How To Convert Strings to Integers in Python 3

Strings can be converted to integers by using the int() method.

If your string does not have decimal places, you’ll most likely want to convert it to an integer by using the int() method.

Let’s use an example of the user sammy keeping track of lines of code written each day. We may want to manipulate those values with math to provide more interesting feedback for the user, but those values are currently stored in strings:

lines_yesterday = "50" lines_today = "108"  lines_more = lines_today - lines_yesterday  print(lines_more) 
OutputTypeError: unsupported operand type(s) for -: 'str' and 'str' 

Because the two numeric values were stored in strings, we received an error. The operand - for subtraction is not a valid operand for two string values.

Let’s modify the code to include the int() method that will convert the strings to integers, and allow us to do math with these values that were originally strings.

lines_yesterday = "50" lines_today = "108"  lines_more = int(lines_today) - int(lines_yesterday)  print(lines_more) 

The variable lines_more is automatically an integer, and it is equal to the numeric value of 58 in this example.

If you want to learn more about converting Python data types, check out How To Convert Data Types in Python 3 as well as our How To Code in Python 3 series.