Converting Variable Types
How can we convert from one variable type to another?
In Python, you can convert from one variable type to another using type casting. Type casting is the process of changing the data type of a variable from one type to another. This may be useful if you are trying to manipulate or extract more specific information from a variable. Here are some ways to perform type casting in Python.
To convert a variable to an integer, you can use the int() function. Note that this will always round the value down if it is passed in as a float. For example:
x = 3.14
y = int(x) # y will be 3
cost = 19.99
newCost = int(cost) # this will round the value down to 19
ageString = "27"
ageInt = int(ageString) # will return just 27, without the quotations
To convert a variable to a float, you can use the float() function. For example:
x = 42
y = float(x) # y will be 42.0
To convert a variable to a string, you can use the str() function. For example:
pi = 3.14159
x = str(pi) # x will be "3.14159"
To convert a variable to a boolean, you can use the bool() function. Note that if the numeric value 0 is passed into bool() function, it will return False, while everything returns True. This may not sound like a very intuitive function to use, but there may be given instances that we see later on where this may helpful. For example:
a = 0
b = bool(a) # b will be False
c = 25
d = bool(c) # c will be True (non-zero)
e = "Hello World"
f = bool(f) # f will be True (non-zero)
Note that not all conversions are possible or meaningful. For example, converting a string that contains non-numeric characters to an integer or a float will result in a ValueError. For example:
name = "John"
x = int(name) # results in a ValueError because name contains characters
At any given time, you can check the type of a variable by simply using the type() function and passing the variable inside the parentheses:
name = "John"
age = 45
wage = 18.75
print(type(name)) # str
print(type(age)) # int
print(type(wage)) # float
It’s important to be aware of the data types of your variables and to use type casting carefully to avoid errors and unexpected behavior in your code.