Type Casting is the method to convert the Python variable datatype into a certain data type in order to perform the required operation by users. We will see various techniques for typecasting. There can be two types of Type Casting in Python:
- Implicit Type Conversion
- Explicit Type Conversion
Implicit Type Conversion
Implicit type conversion occurs when Python automatically converts one data type to another during an operation to ensure correct and safe evaluation, without requiring any action from the user.
# Python automatically converts 'a' to int
a = 7
print(type(a))
# Python automatically converts 'b' to float
b = 3.0
print(type(b))
# Python automatically converts 'c' to float as it is a float addition
c = a + b
print(c)
print(type(c))
# Python automatically converts 'd' to float as it is a float multiplication
d = a * b
print(d)
print(type(d))
Output
<class 'int'> <class 'float'> 10.0 <class 'float'> 21.0 <class 'float'>
Explicit Type Conversion
Explicit type conversion is when the programmer manually changes a value’s data type using built-in type casting functions, usually when automatic conversion is not possible or a specific type is needed.
Examples of Type Casting
Commonly used type casting functions in Python are:
- Int() function take float or string as an argument and returns int type object.
- float() function take int or string as an argument and return float type object.
- str() function takes float or int as an argument and returns string type object.
Convert Int to Float
Converting Int to Float in with the float() function.
a = 5
n = float(a)
print(n)
print(type(n))
Output
5.0 <class 'float'>
Python Convert Float to Int
Converting Float to int datatype in Python with int() function.
a = 5.9
n = int(a)
print(n)
print(type(n))
Output
5 <class 'int'>
Python Convert int to String
Converting int to String datatype in Python with str() function.
a = 5
# typecast to str
n = str(a)
print(n)
print(type(n))
Output
5 <class 'str'>
Python Convert String to float
Casting string data type into float data type with float() function.
a = "5.9"
n = float(a)
print(n)
print(type(n))
Output
5.9 <class 'float'>
Python Convert string to int
Converting string to int datatype in Python with int() function. If the given string is not number, then it will throw an error.
a = "5"
b = 't'
n = int(a)
print(n)
print(type(n))
print(int(b))
print(type(b))
Output
5
<class 'int'>
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
/tmp/ipython-input-1957009883.py in <cell line: 0>()
9 print(type(n))
10
---> 11 print(int(b))
12 print(type(b))
ValueError: invalid literal for int() with base 10: 't'
The string "5" is successfully converted into an integer 5. Since 't' is not a number, Python cannot convert it into an integer.
Adding String and Integer Without Conversion
If we try to directly add an integer and a string, Python will throw an error because they are different data types.
a = 5
b = 't'
n = a+b
print(n)
print(type(n))
Output
TypeError: unsupported operand type(s) for +: 'int' and 'str'
We should first convert the string into an integer and then add:
a = 5
b = '7'
# explicit conversion of string to int
n = a + int(b)
print(n)
print(type(n))