Pseudocode – Variables, Constants, and Data Types

 Atomic Type Names  

- INTEGER: Whole numbers.  

- REAL: Numbers with fractional parts.  

- CHAR: A single character.  

- STRING: A sequence of zero or more characters.  

- BOOLEAN: Logical values `TRUE` or `FALSE`.  

- DATE: A valid calendar date.  

Literals  

- Integer: Written in denary, e.g. `9`, `-3`.  

- Real: Must have digits on both sides of the decimal, e.g. `4.7`, `-3.0`.  

- Char: Single character in single quotes, e.g. `'x'`, `'C'`, `'@'`.  

- String: Enclosed in double quotes, e.g. `"This is a string"`, `""`.  

- Boolean: `TRUE`, `FALSE`.  

- Date: Format `dd/mm/yyyy`. Best practice: explicitly state type `DATE` and explain format.  

Identifiers  

- Names for variables, constants, procedures, and functions.  

- Written in mixed case (camelCase or PascalCase).  

- Rules:  

  - Must start with a letter.  

  - Can contain letters (A–Z, a–z) and digits (0–9).  

  - No underscores, accented letters, or special characters.  

- Single letters may be used for array indices or coordinates.  

- Case insensitive: e.g. `CountDown` and `Countdown` should not be separate variables.  

Variable Declarations  

```

DECLARE <identifier> : <data type>

Constants  

- Declared at the beginning of pseudocode (unless scope restriction is needed).  

CONSTANT <identifier> = <value>

- Only literals can be used as constant values.  

- Cannot assign variables, other constants, or expressions.  

Assignments  

- Assignment operator: `<--`  

<identifier> <-- <value>

- Identifier must be a variable.  

- Value must evaluate to the same data type as the variable.