what are the tokens and lexems in compiler?
  In compiler design, tokens and lexems are the basic building blocks used to represent the source code being compiled.

Tokens:

Tokens are the smallest units of meaningful information in the source code. They are created by the lexical analyzer (lexer) during the scanning process, and they represent a single unit of meaning, such as a keyword, identifier, operator, or literal.

Examples of tokens include:

* Keywords (e.g. "if", "while", "for")
* Identifiers (e.g. variable names, function names)
* Operators (e.g. "+"., "-", "*", "/")
* Literals (e.g. numbers, strings, characters)

Lexems:

Lexems are the actual characters or sequences of characters that make up the source code. They are the raw material that the lexical analyzer uses to create tokens.

Examples of lexems include:

* Letters (e.g. "a", "b", "c")
* Digits (e.g. "1", "2", "3")
* Special characters (e.g. "#", "$", "%")
* Sequences of characters (e.g. "hello", "goodbye")

The lexical analyzer takes the source code as input and produces a
In the context of compilers and programming languages, **tokens** and **lexemes** are fundamental concepts related to the process of lexical analysis, which is the first phase of compilation.

### Tokens:
- A **token** is a categorized block of text that represents a basic element of the language's syntax. Tokens are the output of the lexical analysis phase and are used in the subsequent phases of compilation (like parsing).
- Each token typically consists of a type (also known as a token class) and a value. The type indicates what kind of syntactic element it represents (e.g., keyword, identifier, operator, literal, etc.), while the value is the actual text or data that corresponds to that token.
- For example, in the code snippet `int x = 10;`, the tokens might be:
  - `int` (keyword)
  - `x` (identifier)
  - `=` (assignment operator)
  - `10` (integer literal)
  - `;` (semicolon)

### Lexemes:
- A **lexeme** is the actual string of characters in the source code that corresponds to a token. It is the specific sequence of characters that the lexer recognizes and classifies as a token.
- Continuing with the previous example, the lexemes in the code `int x = 10;` would be:
  - `int` (lexeme for the keyword)
  - `x` (lexeme for the identifier)
  -