6.2. Data Type for True
/False
¶
In order for us to build code that can make decisions, we need to understand how programming languages represent true and false.
Example
If we run the following code, we would see in the following output.
1 2 3 4 | print('dog' == 'cat')
print(3 < 4)
print(3 > 10)
print('dog' != 'cat')
|
Console Output
False
True
False
True
In the code above, we make four comparisons and then print the results to the
console. Python evaluates each comparison as being either True
or
False
.
In line 1, the equality operator
==
compares the strings'dog'
and'cat'
. Since these are NOT the same, the comparison returns the valueFalse
.In line 2, the operator
<
compares the values of 3 and 4. Since 3 is indeed less than 4, comparison returns the resultTrue
.The comparison in line 3 returns
False
, since 3 is NOT larger than 10.In line 4, the
!=
operator stands for “not equal”, so'dog' != 'cat'
returnsTrue
, while something like3 != 3
would returnFalse
.
6.2.1. Identify True
and False
¶
Recall that the type()
function tells us the data type of what’s inside
the ()
.
1 2 3 4 5 | print(3 < 4)
print(type(3 < 4))
print('dog' == 'cat')
print(type('dog' == 'cat'))
|
Console Output
True
<class 'bool'>
False
<class 'bool'>
In the previous chapter, we learned about three data types—int
,
float
, and string
. The first two deal with numbers, while string
deals with collections of characters.
We can now add the data type bool
, which stands for
boolean value, to our list.
6.2.1.1. Boolean Values¶
There are only two boolean values—True
and False
.
Note
Capitalization matters! Since Python is case-sensitive, true
and
false
are NOT valid boolean values.
The values True
and False
are NOT strings. We can see this by printing
another set of type()
results:
Example
1 2 3 | print(type(True))
print(type("True"))
print(True == "True")
|
Console Output
<class 'bool'>
<class 'str'>
False
Putting quotes around boolean values ("True"
and "False"
) makes them
strings, just like "1234"
is a string rather than an int
data type.
Line 3 shows that even though they look similar, True
and "True"
are
NOT the same! str
and bool
are different data types.
6.2.1.2. Data Type Review¶
The string (
str
) data type represents a collection of characters.The integer (
int
) data type represents a whole number.The float (
float
) data type represents a decimal value.The boolean (
bool
) data type representsTrue
orFalse
.