what is variable and constant in c

(10) What is Variable?

 Variable is a character or group of character assigned by the programmer to a single memory location and used a in the program as the name of that memory location in order to access the value stored in it.
 Example:-
                                  x=7
                                  X is a variable
                                  Y = x+5 = 7+5=12
                                  Z = y+5 = 12+5=17

Naming rules to defined a variable:- 

            ~first letter must be an alphabet or under s (-)l 

            ~no space or special character except under score allowed in a variable. 

            ~ A variable name in case sensitive a=5, y= a+5 here, a has other value& a has another value. 

            ~A variable name is collection of alphabet, digit or underscore. Ex :- A2=5 A2 - = A2 

                     ( the first letter must be alphabet or underscore) 

            ~ Maximum number of character is a variable may be 8or32 depends on system configuration                                                  ( processor). 

            ~1. abc 2. abc 3. ab$c 4. $abc 5. ab-c 6. 2 ab. 7. mohit kumar. 8. abcd- 

            1. true.

            2. false. 

            3.False. 

            4. false. 

            5. false.  

            6. false.  

            7.false. 

            8. true.

Constant :- It is a fixed value which is used in a programme to perform a task. It may be used to assign a value to variable 

 A constant may be of following types:- 

                                     1. numbers 

                                                    A. integer ( without decimal). 

                                                    B. float (real , with decimal). 

                                     2. character (single alphabet). 

                                     3. string ( group of character). 

                                     4. Boolean ( true or false)