C Tokens
Tokens is the most important element to be used in creating a program in C. We can defined the tokens as the smallest individual element in C.
We can say that tokens in C is the building block or the basic component for creating a program in C language
Classification of tokens in C
Tokens in C language can be divided into the following categories-
- Keywords in C
- Identifiers in C
- Strings in C
- Operators in C
- Constant in C
- Special characters in C
Keywords in C
Keywords are pre-defined or pre-reversed words and having some special meaning. We cannot use these keywords as a variable names. If we use these words as a variable names, it means we are trying to change its special meaning.
C language supports 32 keywords given below.
| auto | double | int | struct |
| break | else | long | switch |
| case | enum | register | typedef |
| char | extern | return | union |
| const | float | short | unsigned |
| continue | for | signed | void |
| do | while | if | goto |
| static | default | volatile | sizeof |
Identifiers in C
Identifiers are used for naming variables, functions, arrays, structures, etc. Identifiers in C are the user-defined words. It can be composed of uppercase letters, lowercase letters, underscore, or digits. Identifiers cannot be used as keywords.
Rules for naming identifiers in C are given below:
- The first character of an identifier should be either an alphabet or an underscore.
- It should not begin with any numerical digit.
- Identifiers are case sensitive.
- Identifier must be unique.
- Commas or blank spaces cannot be specified within an identifier.
- Keywords cannot be represented as an identifier.
- The length of the identifiers should not be more than 31 characters.
Strings in C
String is an one-dimensional array of characters having null character '\0' at the end of the string. This null character is used for terminate array. Strings in C are enclosed within double quotes, while characters are enclosed within single characters. The size of a string is a number of characters that the string contains.
Constant in C
A constant is value assigned to the variable that will never change during the program execution. It means the value remain unchanged.
There are two ways to declare a constant.
- Using const keyword
We can use variable PI anywhere in the program.
- Using #define pre-processor
It is another way to make a constant variable. PI will remain same during the execution of program.
Operator in C
C operators are symbols that are used to perform mathematical or logical manipulations. The C programming language is rich with built-in operators. These operators are applied on operands. An operand is a data item at which operation is performed. On the basis of numbers of operand, operators are classified into two categories.
1. Unary Operator
A unary operator is an operator applied to the single operand. For example: increment operator (++), decrement operator (--), sizeof, (type)*.
2. Binary Operators
The binary operator is an operator applied between two operands. The following is the list of the binary operators:
- Arithmetic Operators
- Relational Operators
- Shift Operators
- Logical Operators
- Bitwise Operators
- Conditional Operators
- Assignment Operator
- Misc Operator
