How do I write code of more than 1 line in the Python interpreter?

Question

I have a problem coding Python in terminal. I'm just learning basics so I have no need to create .py files.

In terminal I can run one line of code in the Python interpreter, but how do I write more than one line?

Obviously if I hit enter, it enters the command and doesn't go down a line.

I just want to test following in terminal:

my_age = 35
my_eyes = 'Blue'
print "my age is %d and my eye color is %s" % (my_age, my_eyes)

Answer 1

The trick is – similar to what you would do in bash, for example – to add a trailing backslash.

Example:

charon:~ werner$ python
>>> print 1
1
>>> print \
... 1
1
>>> 

If you write a \, it will prompt you with ... to enter code in the next line, so to say. This is however what automatically happens when you create a function or class definition, i.e. the tiems when you really need a new line, so there's never a really good use for that, or at least none that I know of.

---

For everything else, you need to write one line after another. The way an interpreter works is that it, well, interprets every line that you feed it. Not more, not less. It will only "act" when it sees a newline, therefore telling the interpreter to execute what you gave it. The single backslash will prevent the interpreter from ever receiving a newline character (i.e. it won't know that you actually pressed Enter), but it will eventually receive one.

Python's interpreter has advanced capabilities when you use GNU readline, such as Emacs or vi-style keybindings to navigate within a line (e.g. Ctrl-A). Those however work only in the one current line. History is there as well, just try and press ↑.

But, apart from that, you probably want to use proper source files if you want to execute more than one line of code at a time.

Answer 2

Simply put, if you want to learn and want to run more than one line you write it into a .py file.

The trailing backslash method is good when you quickly want to run a series of commands, but it doesn't help when you are learning.

You will be able to develop code better, edit individual commands without worrying about spelling mistakes, and reuse code snippets you find useful if you write them into a small file.