Python Fundamentals: Syntax, Variables, Data Types, and Operators

Python Fundamentals: Syntax, Variables, Data Types, and Operators

Why Python Matters for This Program

Python is one of the most widely used programming languages in web development, automation, and data work. The PCEP (Certified Entry-Level Python Programmer) exam, issued by the Python Institute, validates that you understand Python 3 fundamentals. This lesson covers the core building blocks tested in PCEP exam objective PE1: basic computer programming concepts and Python essentials.

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Python Syntax Basics

Python uses indentation to define blocks of code instead of curly braces. This is not optional — incorrect indentation causes an `IndentationError` and your script will not run. Use four spaces per level; do not mix tabs and spaces.

A Python script is a plain-text file saved with the `.py` extension. You can run it from the terminal with `python3 script.py`, or execute statements one at a time in the REPL (Read-Evaluate-Print Loop) by typing `python3` at the command line.

Comments begin with `#`. Python ignores everything after `#` on that line. Use comments to explain your intent.

```python

print("Hello, world!") # inline comment

```

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Variables and Naming Rules

A variable is a named storage location for a value. In Python you create one with a simple assignment:

```python

temperature = 98.6

city = "Chicago"

is_online = True

```

Naming rules (these are enforced by the language):

• Must start with a letter or underscore, never a digit.
• Can contain letters, digits, and underscores.
• Case-sensitive: `Score` and `score` are different variables.
• Cannot use Python keywords such as `if`, `while`, or `return`.

Convention (not enforced, but expected in professional code): use snake_case for variable names (`miles_per_hour`, not `MilesPerHour`).

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Primitive Data Types

Python has five primitive types you must know for PCEP:

| Type | Example | Notes |

|------|---------|-------|

| `int` | `42`, `-7` | Whole numbers, no size limit in Python 3 |

| `float` | `3.14`, `-0.5` | Decimal numbers, stored in IEEE 754 double precision |

| `str` | `"hello"`, `'world'` | Text, enclosed in single or double quotes |

| `bool` | `True`, `False` | Must be capitalized; subclass of `int` (`True == 1`, `False == 0`) |

| `NoneType` | `None` | Represents the absence of a value |

Use `type()` to check a value's type: `type(3.14)` returns `<class 'float'>`.

Type casting converts one type to another:

• `int("5")` → `5`
• `float(3)` → `3.0`
• `str(42)` → `"42"`
• `bool(0)` → `False`; `bool(1)` → `True`

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Operators

Arithmetic operators perform math:

| Operator | Meaning | Example | Result |

|----------|---------|---------|--------|

| `+` | Addition | `7 + 3` | `10` |

| `-` | Subtraction | `7 - 3` | `4` |

| `` | Multiplication | `7 3` | `21` |

| `/` | True division | `7 / 2` | `3.5` |

| `//` | Integer (floor) division | `7 // 2` | `3` |

| `%` | Modulo (remainder) | `7 % 2` | `1` |

| `` | Exponentiation | `2 8` | `256` |

Note: `` applied to a string repeats it: `"ab" 3` gives `"ababab"`.

Comparison operators return a `bool`:

`==`, `!=`, `<`, `>`, `<=`, `>=`

Logical operators combine boolean expressions:

• `and` — True only if both sides are True
• `or` — True if at least one side is True
• `not` — reverses the boolean value

Python uses short-circuit evaluation: with `and`, if the left side is False, the right side is never evaluated; with `or`, if the left side is True, the right side is skipped.

Bitwise operators work on integer bits:

`&` (AND), `|` (OR), `^` (XOR), `~` (NOT), `<<` (left shift), `>>` (right shift).

Operator precedence (highest to lowest, simplified): `**` → unary `~`, `+`, `-` → `*`, `/`, `//`, `%` → `+`, `-` → shifts → `&` → `^` → `|` → comparisons → `not` → `and` → `or`. When in doubt, use parentheses.

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Formatted String Output (f-strings)

F-strings let you embed expressions inside string literals:

```python

name = "Alex"

score = 95

print(f"Student {name} scored {score} points.")

```

You can control decimal places: `f"{value:.2f}"` rounds to two decimal places.

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Safety Note: Professional Coding Practices

While Python development does not involve physical hazards such as electrical work, professional responsibility still applies:

• Never hard-code credentials (passwords, API keys) in scripts. Use environment variables or configuration files excluded from version control.
• Validate and sanitize all user input before processing it to prevent logic errors or security vulnerabilities.
• Save your work frequently and use version control (Git) so that mistakes are recoverable.
• Keep your Python environment and packages updated to avoid known vulnerabilities.

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Connecting to the PCEP Exam

PECAP exam objective PE1 covers computer programming basics, Python's role as an interpreted language, literals, variables, operators, and basic I/O. Every concept in this lesson maps directly to PE1. When you sit the PCEP exam, expect questions that ask you to predict the output of short code snippets — exactly the skill you practice in today's REPL drill.