Chapter 4: Control Structures
4.3: Loop Control (break, continue)
When working with loops, there may be situations where you need more control over the execution flow. Sometimes, you may want to terminate the loop prematurely or skip certain iterations of the loop based on certain conditions.
In Python, you can use the break
and continue
statements to modify the behavior of for
and while
loops. The break
statement allows you to terminate the loop prematurely when a certain condition is met. For example, if you are searching for a particular value in a list, you can use the break
statement to terminate the loop as soon as the value is found, instead of continuing to iterate through the rest of the list.
On the other hand, the continue
statement allows you to skip certain iterations of the loop based on a certain condition. For example, if you are iterating through a list of numbers and you only want to process the even numbers, you can use the continue
statement to skip over the odd numbers.
In this topic, we will discuss the use of these loop control statements and how they can be used effectively in different scenarios. By the end of this topic, you should have a better understanding of how to use break
and continue
statements in your Python programs to achieve more precise control over the execution flow of your loops.
4.3.1 break
Statement:
The break
statement is used to exit a loop prematurely, i.e., before the loop's condition becomes false or before iterating over all items in a sequence. When the break
statement is encountered inside a loop, the loop is terminated immediately, and the program continues executing the code following the loop.
For example, let's say we want to search for a specific number in a list and stop the loop once the number is found:
numbers = [1, 2, 3, 4, 5]
search = 3
for number in numbers:
if number == search:
print("Found:", number)
break
Output:
Found: 3
In this example, the loop stops iterating as soon as the search number is found, saving time and resources.
4.3.2 continue
Statement:
The continue
statement is used to skip the rest of the code inside a loop for the current iteration and jump to the next iteration. In other words, when the continue
statement is encountered, Python skips the remaining code in the loop and moves to the next item in the sequence or evaluates the loop condition again.
For example, let's say we want to print all the numbers from 1 to 10, except for the multiples of 3:
for i in range(1, 11):
if i % 3 == 0:
continue
print(i)
Output:
1
2
4
5
7
8
10
In this example, the loop skips printing the numbers that are divisible by 3 and continues with the next iteration.
In summary, loop control statements like break
and continue
can provide significant benefits in terms of control flow within loops. The break
statement, for example, can be used to exit a loop prematurely if certain conditions are met. This can be particularly useful in situations where you want to stop iterating through a loop as soon as a specific condition is met, or if you want to exit the loop altogether.
Similarly, the continue
statement can be used to skip over specific iterations of a loop, which can help to optimize loop performance by avoiding unnecessary computation. By incorporating these control structures into your loops, you can make your code more efficient and readable, while also gaining greater control over the way your programs execute.
Exercise 4.3.1: Print First Five Even Numbers
In this exercise, you will write a Python program that prints the first five even numbers using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Use a
for
loop to iterate through the numbers from 1 to 10 (inclusive). - Use an
if
statement to check if the current number is odd. - If the number is odd, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Print the even number and increment a counter.
- When the counter reaches 5, use the
break
statement to exit the loop.
Your final code should look something like this:
counter = 0
for i in range(1, 11):
if i % 2 != 0:
continue
print(i)
counter += 1
if counter == 5:
break
Output:
2
4
6
8
10
Exercise 4.3.2: Sum of Positive Numbers
In this exercise, you will write a Python program that calculates the sum of all positive numbers in a list using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign a list of integers (positive and negative) to a variable named
numbers
. - Initialize a variable named
total
with the value 0. - Use a
for
loop to iterate through the numbers in the list. - Use an
if
statement to check if the current number is negative. - If the number is negative, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Add the positive number to the
total
variable. - Print the value of
total
after the loop is complete.
Your final code should look something like this:
numbers = [1, -2, 3, -4, 5, -6, 7]
total = 0
for number in numbers:
if number < 0:
continue
total += number
print(total)
Output:
16
Exercise 4.3.3: Find the First Factor
In this exercise, you will write a Python program that finds the first factor of a given number using a for
loop and the break
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign an integer value to a variable named
n
. - Use a
for
loop to iterate through the numbers from 2 ton
(inclusive). - Use an
if
statement to check if the current number is a factor ofn
. - If the number is a factor, print it and use the
break
statement to exit the loop.
Your final code should look something like this:
n = 20
for i in range(2, n + 1):
if n % i == 0:
print("First factor:", i)
break
Output:
First factor: 2
These exercises help you practice using the break
and continue
loop control statements in Python to control the flow of your programs and accomplish various tasks.
4.3: Loop Control (break, continue)
When working with loops, there may be situations where you need more control over the execution flow. Sometimes, you may want to terminate the loop prematurely or skip certain iterations of the loop based on certain conditions.
In Python, you can use the break
and continue
statements to modify the behavior of for
and while
loops. The break
statement allows you to terminate the loop prematurely when a certain condition is met. For example, if you are searching for a particular value in a list, you can use the break
statement to terminate the loop as soon as the value is found, instead of continuing to iterate through the rest of the list.
On the other hand, the continue
statement allows you to skip certain iterations of the loop based on a certain condition. For example, if you are iterating through a list of numbers and you only want to process the even numbers, you can use the continue
statement to skip over the odd numbers.
In this topic, we will discuss the use of these loop control statements and how they can be used effectively in different scenarios. By the end of this topic, you should have a better understanding of how to use break
and continue
statements in your Python programs to achieve more precise control over the execution flow of your loops.
4.3.1 break
Statement:
The break
statement is used to exit a loop prematurely, i.e., before the loop's condition becomes false or before iterating over all items in a sequence. When the break
statement is encountered inside a loop, the loop is terminated immediately, and the program continues executing the code following the loop.
For example, let's say we want to search for a specific number in a list and stop the loop once the number is found:
numbers = [1, 2, 3, 4, 5]
search = 3
for number in numbers:
if number == search:
print("Found:", number)
break
Output:
Found: 3
In this example, the loop stops iterating as soon as the search number is found, saving time and resources.
4.3.2 continue
Statement:
The continue
statement is used to skip the rest of the code inside a loop for the current iteration and jump to the next iteration. In other words, when the continue
statement is encountered, Python skips the remaining code in the loop and moves to the next item in the sequence or evaluates the loop condition again.
For example, let's say we want to print all the numbers from 1 to 10, except for the multiples of 3:
for i in range(1, 11):
if i % 3 == 0:
continue
print(i)
Output:
1
2
4
5
7
8
10
In this example, the loop skips printing the numbers that are divisible by 3 and continues with the next iteration.
In summary, loop control statements like break
and continue
can provide significant benefits in terms of control flow within loops. The break
statement, for example, can be used to exit a loop prematurely if certain conditions are met. This can be particularly useful in situations where you want to stop iterating through a loop as soon as a specific condition is met, or if you want to exit the loop altogether.
Similarly, the continue
statement can be used to skip over specific iterations of a loop, which can help to optimize loop performance by avoiding unnecessary computation. By incorporating these control structures into your loops, you can make your code more efficient and readable, while also gaining greater control over the way your programs execute.
Exercise 4.3.1: Print First Five Even Numbers
In this exercise, you will write a Python program that prints the first five even numbers using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Use a
for
loop to iterate through the numbers from 1 to 10 (inclusive). - Use an
if
statement to check if the current number is odd. - If the number is odd, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Print the even number and increment a counter.
- When the counter reaches 5, use the
break
statement to exit the loop.
Your final code should look something like this:
counter = 0
for i in range(1, 11):
if i % 2 != 0:
continue
print(i)
counter += 1
if counter == 5:
break
Output:
2
4
6
8
10
Exercise 4.3.2: Sum of Positive Numbers
In this exercise, you will write a Python program that calculates the sum of all positive numbers in a list using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign a list of integers (positive and negative) to a variable named
numbers
. - Initialize a variable named
total
with the value 0. - Use a
for
loop to iterate through the numbers in the list. - Use an
if
statement to check if the current number is negative. - If the number is negative, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Add the positive number to the
total
variable. - Print the value of
total
after the loop is complete.
Your final code should look something like this:
numbers = [1, -2, 3, -4, 5, -6, 7]
total = 0
for number in numbers:
if number < 0:
continue
total += number
print(total)
Output:
16
Exercise 4.3.3: Find the First Factor
In this exercise, you will write a Python program that finds the first factor of a given number using a for
loop and the break
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign an integer value to a variable named
n
. - Use a
for
loop to iterate through the numbers from 2 ton
(inclusive). - Use an
if
statement to check if the current number is a factor ofn
. - If the number is a factor, print it and use the
break
statement to exit the loop.
Your final code should look something like this:
n = 20
for i in range(2, n + 1):
if n % i == 0:
print("First factor:", i)
break
Output:
First factor: 2
These exercises help you practice using the break
and continue
loop control statements in Python to control the flow of your programs and accomplish various tasks.
4.3: Loop Control (break, continue)
When working with loops, there may be situations where you need more control over the execution flow. Sometimes, you may want to terminate the loop prematurely or skip certain iterations of the loop based on certain conditions.
In Python, you can use the break
and continue
statements to modify the behavior of for
and while
loops. The break
statement allows you to terminate the loop prematurely when a certain condition is met. For example, if you are searching for a particular value in a list, you can use the break
statement to terminate the loop as soon as the value is found, instead of continuing to iterate through the rest of the list.
On the other hand, the continue
statement allows you to skip certain iterations of the loop based on a certain condition. For example, if you are iterating through a list of numbers and you only want to process the even numbers, you can use the continue
statement to skip over the odd numbers.
In this topic, we will discuss the use of these loop control statements and how they can be used effectively in different scenarios. By the end of this topic, you should have a better understanding of how to use break
and continue
statements in your Python programs to achieve more precise control over the execution flow of your loops.
4.3.1 break
Statement:
The break
statement is used to exit a loop prematurely, i.e., before the loop's condition becomes false or before iterating over all items in a sequence. When the break
statement is encountered inside a loop, the loop is terminated immediately, and the program continues executing the code following the loop.
For example, let's say we want to search for a specific number in a list and stop the loop once the number is found:
numbers = [1, 2, 3, 4, 5]
search = 3
for number in numbers:
if number == search:
print("Found:", number)
break
Output:
Found: 3
In this example, the loop stops iterating as soon as the search number is found, saving time and resources.
4.3.2 continue
Statement:
The continue
statement is used to skip the rest of the code inside a loop for the current iteration and jump to the next iteration. In other words, when the continue
statement is encountered, Python skips the remaining code in the loop and moves to the next item in the sequence or evaluates the loop condition again.
For example, let's say we want to print all the numbers from 1 to 10, except for the multiples of 3:
for i in range(1, 11):
if i % 3 == 0:
continue
print(i)
Output:
1
2
4
5
7
8
10
In this example, the loop skips printing the numbers that are divisible by 3 and continues with the next iteration.
In summary, loop control statements like break
and continue
can provide significant benefits in terms of control flow within loops. The break
statement, for example, can be used to exit a loop prematurely if certain conditions are met. This can be particularly useful in situations where you want to stop iterating through a loop as soon as a specific condition is met, or if you want to exit the loop altogether.
Similarly, the continue
statement can be used to skip over specific iterations of a loop, which can help to optimize loop performance by avoiding unnecessary computation. By incorporating these control structures into your loops, you can make your code more efficient and readable, while also gaining greater control over the way your programs execute.
Exercise 4.3.1: Print First Five Even Numbers
In this exercise, you will write a Python program that prints the first five even numbers using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Use a
for
loop to iterate through the numbers from 1 to 10 (inclusive). - Use an
if
statement to check if the current number is odd. - If the number is odd, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Print the even number and increment a counter.
- When the counter reaches 5, use the
break
statement to exit the loop.
Your final code should look something like this:
counter = 0
for i in range(1, 11):
if i % 2 != 0:
continue
print(i)
counter += 1
if counter == 5:
break
Output:
2
4
6
8
10
Exercise 4.3.2: Sum of Positive Numbers
In this exercise, you will write a Python program that calculates the sum of all positive numbers in a list using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign a list of integers (positive and negative) to a variable named
numbers
. - Initialize a variable named
total
with the value 0. - Use a
for
loop to iterate through the numbers in the list. - Use an
if
statement to check if the current number is negative. - If the number is negative, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Add the positive number to the
total
variable. - Print the value of
total
after the loop is complete.
Your final code should look something like this:
numbers = [1, -2, 3, -4, 5, -6, 7]
total = 0
for number in numbers:
if number < 0:
continue
total += number
print(total)
Output:
16
Exercise 4.3.3: Find the First Factor
In this exercise, you will write a Python program that finds the first factor of a given number using a for
loop and the break
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign an integer value to a variable named
n
. - Use a
for
loop to iterate through the numbers from 2 ton
(inclusive). - Use an
if
statement to check if the current number is a factor ofn
. - If the number is a factor, print it and use the
break
statement to exit the loop.
Your final code should look something like this:
n = 20
for i in range(2, n + 1):
if n % i == 0:
print("First factor:", i)
break
Output:
First factor: 2
These exercises help you practice using the break
and continue
loop control statements in Python to control the flow of your programs and accomplish various tasks.
4.3: Loop Control (break, continue)
When working with loops, there may be situations where you need more control over the execution flow. Sometimes, you may want to terminate the loop prematurely or skip certain iterations of the loop based on certain conditions.
In Python, you can use the break
and continue
statements to modify the behavior of for
and while
loops. The break
statement allows you to terminate the loop prematurely when a certain condition is met. For example, if you are searching for a particular value in a list, you can use the break
statement to terminate the loop as soon as the value is found, instead of continuing to iterate through the rest of the list.
On the other hand, the continue
statement allows you to skip certain iterations of the loop based on a certain condition. For example, if you are iterating through a list of numbers and you only want to process the even numbers, you can use the continue
statement to skip over the odd numbers.
In this topic, we will discuss the use of these loop control statements and how they can be used effectively in different scenarios. By the end of this topic, you should have a better understanding of how to use break
and continue
statements in your Python programs to achieve more precise control over the execution flow of your loops.
4.3.1 break
Statement:
The break
statement is used to exit a loop prematurely, i.e., before the loop's condition becomes false or before iterating over all items in a sequence. When the break
statement is encountered inside a loop, the loop is terminated immediately, and the program continues executing the code following the loop.
For example, let's say we want to search for a specific number in a list and stop the loop once the number is found:
numbers = [1, 2, 3, 4, 5]
search = 3
for number in numbers:
if number == search:
print("Found:", number)
break
Output:
Found: 3
In this example, the loop stops iterating as soon as the search number is found, saving time and resources.
4.3.2 continue
Statement:
The continue
statement is used to skip the rest of the code inside a loop for the current iteration and jump to the next iteration. In other words, when the continue
statement is encountered, Python skips the remaining code in the loop and moves to the next item in the sequence or evaluates the loop condition again.
For example, let's say we want to print all the numbers from 1 to 10, except for the multiples of 3:
for i in range(1, 11):
if i % 3 == 0:
continue
print(i)
Output:
1
2
4
5
7
8
10
In this example, the loop skips printing the numbers that are divisible by 3 and continues with the next iteration.
In summary, loop control statements like break
and continue
can provide significant benefits in terms of control flow within loops. The break
statement, for example, can be used to exit a loop prematurely if certain conditions are met. This can be particularly useful in situations where you want to stop iterating through a loop as soon as a specific condition is met, or if you want to exit the loop altogether.
Similarly, the continue
statement can be used to skip over specific iterations of a loop, which can help to optimize loop performance by avoiding unnecessary computation. By incorporating these control structures into your loops, you can make your code more efficient and readable, while also gaining greater control over the way your programs execute.
Exercise 4.3.1: Print First Five Even Numbers
In this exercise, you will write a Python program that prints the first five even numbers using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Use a
for
loop to iterate through the numbers from 1 to 10 (inclusive). - Use an
if
statement to check if the current number is odd. - If the number is odd, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Print the even number and increment a counter.
- When the counter reaches 5, use the
break
statement to exit the loop.
Your final code should look something like this:
counter = 0
for i in range(1, 11):
if i % 2 != 0:
continue
print(i)
counter += 1
if counter == 5:
break
Output:
2
4
6
8
10
Exercise 4.3.2: Sum of Positive Numbers
In this exercise, you will write a Python program that calculates the sum of all positive numbers in a list using a for
loop and the continue
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign a list of integers (positive and negative) to a variable named
numbers
. - Initialize a variable named
total
with the value 0. - Use a
for
loop to iterate through the numbers in the list. - Use an
if
statement to check if the current number is negative. - If the number is negative, use the
continue
statement to skip the rest of the code in the loop and move on to the next iteration. - Add the positive number to the
total
variable. - Print the value of
total
after the loop is complete.
Your final code should look something like this:
numbers = [1, -2, 3, -4, 5, -6, 7]
total = 0
for number in numbers:
if number < 0:
continue
total += number
print(total)
Output:
16
Exercise 4.3.3: Find the First Factor
In this exercise, you will write a Python program that finds the first factor of a given number using a for
loop and the break
statement.
Instructions:
- Create a new Python file or open a Python interpreter.
- Assign an integer value to a variable named
n
. - Use a
for
loop to iterate through the numbers from 2 ton
(inclusive). - Use an
if
statement to check if the current number is a factor ofn
. - If the number is a factor, print it and use the
break
statement to exit the loop.
Your final code should look something like this:
n = 20
for i in range(2, n + 1):
if n % i == 0:
print("First factor:", i)
break
Output:
First factor: 2
These exercises help you practice using the break
and continue
loop control statements in Python to control the flow of your programs and accomplish various tasks.