How to convert a string to an int in Python
Convert a string to an int
The data types int and string are two primitive data types in Python.
Note: You can read more on data types in Python here.
Python has a built-in method int() that can be used to convert a string to an integer. It can take a string in any number system and convert it to an integer with base 10.
Syntax
The general syntax for the int() method is as follows:
int(value, base [optional])
Parameters
The int() method takes in two parameters:
value: This is the string object that we need to convert.base: This is an optional parameter that specifies the number system. The default value is 10 which represents a decimal number. We can also provide it with a value of 2 to represent a binary number.
Convert a decimal number
If we need to convert a decimal number, the following code can be used:
string_to_convert = "135"converted_int = int(string_to_convert)print("The type after conversion is:", type(converted_int))print("The integer is:", converted_int)
Explanation
Line 2: We call the
int()method.Line 4: We print the type of the converted integer.
Line 5: We print the converted integer.
We can see when we run the code above that the type of the converted_int variable is now int. Since the default value of base for the int() method is 10, we can also rewrite the code above as follows:
string_to_convert = "135"converted_int = int(string_to_convert, 10)print("The type after conversion is:", type(converted_int))print("The integer is:", converted_int)
Convert a binary number
The int() method can also be used to convert a binary number to an integer. For this, we need to specify the value of base as 2, as follows:
string_to_convert = "10001"base = 2converted_int = int(string_to_convert, base)print("The type after conversion is:", type(converted_int))print("The integer is:", converted_int)
Explanation
Lines 1–2: We specify the string and the number system (
base).Line 3: We call the
int()method which handles the conversion.Line 5: We print the variable type.
Line 6: We print the converted number.
Note: The code above can also be used to convert other number systems to integers by specifying the value of the
base. For example, we can convert a string that represents a hexadecimal number to an integer by setting the value ofbaseto 16.
