8, c = 19, d; // b and c have initializations
Dynamic Initialization
int a=10; int b=20; int c = a+b; // dynamic initialization
Scope and Lifetime of Variables
there are mainly two types of lifetime of variable, one is global variables and other is local variables. They are explained as :
Global Variables : Global variables are valid throughout the program, they can be modified anywhere in the program.
Local Variables : Local variables are valid throughout the Block ( between { and }), they can be modified anywhere in the block only and not visible outside block. Example is as follows :
public class GlobalAndLocal {
public static void main(String[] args) {
int gVariable = 20; // gVariable will be global to the main function here
{ // block starting here
int lVariable = 10; // local to this block only
System.out.println("Global Variable " + gVariable);
gVariable = 100; // modifying global variable assign 100 to gVariable
System.out.println("Global Variable again " + gVariable);
System.out.println("Local Variable lVariable" + lVariable);
}// block ending here
System.out.println("Local Variable lVariable" + lVariable); /* will give
error as lVariable is not known here, scope of lVariable is only to the
upper block */
}
}
