How to Convert Strings into Integers in Python

title: How to Convert Strings into Integers in Python

How to Convert Strings into Integers in Python

Just like the str() built-in, Python also offers a handy built-in which takes a string object as an argument and returns the corresponding integer object.

Example Usage:

# Here age is a string object
age = "18"
print(age)
# Converting string to integer
int_age = int(age)
print(int_age)

Output

18
18

Here although the output is visually similar but you should keep in mind that the first line prints a string object while the line next to it prints a integer object which is further illustrated in the next example:

age = "18"
print(age+2)

Output:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cannot concatenate 'str' and 'int' objects

The error should make it clear to you that you need to convert theage` object to an integer before adding something to it.

age = "18"
age_int = int(age)
print(age_int+2)

Output:

20

But you should keep in mind some special cases:

1. A floating point(an integer with fractional part) as an argument will return the float rounded down to the nearest whole integer.
   For example : print(int(7.9)) will print 7.
   Also print(int("7.9")) will result an error since the string is an invalid argument to convert to an integer.

   Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ValueError: invalid literal for int() with base 10: '7.9'

2. Also any integer in words if given as an argument will return the same error as above:
   print(int("one")) will give an error as follows: Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: invalid literal for int() with base 10: 'one'

More Information:

Official documentation for int() built-in can be found here