Programming Basics Chapter 1

Writing Programs

• Involves analyzing a problem, designing a solution, and implementing it using a programming language.
• The development process includes designing algorithms and translating them into code.

Algorithms and Code

• An algorithm lists the steps required to solve a problem and the order of execution.
• Code is the actual writing of the program.

Identifiers

• Identifiers are sequences of characters (letters, digits, underscores) used to name variables and functions.
• Must start with a letter or underscore, not a digit, and cannot be a keyword.
• Examples of valid identifiers: numberOfStudents, _speed. Invalid examples: 23spam, #sign.
• Python is case-sensitive; area, Area, and AREA are different identifiers.
• Descriptive identifiers enhance readability; complete names are preferred over abbreviations.

Naming Conventions

• CamelCase is used for multi-word variable names; first word in lowercase, subsequent words capitalized (e.g., numberOfStudents).
• Use lowercase letters for variable names (e.g., radius, area).

Variables

• Variables reference values in a program that can change.
• Follow rules: start with a letter/underscore, can include letters, numbers, and underscores, and are case-sensitive.

Assignment Statements

• Use = to assign a value to a variable; format: variable = expression.
• Expressions combine values, variables, and operators to evaluate to a result.

Named Constants

• A constant is an identifier that represents a fixed value, providing clarity and avoiding repetition in code.
• Changing a constant value only requires updating it in one location, enhancing maintainability.

Numeric Data Types

• Integer (int): Represents whole numbers.
• Real numbers (float): Represents numbers with fractional parts.

Numeric Operators

• Arithmetic operators include:
  • + Addition
  • - Subtraction
  • * Multiplication
  • / Float Division
  • // Integer Division
  • ** Exponentiation
• Example of float division: 4 / 2 results in 2.0, while 2 / 4 results in 0.5.
• Integer division with // results in an integer (e.g., 5 // 2 gives 2).