> For the complete documentation index, see [llms.txt](https://memoryerror.gitbook.io/python-basics/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://memoryerror.gitbook.io/python-basics/print-function-variables-and-development-environment.md).

# Print function, strings, variables and development environment

Welcome back to the Python basics tutorial! Today I'm gonna teach how to set up a development environment for Python *and* more on the mysterious print function.\
\
Till now, you've been entering a line at a time in the python prompt. But what if you make a mistake somewhere in the program? Then you'll have to start over again. But if you save it to a file, you can just edit the program if you have any mistakes. Now, you *can not* use any text editor for editing Python code. Sorry buddy, no MS Word this time.\
\
So you need an IDE (Integrated Development Environment) or a Text Editor.  They have some useful features, such as identifying errors and bad practices when coding and much more. As you're still a beginner, you'll not need them. They might just end up confusing you with all the setup. Your main focus will be writing code.

{% hint style="info" %}
Some good IDE's are PyCharm, Visual Studio Code, and Eclipse (with PyDev plugin). Some good text editors are Atom, Sublime Text, PyPad and Vim.
{% endhint %}

 On Windows, you should have a program called IDLE (Integrated DeveLopment Environment) installed by default with Python. In Mac, you can fire up TextEdit and in Linux you should have a program called Text Editor installed as well.

 Or if you want to install IDLE, you can use `brew` in Mac and your Linux distro's package manager to install the package `idle` . IDLE is almost perfect for a beginner who doesn't need advanced features right away.

{% hint style="info" %}
You should type the code in the tutorials instead of copy-pasting since it helps with learning.
{% endhint %}

Now, open IDLE and type the same line of code:

```python
print('Hello World')
```

in the blank field.

{% hint style="info" %}
The colored text is called "Syntax Highlighting".
{% endhint %}

Now use CTRL + S for PC and CMD + S for Mac and save the file as hello.py \
We use the `.py` extension to indicate that this is a Python program.

Now that you've saved the file, press F5 to run the program. You'll see a new window open up with the Python prompt and you'll see "Hello World" displayed again. Now go back to the editor and type in:

```python
print('Hello, World!')
print('This is another one!')
print('This too!')
```

and run. Now you should see the text being printed to the screen.

Great! Now you have a development environment where you can save your programs and more!

{% hint style="info" %}
There's a free web service called <https://repl.it> where you can run Python code in your browser directly without having to install Python. However, it is not recommended for actual projects.
{% endhint %}

## Alright, I've learned all about development environments.

Good. Now we can get to learning about the `print` function. First of all, what are functions? Functions are "blocks" or pieces of code that are run when "called". You can pass data to them too. A function is usually called like this:<br>

```python
function_name(data1, data2)
```

{% hint style="info" %}
You'll learn about functions in another chapter.
{% endhint %}

`print` is also a function. When you call `print` like `print('Hello World')` it prints the text given inside the quotes. You can add more text like this:<br>

```python
print('This is some text', 'and this is more')
```

## Strings

It's an odd name, right? What do strings have to do with programming? Well, here a "string" is a string of characters. So, strings in programming are actually just text data. To make a string in Python, you need to enclose it in quotes, like:

```python
'Python is awesome'
```

or double quotes:<br>

```python
"Python is awesome, even with double quotes!"
```

But you cannot start with a single quote and end with a double or vice versa:

```python
"Python will not allow you to do this.'
```

This will result in a `SyntaxError` which means your code has mistakes such as a missing quote or bracket.

The text you pass to `print` is also a string.

Adding two strings together is called concatenation. You do it like this:

```python
'This is a bit of text ' + 'added with some more!'
```

To print it out:

```python
print('String 1' + 'String 2')
```

which results in "String 1String 2"

{% hint style="info" %}
What if you had to put a quote in a string like 'I don't think I can'? It would make Python think that you're ending the string at `don` . To prevent that, you have to "escape" the quote with a backlash like 'I don\\'t think I can'.
{% endhint %}

Now, if you had two print "Hello World" three times:

```python
print('Hello World')
print('Hello World')
print('Hello World')
```

No big deal, right? But what if you had a larger string? That would be a pain to type out. So, what do you do? Here's where variables come in.

## Variables

So, you have a really long string you want to print three times. To avoid typing it out every time, you can assign it to a variable. Let's say we want to assign "This is a really really long string to type out" to `x` just like we did in algebra. But this time, with strings. So, we assign it like this:

```python
x = 'This is a really really long string to type out'
```

Now, instead of the string, you can just use `x` to refer to it. So, this should work:

```python
x = 'This is a really really long string to type out'
print('x')
```

Run the code. Does it work? Nope. It just prints 'x'. This is because you are creating a whole new string. Variables are used just like how they were assigned, without quotes.

```python
x = 'This is a really really long string to type out'
print(x)
```

Does it work now? Yes it does!\
Remember, a variable can only start with a letter. The variable name can not start with a number or a symbol. It can not have a symbol within either. It cannot have spaces.\
Correct variable names: `memory_error123`, `python_is_cool`

Incorrect variable names: `123harry_potter`, `this$is$really$wrong`

Variable names should always be all-lowercase and words should be separated with underscores.\
Good - `days_of_week`\
Bad - `dAYsOFtHEWeEk`&#x20;

You can add more variables and print them too!

```python
name = 'John'
address = '445 Mount Eden Road, Mount Eden, Auckland'
print(name, address) 
```

That's a lot you've learned today. Some important points to remember:<br>

* Strings are created with quotes, single or double.
* Variables are refered to normally without quotes.
* `SyntaxError` is shown when you have a mistake in your code

You're good to go!

## Homework

Your homework will be trying to add words as strings together and make a sentence.

Next chapter we're going to learn more about other data types.