All Flashcards
What is the purpose of variables in programming?
To store and manipulate data within a program.
Why are data types important?
They determine what operations can be performed on the data and ensure data integrity.
Explain the concept of mutability in the context of variables.
Mutability refers to whether the value of a variable can be changed after it's been assigned. Some data types (like lists) are mutable, while others (like strings in some languages) are not.
Describe the difference between a statically-typed and dynamically-typed language.
In statically-typed languages, the data type of a variable is checked at compile time. In dynamically-typed languages, the data type is checked at runtime.
Explain how variable scope affects program behavior.
Variable scope determines where in the program a variable can be accessed. Variables declared within a function typically have local scope.
Why is it important to choose the correct data type for a variable?
Using the correct data type ensures efficient memory usage, prevents errors, and allows appropriate operations to be performed.
What is the significance of using meaningful variable names?
Meaningful variable names improve code readability and make it easier to understand the purpose of each variable.
Explain the concept of type casting or type conversion.
Type casting is converting a variable from one data type to another (e.g., from an integer to a string).
What are the potential consequences of using the wrong data type?
It can lead to unexpected behavior, errors, incorrect calculations, and inefficient memory usage.
Explain the difference between local and global variables.
Local variables are defined within a specific scope (e.g., inside a function) and are only accessible within that scope. Global variables are defined outside any function and are accessible throughout the program.
What does the following code output?
python
x = 10
y = x + 5
x = 20
print(y)```
15
What does the following code output?
python
name = "Alice"
age = 30
print("Hello, " + name + ". You are " + str(age) + " years old.")```
Hello, Alice. You are 30 years old.
What does the following code output?
python
x = True
y = False
print(x and y)```
False
What does the following code output?
python
numbers = [1, 2, 3, 4, 5]
print(numbers[2])```
3
What does the following code output?
python
x = 5
if x > 0:
print("Positive")
else:
print("Non-positive")```
Positive
Identify the error in the following code:
python
pi = 3.14
print("The value of pi is: " + pi)```
TypeError: can only concatenate str (not "float") to str. The float variable pi needs to be converted to a string using str(pi) before concatenation.
Identify the error in the following code:
python
count = 5
if Count > 0:
print("Valid")```
NameError: name 'Count' is not defined. Variable names are case-sensitive; 'Count' is different from 'count'.
What does the following code output?
python
my_list = [10, 20, 30]
my_list[1] = 25
print(my_list)```
[10, 25, 30]
What does the following code output?
python
x = 7
x = x * 2 + 1
print(x)```
15
What does the following code output?
python
flag = False
if not flag:
print("Flag is False")```
Flag is False
What are the differences between integers and floats?
Integers: Whole numbers | Floats: Numbers with decimal points.
What are the differences between strings and lists?
Strings: Immutable sequences of characters | Lists: Mutable ordered collections of items.
What are the differences between assignment and reassignment?
Assignment: Giving a variable a value for the first time | Reassignment: Changing the value of an existing variable.
What are the differences between local and global variables?
Local: Accessible only within the function/block where defined | Global: Accessible throughout the entire program.
What are the differences between True and False in boolean context?
True: Represents a condition that is met or satisfied | False: Represents a condition that is not met or not satisfied.
What are the differences between single quotes and double quotes for strings in Python?
Single quotes: Used to define simple strings | Double quotes: Also used to define strings, allow embedding single quotes without escaping.
What are the differences between mutable and immutable data types?
Mutable: Can be changed after creation (e.g., lists) | Immutable: Cannot be changed after creation (e.g., strings, tuples).
What are the differences between == and is operators in Python?
==: Checks if the values are equal | is: Checks if the objects are the same (same memory location).
What are the differences between explicit and implicit type conversion?
Explicit: Manually converting a data type using functions like int(), str() | Implicit: Automatic conversion performed by the interpreter.
What are the differences between an empty string and a None value?
Empty string: A string with zero characters ("") | None: Represents the absence of a value or a null value.