Lesson 01-05: Conversion Functions¶

Learning Target: I can convert datatypes from one type to another.

At times, you will be given datatype in one form, but you’ll want to use it in another. For example, later on you’ll be learning how to use the input() function to get the user to type something in, and that always gives you data as a string. But what if you wanted the user to type in a number? How would you change that string to a number?

The Conversion Functions¶

You would use conversion functions, which are functions that turn one datatype into another datatype.

Table of the conversion functions:

To convert to a String, use... str()

To convert to a Boolean, use... bool()

To convert to a Float, use... float()

To convert to an Integer, use... int()

You would use these functions by putting the value you want to convert between the parentheses. Try running the example below:

Here are a few notes for specific type to type conversions:

From To Resulting Effect

any string put quotes around the value

int float put a .0 at the end

float int drop everything after decimal point

string int becomes an int if it looks like a number

string float becomes a float if it looks like a number

From	To	Resulting Effect
any	string	put quotes around the value
int	float	put a .0 at the end
float	int	drop everything after decimal point
string	int	becomes an int if it looks like a number
string	float	becomes a float if it looks like a number

Checks for Understanding¶

Q#1¶

float("10")

(A) int
Which conversion function is being used?
(B) float
Nice job!
(C) string
Which conversion function is being used?

Q#2¶

str(False)

(A) int
Which conversion function is being used?
(B) float
Which conversion function is being used?
(C) string
Nice job!

Q#3¶

str(2.3)

(A) 2
What's the rule when the str() function is used?
(B) "2.3"
Nice job!
(C) 2.3
What's the rule when the str() function is used?
(D) "2"
What's the rule when the str() function is used?

The `type()` Function¶

There is a function, type(), that will tell you the datatype of a value. Run the following code as an example:

This is useful for debugging purposes if you ever need to see the type of a value.

A Note on Errors¶

So what happens if you try to convert something like a word to an integer? See for yourself:

Note the error. Keep that in mind! Only strings that use digits can be converted to numbers.

Next Section - Lesson 01-06: Introduction to Variables

To convert to a String, use...	`str()`
To convert to a Boolean, use...	`bool()`
To convert to a Float, use...	`float()`
To convert to an Integer, use...	`int()`