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1 Brave new world

Variables introduction

Data Types in Python

2 A warm welcome

String interpolation

Python naming convention

3  The resistance base

Comments in Python

Python problems practice

4 The mission

If statement

Bool type introduction

5  Back to the streets

Reading From Console in Python

Nested conditionals

6 Who is your friend?

Introduction to for loop

Introduction to a float type

7 The basement

Introduction to while loop

Introduction to functions

8 Reparing Noname

Introduction to lists

Lists - advanced operations

9  Victory is close

Modules

Modulus operation

Python test

10  Wonderland

The day finally came when Noname called me back down to the basement to help him with one of his modules. Finally! One step closer to returning to my own time.

As soon as I keyed in the secret code, I heard his robotic voice. "Hi! Haven't seen you for a while!" Noname said. 
"Hi, Noname," I replied. "Nice to see you too! Let's get started ASAP - I'm eager to return to my time! 
"Let's start with my antivirus protection system," Noname suggested. 
"What should I do?"

"My problem isn't with the antivirus detection itself, but with running the scan. As you know, Ritchie did everything he could to control me. Part of that was adding remote access to my system so that he could connect to and check what I was doing. An antivirus check is forbidden for me - if he sees me checking for viruses, he'll immediately shut me down. I need help with scanning my files quickly and then being able to stop scanning as soon as Ritchie connects."

I took a few seconds to consider the problem. "If I know the number of files to scan," I thought out loud, "I can write a 

 loop to iterate through all of the files to scan them," I suggested. 
"And how will the scan stop if Ritchie connects to the system?" 
"I haven't thought that far ahead yet," I admitted. "Do 

 have anything in mind?" 
"Well, if you're open to learning, I can teach you how to use a 

 loop," Noname replied. 
"Sounds good," I said. "Enlighten me!"

"Okay, my dear human, listen up. Some programmers refer to the for loop as a '

'. That's because a for loop is typically pre-programmed to run a specific number of times; like 5, 10, etc. In contrast, a 

"loop with an unknown number of repetitions"

because you don't know exactly how many times it will iterate. Here is a 

loop executes a code in its body while a specified condition is

This diagram illustrates the basics of a 

"See those examples I just showed you?" Noname asked. "The first two examples are trivial. But the last one is interesting. Do you understand what  it is doing?" 
"Let's see. It looks like it asks the user if they want one more candy. As long as the user enters 'Yes,' it increments the candy count. As soon as the user answers anything but 'Yes,' it stops the loop." 
"Correct! You're a quick learner, Teo. Now let's get you writing your first 

"Same as with the for loop, you should use indentation, to show Python which parts of your program are inside the loop, and which ones are outside," Noname added.

 loop, and vice-versa. In the below example, the code snippets in the left and right columns of the following table are equivalent:

"Now that you have some practice with these loops, try to stick to this rule: 

if you know beforehand how many times your code will be executed, consider using a

"And now," Noname continued, "to make your loop knowledge complete, I want to tell you about 

 can be applied to the loop that is inside another loop. Take a look at this example: 

"What is this doing again?" I asked pointing at the '

"You should use this construction, to instruct print to NOT go to a new line after it outputs the text to the console. See here:"

"What do you think about it?" Noname asked. 
"This opens up such a wide field of opportunities!" I exclaimed. 
Noname replied, "Right, Teo, totally agree! One more useful feature is that you can use the outer loop variable in the inner loop. This means that the inner loop can "know" which iteration is currently in the outer loop. Here is a small demonstration: 

"Noname, I think that's enough of theory for today," I said. 
"Are you tired? Don't worry, the human brain absorbs information much more slowly than machine memory. Understanding will come, maybe after some tasks!"

"I believe you are ready to fix my antivirus system!" Noname said once I had completed his tasks. 

Unlock the fundamentals of iterative programming with our guide to while loops in Python. Learn to create efficient loops for repetitive tasks and control flow in your code at CodeEasy.io.

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