SQA Introduction to Programming

What is a programming language?
A programming language is a formal set of rules and vocabulary used to write instructions that a computer can understand and execute. Examples include Python, Java, and C++.
What is syntax?
Syntax refers to the set of rules that define how code must be structured and written in a programming language. For example, forgetting a semicolon in C++ is a syntax error.
What is a compiler?
A compiler is a program that translates code written in a high-level programming language (like C++ or Java) into machine code (binary) that the computer can run directly.
What is an interpreter?
An interpreter executes code line by line, translating and running it immediately (e.g., Python). Unlike a compiler, it does not create a standalone executable file.
What is a variable?
A variable is a named container in a program that stores data (e.g., numbers, text) which can be modified or reused during execution.
What is a data type?
A data type defines the kind of value a variable can hold, such as integers (int), decimals (float), text (string), or true/false (boolean).
What is a constant?
A constant is a fixed value that cannot be changed during program execution. For example, PI = 3.14 remains constant throughout the program.
What is an operator?
An operator performs actions on values or variables, such as arithmetic (+, -), comparison (==, >), or logical operators (AND, OR).
What is an expression?
An expression is a combination of variables, operators, and values that produces a result. For example, 5 + 3 * 2 evaluates to 11.
What is a statement?
A statement is a complete instruction in a program that performs an action, like assigning a value (x = 10) or calling a function.
What is a function?
A function is a reusable block of code that performs a specific task. For example, a calculateSum() function might add two numbers.
What is a parameter?
A parameter is a variable listed in a function’s definition that receives data when the function is called. For example, def greet(name): has name as a parameter.
What is a return value?
A return value is the result a function sends back after it completes its task. For example, a square(4) function might return 16.
What is a loop?
A loop repeats a block of code multiple times until a condition is met. Examples include for loops (fixed iterations) and while loops (condition-based).
What is a conditional statement?
A conditional statement runs different code blocks based on whether a condition is true or false. For example: if (age >= 18) { ... } else { ... }.
What is an array?
An array is a collection of items stored in contiguous memory locations. For example, numbers = [1, 2, 3] stores three integers.
What is a string?
A string is a sequence of characters (text) enclosed in quotes. For example, name = "Alice" is a string variable.
What is a pointer?
A pointer is a variable that stores the memory address of another variable. It is used for direct memory manipulation, common in languages like C/C++.
What is object-oriented programming (OOP)?
OOP is a programming paradigm that organizes code into reusable "objects" containing data (attributes) and behaviors (methods).
What is a class?
A class is a blueprint for creating objects in OOP. For example, a Car class might define attributes like color and methods like drive().
What is an object?
An object is an instance of a class. For example, myCar = Car("red") creates an object from the Car class with the color "red".
What is inheritance?
Inheritance allows a class (child) to inherit properties and methods from another class (parent). For example, a Dog class can inherit from an Animal class.
What is encapsulation?
Encapsulation is the practice of bundling data and methods within a class and restricting direct access to internal details for security and simplicity.
What is polymorphism?
Polymorphism lets objects of different classes be treated as objects of a common superclass. For example, a Circle and Square can both have a draw() method.
What is abstraction?
Abstraction simplifies complex systems by hiding unnecessary details and exposing only essential features. For example, a user interacts with a car’s steering wheel but not its engine mechanics.
What is debugging?
Debugging is the process of identifying and fixing errors (bugs) in code to ensure the program works as intended.
What is an Integrated Development Environment (IDE)?
An IDE is a software tool that combines code editing, debugging, and compiling features into one interface. Examples include Visual Studio Code and PyCharm.
What is pseudocode?
Pseudocode is a plain-language outline of a program’s logic, written to plan algorithms before coding. It uses simple syntax like "IF temperature > 30 THEN print 'Hot'".
What is an algorithm?
An algorithm is a step-by-step procedure to solve a problem. For example, a recipe to bake a cake is an algorithm.
What is a comment?
A comment is a note in code that explains its purpose. It is ignored by the compiler/interpreter. For example: // This function calculates the sum.

Types of Programming Languages

How are programming languages categorized into low-level and high-level?
Low-level languages (e.g., machine code, assembly) interact directly with hardware and are difficult for humans to read. High-level languages (e.g., Python, Java) use human-readable syntax and require translation (compilation/interpretation) to run.
What is machine language, and why is it considered the lowest level?
Machine language consists of binary code (0s and 1s) that a computer’s CPU executes directly. It is hardware-specific and not human-friendly.
What is an assembly language?
Assembly language uses symbolic codes (e.g., MOV, ADD) to represent machine instructions. It is slightly more readable than machine code but still requires an assembler to translate it.
Why are high-level languages preferred for modern programming?
High-level languages are easier to write, read, and debug due to English-like syntax. They also abstract hardware details, making code portable across devices.
What is the difference between a compiled and an interpreted language?
Compiled languages (e.g., C++) are translated entirely into machine code before execution. Interpreted languages (e.g., Python) are translated line by line at runtime.
Name examples of high-level programming languages and their common uses.
- Python: Data science, web development.
- Java: Enterprise applications, Android apps.
- JavaScript: Web development (client-side scripting).

Language Paradigms

What is a programming paradigm?
A paradigm is a style or approach to programming. Examples include procedural (step-by-step instructions), object-oriented (objects and classes), and functional (mathematical functions).
How does procedural programming differ from object-oriented programming (OOP)?
Procedural programming focuses on functions and procedures, while OOP organizes code into reusable objects with data and methods.
What is a scripting language?
Scripting languages (e.g., Python, JavaScript) automate tasks or control software applications. They are often interpreted and used for quick prototyping.

Language Features & Design

What is portability in programming languages?
Portability refers to a program’s ability to run on different systems with minimal changes. High-level languages are more portable than low-level ones.
Why is syntax important in a programming language?
Syntax defines the rules for writing valid code. Incorrect syntax (e.g., missing brackets) prevents the program from running.
What does semantics mean in programming?
Semantics refers to the meaning of code. Even if syntax is correct, logical errors (incorrect semantics) can cause unintended behavior.
What is memory management in programming?
Memory management involves allocating and deallocating memory during program execution. Low-level languages (e.g., C) require manual management, while high-level languages (e.g., Java) automate it.

Language Translation & Execution

What role does a compiler play in high-level languages?
A compiler translates the entire high-level code into machine code before execution, producing an executable file (e.g., .exe).
How does an interpreter work differently from a compiler?
An interpreter translates and executes code line by line, stopping at errors immediately. This allows for faster debugging but slower execution.
What is a hybrid language?
Hybrid languages (e.g., Java) combine compilation and interpretation. Java code is compiled into bytecode, which is then interpreted by the JVM (Java Virtual Machine).

Language Selection & Purpose

Why might a programmer choose C over Python?
C offers direct hardware control and faster execution for system-level programming (e.g., operating systems). Python prioritizes readability and ease of use for general-purpose tasks.
What is a domain-specific language (DSL)?
A DSL is tailored for a specific task (e.g., SQL for databases, HTML for web pages). It is less versatile but highly efficient in its domain.

Here’s a categorized set of questions focused on compilers, interpreters, and related tools, designed for revision and clarity:

1. Language Translation Tools

What is a compiler?
A compiler translates entire source code (e.g., C++, Java) into machine-readable code (executable file) before execution.
What is an interpreter?
An interpreter translates and executes code line by line (e.g., Python, JavaScript) without creating a standalone executable.
What is an assembler?
An assembler converts assembly language (human-readable low-level code) into machine code.
What is the difference between a compiler and an interpreter?
A compiler translates all code at once, while an interpreter translates and runs code line by line. Compiled code runs faster; interpreted code is easier to debug.
What is a hybrid approach to language translation (e.g., Java)?
Java uses both a compiler and interpreter: code is compiled into bytecode, which is then interpreted by the Java Virtual Machine (JVM).
What is a linker?
A linker combines compiled code files and libraries into a single executable program.
What is a preprocessor?
A preprocessor modifies source code before compilation (e.g., #include in C adds library code).

2. Execution Process

What is source code?
Source code is the human-readable program written in a high-level language (e.g., Python, C).
What is object code?
Object code is machine-readable code produced by a compiler but not yet executable (requires linking).
What is machine code?
Machine code is binary (0s and 1s) directly executed by the CPU.
Why do compiled languages need an executable file?
The executable contains fully translated machine code ready to run without recompilation.
Why do interpreted languages not generate executables?
Interpreted languages translate code at runtime, so no standalone file is created.

3. Development Tools

What is an IDE (Integrated Development Environment)?
An IDE combines tools like a code editor, compiler, and debugger (e.g., Visual Studio, PyCharm).
What is a debugger?
A debugger helps identify and fix errors by allowing step-by-step code execution and variable inspection.
What are build tools (e.g., Make, Gradle)?
Build tools automate compiling, linking, and packaging code into executables.
What is version control (e.g., Git)?
Version control tracks code changes, enabling collaboration and reverting to previous versions.

4. Compiled vs. Interpreted Languages

Give examples of compiled languages.
C, C++, Rust, Go.
Give examples of interpreted languages.
Python, JavaScript, Ruby.
What is Just-In-Time (JIT) compilation?
JIT compiles code during execution for speed (used in Java, .NET).
Why might Python be slower than C++?
Python is interpreted line by line, while C++ is precompiled to optimized machine code.

5. Error Handling & Tools

What is a syntax error?
A syntax error occurs when code violates language rules (e.g., missing : in Python).
What is a runtime error?
A runtime error occurs during execution (e.g., dividing by zero).
How does an interpreter help in debugging?
It stops at the first error encountered, making it easier to locate issues.
What are breakpoints in debugging?
Breakpoints pause code execution at specific lines to inspect variables and logic.

6. Advanced Concepts

What is cross-compilation?
Compiling code on one system to run on another (e.g., compiling for Android on a Windows PC).
What is bytecode (e.g., Java, Python)?
Bytecode is an intermediate code (not machine code) executed by a virtual machine (e.g., JVM).
What is garbage collection?
Automatic memory management in languages like Java/Python to free unused memory.

Category 8: Practical Scenarios

When would you choose a compiled language over an interpreted one?
For performance-critical tasks (e.g., game engines, operating systems).
Why might a beginner prefer an interpreted language like Python?
Easier debugging, no compilation step, and simpler syntax.
What tool would you use to track changes in your code over time?
Version control systems like Git.

Category 1: Compilers

What is a compiler?
A compiler translates entire source code (e.g., C, C++) into machine code or an executable file before the program runs.
What are the key phases of a compiler?
Lexical analysis, syntax parsing, semantic analysis, code optimization, and code generation.
Why do compiled programs run faster than interpreted ones?
Compiled code is pre-optimized into machine code, while interpreted code is translated line by line during runtime.
What is a cross-compiler?
A compiler that generates machine code for a different operating system or hardware (e.g., compiling Android apps on Windows).
What is an ahead-of-time (AOT) compiler?
A compiler that translates code before runtime (e.g., C++ compilers), unlike JIT (Just-In-Time) compilers.

Category 2: Interpreters

What is an interpreter?
An interpreter executes code line by line, translating and running it during runtime (e.g., Python, JavaScript).
Why are interpreters useful for debugging?
They stop execution at the first error, making it easier to locate and fix bugs.
What is a scripting language?
A language designed for quick execution and automation, often interpreted (e.g., Python, Ruby).
What is the downside of using an interpreter?
Slower execution speed compared to compiled languages, as code is translated at runtime.

Category 3: Hybrid Approaches

How does Java use both compilation and interpretation?
Java code is compiled into bytecode, which is then interpreted by the JVM (Java Virtual Machine).
What is Just-In-Time (JIT) compilation?
JIT compiles code into machine language during runtime to improve performance (used in Java, .NET).
What is bytecode?
Intermediate code that is not machine-specific (e.g., Java .class files, Python .pyc files).

Category 4: Development Tools

What is an IDE?
An Integrated Development Environment (e.g., Visual Studio, PyCharm) combines tools like editors, compilers, and debuggers.
What is a debugger?
A tool for pausing code execution, inspecting variables, and fixing errors (e.g., breakpoints in VS Code).
What is a build tool (e.g., Make, Gradle)?
A tool that automates compiling, linking, and packaging code into executables.
What is a linter?
A tool that analyzes code for stylistic and syntax errors (e.g., ESLint for JavaScript).

Category 5: Execution & Errors

What is a syntax error?
An error caused by violating language rules (e.g., missing semicolons in C).
What is a logical error?
A bug where code runs but produces incorrect results (e.g., wrong formula in a calculation).
What is a runtime error?
An error that occurs during execution (e.g., dividing by zero).
How does a linker work?
It combines compiled code files and libraries into a single executable.

Category 6: Advanced Tools & Concepts

What is a disassembler?
A tool that converts machine code back to assembly language for analysis.
What is static vs. dynamic typing?
- Static typing: Variable types are checked at compile time (e.g., Java).
- Dynamic typing: Types are checked at runtime (e.g., Python).
What is garbage collection?
Automatic memory management in languages like Java/Python to free unused memory.
What is a profiler?
A tool that measures program performance (e.g., CPU/memory usage) to optimize code.

Category 7: Revision Questions

Re-ask: What is the difference between a compiler and an interpreter?
Re-ask: Give two examples of compiled and interpreted languages.
Re-ask: Why might Python be slower than C++?

Category 8: Practical Scenarios

When would you choose a compiled language over an interpreted one?
For performance-critical tasks (e.g., game engines, operating systems).
Why might a beginner prefer an interpreted language like Python?
Easier debugging, no compilation step, and simpler syntax.
What tool would you use to track changes in your code over time?
Version control systems like Git.

7. Revision Questions

What is the role of a compiler?
How does an interpreter work?
What is the purpose of an IDE?