Programming Fundamentals Flashcards

Question 1

What is a variable in a programming language?

Accepted Answer

A variable is a named storage location that holds a value which a program can read and change. The name lets you refer to the value later. Assigning a new value replaces the old one, so the same name can hold different data at different times.

Question 2

What does the assignment operator do in most languages?

Accepted Answer

The assignment operator stores the value on its right side into the variable named on its left side. In many languages it is written as a single equals sign, which is different from a comparison that tests whether two values are equal.

Question 3

What is the difference between an integer and a floating-point number?

Accepted Answer

An integer is a whole number with no fractional part, such as 7 or negative 3. A floating-point number stores values with a decimal point, such as 3.14, and it can only approximate many real numbers. Because of this approximation, comparing two floating-point results for exact equality can give surprising answers.

Question 4

What is a string and how is it typically used?

Accepted Answer

A string is a sequence of characters, such as letters, digits, and punctuation, stored as a single value. Programs use strings for text like names, messages, and file paths. Many languages let you join strings together, search them, or extract parts of them using built-in operations.

Question 5

What is a boolean value and where is it used?

Accepted Answer

A boolean value is either true or false, and it represents the result of a yes or no test. Conditions in if statements, loops, and filters rely on boolean results to decide which path a program takes. Many languages treat some other values as true or false, so checking the language rules matters.

Question 6

What is type conversion, and why does it matter?

Accepted Answer

Type conversion changes a value from one data type to another, such as turning text 42 into a number. Mixing types without care can cause errors or surprising results. Explicit conversion makes the intent clear to anyone reading the code and helps prevent bugs.

Question 7

What is a constant, and how does it differ from a variable?

Accepted Answer

A constant is a named value that is set once and cannot be changed while the program runs. Many languages enforce this protection, which makes code easier to read and safer to maintain. Values like the number of days in a week are good candidates for constants.

Question 8

Why do programmers choose meaningful variable names?

Accepted Answer

Meaningful variable names describe what a value represents, so the code explains itself to readers. A name like total_price is far easier to understand than a vague name like x or tmp. Clear naming reduces the need for comments and helps teammates and your future self follow the logic quickly.

Question 9

What is control flow in a computer program?

Accepted Answer

Control flow is the order in which a program executes its instructions. By default, statements run one after another from top to bottom. Control structures such as conditionals and loops change that order, letting a program make decisions and repeat work.

Question 10

What does an if statement do when a program runs?

Accepted Answer

An if statement runs a block of code only when a specified condition evaluates to true. If the condition is false, the program skips that block and continues with the code after it. Many languages also allow an else block, which runs when the condition is false.

Question 11

How does an else if branch differ from a separate if statement?

Accepted Answer

An else if branch is checked only when earlier conditions are false, so just one branch in a chain runs. Separate if statements are each checked on their own, so several can run for the same input. Choosing the right form prevents logic errors when outcomes should be mutually exclusive.

Question 12

What is a loop, and why do programs use them?

Accepted Answer

A loop repeats a block of code while a condition remains true or for each item in a collection. Programs use loops to perform the same task many times without copying the code, which keeps programs shorter and easier to change. Processing every record in a list is a typical example.

Question 13

What is the difference between a while loop and a for loop?

Accepted Answer

A while loop repeats as long as its condition stays true, even if the total count is unknown. A for loop suits cases where the number of repetitions is known or where each item in a sequence is processed. Both can often solve the same problem, so the choice is mostly about clarity.

Question 14

What do break and continue statements do inside a loop?

Accepted Answer

A break statement exits the loop immediately, and execution continues with the code after the loop. A continue statement skips the rest of the current iteration and moves on to the next one. Both help handle special cases without deeply nesting extra conditionals.

Question 15

What is an infinite loop and how can it occur?

Accepted Answer

An infinite loop is a loop whose exit condition never becomes false, so it keeps running until the program is stopped. It often happens when a loop variable never changes, so the stopping test is never reached. Checking that each loop makes progress toward its exit condition prevents this problem.

Question 16

Why is it useful to trace code by hand with a simple example?

Accepted Answer

Tracing code by hand means following each line with sample values and writing down the state after every step. It reveals whether the control flow matches what you intended, especially at branch boundaries and loop endings. The habit builds an accurate mental model before you run anything.

Question 17

What is a function in programming and why use one?

Accepted Answer

A function is a named, reusable block of code that performs a specific task and may return a result. Functions accept inputs called parameters, and the values passed in are called arguments. Breaking a program into functions makes each piece easier to test, understand, and reuse.

Question 18

What is the difference between a parameter and an argument?

Accepted Answer

A parameter is the variable named in a function definition, while an argument is the actual value supplied when the function is called. For example, in a function defined as add(a, b), the names a and b are parameters. A call such as add(2, 3) supplies the arguments 2 and 3.

Question 19

What does a return value represent in a function?

Accepted Answer

A return value is the result a function sends back to the code that called it. A function that returns a value can be used in expressions, stored in variables, or passed to other functions. A function without a return value typically performs an action, such as printing text or updating a file.

Question 20

What does local scope mean for a variable inside a function?

Accepted Answer

Local scope means a variable is visible only within the block or function where it was declared. Once that block finishes, the variable is no longer accessible from outside. Local scope keeps helper values from interfering with other parts of a program, which reduces accidental bugs.

Question 21

What is global scope, and why can it cause problems?

Accepted Answer

A global variable is declared outside any function and can be changed from many parts of a program. Because any code can modify it, tracking down where a value changed can become difficult as a program grows. Relying on shared state makes functions harder to test, so minimizing globals is a common practice.

Question 22

What characteristics make a function a pure function?

Accepted Answer

A pure function always returns the same output for the same inputs and does not change anything outside itself. It does not read or write global state, files, or the user's screen. Pure functions are easier to test and reason about, which is why many programmers prefer them when possible.

Question 23

Why do functions help avoid repeating code?

Accepted Answer

A function lets you write logic once and call it from many places, so one fix applies everywhere. This principle is often called not repeating yourself, which reduces the chance that copies drift apart. Shorter, focused functions also make the overall structure of a program easier to read.

Question 24

What is recursion, and what must a recursive function include?

Accepted Answer

Recursion is when a function calls itself to solve a smaller version of the same problem. A recursive function must include a base case that stops the calls, otherwise it can run out of memory. Calculating a factorial is a classic example.

Question 25

What is an array, and how are its elements accessed?

Accepted Answer

An array is an ordered collection of values stored in contiguous positions and identified by an index. Most languages number indexes starting at zero, so the first element sits at index 0. Accessing an element by its index is typically very fast, regardless of how large the array is.

Question 26

What is a linked list, and how does it differ from an array?

Accepted Answer

A linked list stores items as nodes, each holding a value and a reference to the next node. Unlike an array, its items are not stored in one continuous block, so reaching a position requires following links. Linked lists make insertion and removal cheap once a node is known, but random access is slower.

Question 27

What is a stack, and what is the order of removal?

Accepted Answer

A stack is a collection that adds and removes items at one end only, following last in, first out order. The most recently added item is always the first one removed. Stacks are used for tasks such as tracking function calls, undoing actions, and checking balanced brackets.

Question 28

What is a queue, and how does it differ from a stack?

Accepted Answer

A queue is a collection where items are removed in the same order they were added, following first in, first out. A stack removes the most recently added item first, so the two structures produce opposite removal orders. Queues are common for scheduling jobs, handling requests in arrival order, and managing print tasks.

Question 29

What is a dictionary, also called a hash map or associative array?

Accepted Answer

A dictionary stores pairs of keys and values, letting you look up a value by its key rather than by a numeric position. Keys must be unique, so assigning a value to an existing key replaces the old one. Dictionaries are useful for counting items, mapping names to records, and caching results.

Question 30

Why is searching a sorted array often faster than searching an unsorted one?

Accepted Answer

Sorted order lets a search rule out large portions of the data at each step, as binary search does. Binary search checks the middle element and discards the half that cannot hold the target, needing about log base two of n steps. An unsorted array may require checking every element one by one.

Question 31

What is Big O notation used for?

Accepted Answer

Big O notation describes how the time or memory an algorithm needs grows as its input size grows. It ignores constant factors and lower-order terms, so it captures the overall growth pattern rather than exact timings. Common examples include constant, linear, and quadratic growth.

Question 32

Why should you choose a data structure based on the operations you need?

Accepted Answer

Each data structure makes some operations fast and others slow, so the right choice depends on what the program does most often. For example, an array suits fast indexed reads, while a dictionary suits fast lookups by key. Matching the structure to the typical workload is a core skill in programming.

Question 33

What is a bug, and how does it differ from a syntax error?

Accepted Answer

A bug is any flaw in a program that causes it to behave differently from what was intended. A syntax error is a violation of the language's grammar rules, which usually stops the program from running at all. A logic bug, by contrast, often lets the program run while producing wrong results.

Question 34

What is a runtime error, and when does it appear?

Accepted Answer

A runtime error is a problem that occurs while a program executes, such as dividing by zero. The program may crash or stop at the point where the error occurs. Such errors often depend on input or environment, so they may appear only in some situations.

Question 35

What is a breakpoint, and how does it help with debugging?

Accepted Answer

A breakpoint is a marker set on a line of code that pauses execution when the program reaches that line. While paused, you can inspect variable values and step through the following lines one at a time. This shows what the program is doing, which is often faster than adding print statements everywhere.

Question 36

What is a systematic way to debug a problem?

Accepted Answer

Start by reproducing the problem reliably, then narrow down where the behavior first goes wrong. Form a specific hypothesis about the cause, test it with a small change or check, and observe the result. Repeat this cycle until you understand the cause, then fix it and confirm the fix.

Question 37

Why is a version control system valuable for a programmer?

Accepted Answer

A version control system records the history of changes to your code so you can see what changed and why. It lets you return to an earlier working version if a new change breaks something. It also makes it easier for several people to work on the same project without overwriting each other's edits.

Question 38

What is the purpose of a comment in source code?

Accepted Answer

A comment is a note written in the source code that the computer ignores when running the program. Comments explain why the code does something, which is more useful than repeating what the code plainly states. Good comments help future readers, including your future self, understand intent and assumptions.

Question 39

Why is testing code with small inputs and edge cases important?

Accepted Answer

Small inputs make it easy to predict the correct output by hand, so mismatches are quick to spot. Edge cases such as empty lists, zero, negative numbers, and the largest values often expose mistakes that typical inputs hide. Writing small tests for these cases also protects against regressions when the code changes later.

Question 40

What does it mean to write readable code, and why does it matter?

Accepted Answer

Readable code is organized and named so that another person can understand its purpose and behavior without much effort. It matters because programs are read far more often than they are written, and unclear code slows down debugging and changes. Consistent formatting, sensible names, and small focused functions are common ways to improve readability.

Programming Fundamentals Flashcards

1Variables and Data Types

2Control Flow

3Functions and Scope

4Data Structures

5Debugging and Good Practice

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