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 is a variable?
A named storage location in computer memory that holds a value.
What is assignment?
Giving a variable a value for the first time.
What is reassignment?
Changing the value of a variable after it has already been assigned.
What are data types?
Categories that classify the type of value a variable can hold.
What is an integer (int)?
A whole number (positive or negative) without a decimal point.
What is a float?
A number with a decimal point.
What is a string (str)?
A sequence of characters enclosed in quotation marks.
What is a boolean (bool)?
A data type representing truth values: True or False.
What is a list?
An ordered collection of items, potentially of different data types, enclosed in square brackets.
What is hand tracing?
Manually stepping through code and keeping track of variable values to understand program execution.