IDEs: Features and Tools

This lesson covers Integrated Development Environments (IDEs) — what they are and the tools they provide to help programmers write, test, and debug code. This is part of OCR J277 Section 1.5.3.

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What Is an IDE?

An IDE (Integrated Development Environment) is a software application that provides a comprehensive set of tools for writing, testing, and debugging programs — all within a single interface.

Instead of using separate tools for writing code, compiling it, and finding errors, an IDE bundles everything together for efficiency.

Examples of IDEs

IDE	Language(s)
IDLE	Python
PyCharm	Python
Visual Studio	C#, C++, VB.NET, and more
Visual Studio Code	Many languages (via extensions)
Eclipse	Java
Thonny	Python (education-focused)

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Key Features of an IDE

OCR J277 requires you to know about these IDE features:

1. Code Editor

The code editor is where programmers write and edit their source code. It provides features that make coding easier and less error-prone:

Feature	Description
Syntax highlighting	Colours different elements of code (keywords, strings, variables, comments) to improve readability
Auto-complete / IntelliSense	Suggests completions as you type (e.g. function names, variable names)
Auto-indentation	Automatically indents code blocks to maintain proper structure
Line numbering	Numbers each line of code for easy reference
Bracket matching	Highlights matching opening and closing brackets

Example with syntax highlighting (Python):

# This is a comment (usually green or grey)
name = input("Enter your name: ")   # string in quotes (usually red or orange)
if name == "Alice":                  # keyword 'if' (usually blue or purple)
    print("Hello, Alice!")           # function 'print' (usually yellow)
else:
    print(f"Hello, {name}!")

Syntax highlighting makes it much easier to spot errors — for example, if a string is not properly closed with a quotation mark, the colouring will look wrong.

2. Debugger

A debugger helps programmers find and fix errors (bugs) in their code. Key debugging tools include:

Tool	Description
Breakpoints	Mark a line where execution will pause, allowing you to inspect the program state
Step-through	Execute the program one line at a time to observe behaviour
Watch window	Monitor the values of specific variables as the program runs
Call stack	Shows the sequence of function calls that led to the current point
Variable inspector	Displays the current values of all variables

Example: Using a Debugger

total = 0
for i in range(1, 6):
    total += i    # Set a breakpoint here to watch 'total' change
print(total)

By setting a breakpoint on line 3 and using step-through, you can watch the value of total change with each iteration: 1, 3, 6, 10, 15.