Tokens in C++

 In C++, a token is the smallest individual unit in a program. The compiler breaks down the source code into these tokens for further processing. Here's a breakdown of the different types of tokens in C++:

1. Keywords

• These are reserved words that have predefined meanings in the C++ language.
• They cannot be used as identifiers (names for variables, functions, etc.).
• Examples: int, float, if, else, for, while, class, public, private

2. Identifiers

• These are names given to different parts of the program, such as variables, functions, objects, and classes.
• They must start with a letter (A-Z or a-z) or an underscore (_).
• Subsequent characters can be letters, digits (0-9), or underscores.
• C++ is case-sensitive, so myVariable and myvariable are different identifiers.
• Examples: x, my_variable, calculateArea, StudentName

3. Constants (Literals)

• These are fixed values that do not change during program execution.
• C++ has several types of constants:
  • Integer constants: Whole numbers (e.g., 10, -5, 0)
  • Floating-point constants: Numbers with decimal points (e.g., 3.14, -2.5, 0.0)
  • Character constants: Single characters enclosed in single quotes (e.g., 'A', 'z', '5')
  • String constants: Sequences of characters enclosed in double quotes (e.g., "Hello", "C++ Programming")
  • Boolean constants: true or false

4. Operators

• These are symbols that perform specific operations on operands (data).
• C++ has various types of operators:
  • Arithmetic operators: + (addition), - (subtraction), * (multiplication), / (division), % (modulus)
  • Relational operators: == (equal to), != (not equal to), > (greater than), < (less than), >= (greater than or equal to), <= (less than or equal to)
  • Logical operators: && (logical AND), || (logical OR), ! (logical NOT)
  • Assignment operators: = (assignment), += (add and assign), -= (subtract and assign), etc.
  • Bitwise operators: Perform operations on individual bits (e.g., &, |, ^, ~, <<, >>)

5. Punctuators

• These are special symbols that have syntactic meaning in C++.
• Examples:
  • ; (semicolon): Ends a statement
  • , (comma): Separates items in a list
  • () (parentheses): Used in function calls, expressions, etc.
  • {} (curly braces): Define blocks of code
  • [] (square brackets): Used for array indexing

Example

C++

int age = 25; // This statement has the following tokens:
              // - int (keyword)
              // - age (identifier)
              // - = (operator)
              // - 25 (constant)
              // - ; (punctuator)

Understanding tokens is fundamental to grasping the structure and syntax of C++ programs. They are the basic building blocks that the compiler uses to interpret and execute your code.