Chapter 3: Control Structures: Conditionals and Loops

 

3.1 Conditional
Statements 3.1.1 if statement and its syntax Explanation: The if statement
allows you to execute a block of code based on a certain condition. Example:

python

///Example

num = 10

if num > 0:

    print("The number is positive.")

 

3.1.2 else and elif
statements Explanation: The else statement provides an alternative block of
code to execute when the condition in the if statement is False. The elif
statement allows you to check multiple conditions. Example:

python

///Example

num = 0

if num > 0:

    print("The number is positive.")

elif num < 0:

    print("The number is negative.")

else:

    print("The number is zero.")

 

3.2 Looping Constructs:
for and while Loops 3.2.1 The for loop: iterating over sequences, lists, and
ranges Explanation: The for loop allows you to iterate over a sequence or a
range of values, executing a block of code for each iteration. Example:

python

///Example

fruits =
["apple", "banana", "orange"]

for fruit in fruits:

    print(fruit)

 

3.2.2 The while loop:
loop continuation conditions and control flow Explanation: The while loop
executes a block of code repeatedly as long as a certain condition is True.
Example:

python

///Example

count = 0

while count < 5:

    print("Count:", count)

    count += 1

 

3.3 Loop Control
Statements 3.3.1 Using the break statement to exit loops prematurely
Explanation: The break statement allows you to exit a loop prematurely,
skipping the remaining iterations. Example:

python

///Example

fruits =
["apple", "banana", "orange"]

for fruit in fruits:

    if fruit == "banana":

        break

    print(fruit)

 

3.3.2 Using the
continue statement to skip iterations Explanation: The continue statement
allows you to skip the current iteration of a loop and move on to the next
iteration. Example:

python

///Example

numbers = [1, 2, 3, 4,
5]

for number in numbers:

    if number % 2 == 0:

        continue

    print(number)

 

3.4 Exception Handling
with try and except 3.4.1 Understanding exceptions and error handling
Explanation: Exceptions are events that occur during the execution of a program
that disrupt the normal flow of the program. Error handling allows you to catch
and handle these exceptions gracefully. Example:

python

///Example

try:

    x = 10 / 0

except ZeroDivisionError:

    print("Error: Cannot divide by
zero.")

 

3.4.2 Handling specific
exceptions and multiple exceptions Explanation: You can handle specific
exceptions by specifying the exception type. Multiple exceptions can be handled
using multiple except blocks. Example:

python

///Example

try:

    num = int(input("Enter a number:
"))

    result = 10 / num

except ValueError:

    print("Error: Invalid input. Please
enter a valid number.")

except
ZeroDivisionError:

    print("Error: Cannot divide by
zero.")

 

This chapter covers the
fundamentals of control structures, including conditional statements and
looping constructs. It also introduces exception handling for handling errors
and unexpected situations. The examples provided demonstrate the usage and
syntax of each topic, helping readers understand how to apply these concepts in
their own programs.