Python Programming for Raspberry Pi, Sams Teach Yourself in 24 Hours

The int function will convert a number from a string data type to an integer data type. You can use
the float function to convert a number from a string to a floating-point data type. Listing 4.26 shows
how to convert the variable cups_consumed to an integer data type.

LISTING 4.26 Data Type Conversion via the int Function

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>>> cups_consumed = input ("How many cups did you drink? ")

How many cups did you drink? 3

>>> type (cups_consumed)

<class 'str'>

>>> cups_consumed = int(cups_consumed)

>>> type (cups_consumed)

<class 'int'>

>>>

You can get really tricky here and use a nested function. Nested functions are functions within
functions. The general format, is as follows:

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variable = functionA(functionB(user_prompt))

Listing 4.27 uses this method to properly change the input data type from a string to an integer.

LISTING 4.27 Using Nested Functions with input

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>>> cups_consumed = int(input("How many cups did you drink? "))

How many cups did you drink? 3

>>> type (cups_consumed)

<class 'int'>

>>>

Using nested functions makes a Python script more concise. However, the trade-off is that the script is
a little harder to read.

Try It Yourself: Explore Python Input and Output with Variables

You are now going to explore Python input and output using variables. In the following

steps, you will write a script to play with, instead of using the interactive Python shell:

1. If you have not already done so, power up your Raspberry Pi and log in to the
   system.


2. If you do not have the LXDE GUI started automatically at boot, start it now by typing
   startx and pressing Enter.


3. Open the LXTerminal by double-clicking the LXTerminal icon.


4. At the command-line prompt, type nano py3prog/script0402.py and press
   Enter. The command puts you into the nano text editor and creates the file