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Python 3: An interactive deep dive

Numbers

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Numbers are awesome. There are so many to choose from. Python supports both integers and floating point numbers. There’s no type declaration to distinguish them; Python tells them apart by the presence or absence of a decimal point.

Python 3.5
print (type(1))                 #①
#<class 'int'>
print (isinstance(1, int) )     #②
#True
print (1 + 1 )                  #③
#2
print (1 + 1.0 )                #④
#2.0
print (type(2.0))
#<class 'float'>

① You can use the type() function to check the type of any value or variable. As you might expect, 1 is an int.

② Similarly, you can use the isinstance() function to check whether a value or variable is of a given type.

③ Adding an int to an int yields an int.

④ Adding an int to a float yields a float. Python coerces the int into a float to perform the addition, then returns a float as the result.

Coercing Integers To Floats And Vice-Versa

As you just saw, some operators (like addition) will coerce integers to floating point numbers as needed. You can also coerce them by yourself.

Python 3.5
print (float(2) )               #①
#2.0
print (int(2.0))                #②
#2
print (int(2.5) )               #③
#2
print (int(-2.5) )              #④
#-2
print (1.12345678901234567890)  #⑤
#1.1234567890123457
print (type(1000000000000000))  #⑥
#<class 'int'>

① You can explicitly coerce an int to a float by calling the float() function.

② Unsurprisingly, you can ...