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Python Loops
course content

Course Content

Python Loops

Python Loops

1. While Loops: Get Started
Simple While LoopChallenge 1Challenge 2
2. While Loops: Essentials
Infinite LoopsChallengeBreakContinueElseChallenge
3. For Loops
Simple For Loopsrange()enumerate()zip()
4. Nested Loops
Nested LoopsBreak and Continue with Nested LoopsChallenge

bookSimple While Loop

The While statement is one of the basic programming concepts. It repeatedly executes the piece of code.

Imagine you have a task: write the code to calculate the factorial of the given number. For example, for n = 6 the result is: res = 1*2*3*4*5*6 = 720.

The step by step solution is:

Each operation is a new line of code. How many lines are needed? For huge numbers, you'll get very long instructions.

Instead, we'll use the loops. Take a look at how it works:

There are two main parts: stop condition and body. Body are instructions that need to be executed several times. For the factorial task, the body is multiplication the res by the next number. The condition helps to know when to stop.

If a condition is True, the body is executed one more time. When the condition becomes False, the loop is over and we leave it.

In the factorial task, we multiply all numbers from 1 to n so the loop is over when the multiplier becomes greater than n. This way, the stop condition must be False when it happens and True otherwise.

Here is what the syntax looks like in Python:


              
12

            
while condition:
  instructions
copy

Let's code the factorial task in Python. The body instructions are two lines of code:

  • basic operations like multiplying the result by the new number.
  • counter change.

              
1234567

            
n = 6
i = 1 # counter
res = 1 # result variable
while i<=n:
  res *= i
  i += 1
print(i, res)
copy

i is a multiplier which takes all values from 1 to n. It increments by 1 on each iteration. The stop condition is i<=n which is True at the beginning and becomes False when i==n+1. After that, the instructions are over, and the values of i and res are displayed in the console. Now i == n+1.

Task

The task is to find all positive numbers that are multiples of 3 less than 20. We'll do that using loops: starting with num = 0 (0 is a multiple of 3), insert num into the list numbers and then increment the num by 3. Insert the next value and so on until num <= 20.

Output the values in the numbers list.

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Everything was clear?

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Thanks for your feedback!

Section 1. Chapter 1
toggle bottom row

bookSimple While Loop

The While statement is one of the basic programming concepts. It repeatedly executes the piece of code.

Imagine you have a task: write the code to calculate the factorial of the given number. For example, for n = 6 the result is: res = 1*2*3*4*5*6 = 720.

The step by step solution is:

Each operation is a new line of code. How many lines are needed? For huge numbers, you'll get very long instructions.

Instead, we'll use the loops. Take a look at how it works:

There are two main parts: stop condition and body. Body are instructions that need to be executed several times. For the factorial task, the body is multiplication the res by the next number. The condition helps to know when to stop.

If a condition is True, the body is executed one more time. When the condition becomes False, the loop is over and we leave it.

In the factorial task, we multiply all numbers from 1 to n so the loop is over when the multiplier becomes greater than n. This way, the stop condition must be False when it happens and True otherwise.

Here is what the syntax looks like in Python:


              
12

            
while condition:
  instructions
copy

Let's code the factorial task in Python. The body instructions are two lines of code:

  • basic operations like multiplying the result by the new number.
  • counter change.

              
1234567

            
n = 6
i = 1 # counter
res = 1 # result variable
while i<=n:
  res *= i
  i += 1
print(i, res)
copy

i is a multiplier which takes all values from 1 to n. It increments by 1 on each iteration. The stop condition is i<=n which is True at the beginning and becomes False when i==n+1. After that, the instructions are over, and the values of i and res are displayed in the console. Now i == n+1.

Task

The task is to find all positive numbers that are multiples of 3 less than 20. We'll do that using loops: starting with num = 0 (0 is a multiple of 3), insert num into the list numbers and then increment the num by 3. Insert the next value and so on until num <= 20.

Output the values in the numbers list.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 1. Chapter 1
toggle bottom row

bookSimple While Loop

The While statement is one of the basic programming concepts. It repeatedly executes the piece of code.

Imagine you have a task: write the code to calculate the factorial of the given number. For example, for n = 6 the result is: res = 1*2*3*4*5*6 = 720.

The step by step solution is:

Each operation is a new line of code. How many lines are needed? For huge numbers, you'll get very long instructions.

Instead, we'll use the loops. Take a look at how it works:

There are two main parts: stop condition and body. Body are instructions that need to be executed several times. For the factorial task, the body is multiplication the res by the next number. The condition helps to know when to stop.

If a condition is True, the body is executed one more time. When the condition becomes False, the loop is over and we leave it.

In the factorial task, we multiply all numbers from 1 to n so the loop is over when the multiplier becomes greater than n. This way, the stop condition must be False when it happens and True otherwise.

Here is what the syntax looks like in Python:


              
12

            
while condition:
  instructions
copy

Let's code the factorial task in Python. The body instructions are two lines of code:

  • basic operations like multiplying the result by the new number.
  • counter change.

              
1234567

            
n = 6
i = 1 # counter
res = 1 # result variable
while i<=n:
  res *= i
  i += 1
print(i, res)
copy

i is a multiplier which takes all values from 1 to n. It increments by 1 on each iteration. The stop condition is i<=n which is True at the beginning and becomes False when i==n+1. After that, the instructions are over, and the values of i and res are displayed in the console. Now i == n+1.

Task

The task is to find all positive numbers that are multiples of 3 less than 20. We'll do that using loops: starting with num = 0 (0 is a multiple of 3), insert num into the list numbers and then increment the num by 3. Insert the next value and so on until num <= 20.

Output the values in the numbers list.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

The While statement is one of the basic programming concepts. It repeatedly executes the piece of code.

Imagine you have a task: write the code to calculate the factorial of the given number. For example, for n = 6 the result is: res = 1*2*3*4*5*6 = 720.

The step by step solution is:

Each operation is a new line of code. How many lines are needed? For huge numbers, you'll get very long instructions.

Instead, we'll use the loops. Take a look at how it works:

There are two main parts: stop condition and body. Body are instructions that need to be executed several times. For the factorial task, the body is multiplication the res by the next number. The condition helps to know when to stop.

If a condition is True, the body is executed one more time. When the condition becomes False, the loop is over and we leave it.

In the factorial task, we multiply all numbers from 1 to n so the loop is over when the multiplier becomes greater than n. This way, the stop condition must be False when it happens and True otherwise.

Here is what the syntax looks like in Python:


              
12

            
while condition:
  instructions
copy

Let's code the factorial task in Python. The body instructions are two lines of code:

  • basic operations like multiplying the result by the new number.
  • counter change.

              
1234567

            
n = 6
i = 1 # counter
res = 1 # result variable
while i<=n:
  res *= i
  i += 1
print(i, res)
copy

i is a multiplier which takes all values from 1 to n. It increments by 1 on each iteration. The stop condition is i<=n which is True at the beginning and becomes False when i==n+1. After that, the instructions are over, and the values of i and res are displayed in the console. Now i == n+1.

Task

The task is to find all positive numbers that are multiples of 3 less than 20. We'll do that using loops: starting with num = 0 (0 is a multiple of 3), insert num into the list numbers and then increment the num by 3. Insert the next value and so on until num <= 20.

Output the values in the numbers list.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 1. Chapter 1
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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