Keywords, Identifiers, Variable & Constants in C.

what are keywords?

• keywords are predefined words. keywords have some special meaning.
• keywords are part of the syntax. they cannot be used as an identifier.

for example: int amount;

int is a keyword that indicates amount is an integer type of variable.

type of keyords:

Identifiers:

• identifiers must be unique.
• identifiers are created to give a unique names.

Example:

char name;

int balance;

C variable:

• in programming, a variable is a cantainer to hold data.
• To indicate the storage area, each variable should be given unique name.

example: int number = 20;

• number is a variable of int type, here the variable is catained integer value 20.

Constants:

if you want to define a variable whose variable cannot be changed, you can use the const keyword.

const number = 20;

• number is a symbolic constat.
• its value cannot be changed.

const pi = 3.14;

pi = 2.14; //error