Python Casting

Specify a Variable Type

There may be times when you want to specify a type on to a variable. This can be done with casting. Python is an object-orientated language, and as such it uses classes to define data types, including its primitive types.

Casting in python is therefore done using constructor functions:

• int() - constructs an integer number from an integer literal, a float literal (by rounding down to the previous whole number), or a string literal (providing the string represents a whole number)
• float() - constructs a float number from an integer literal, a float literal or a string literal (providing the string represents a float or an integer)
• str() - constructs a string from a wide variety of data types, including strings, integer literals and float literals

Example

Integers:

x = int(1)   # x will be 1y = int(2.8) # y will be 2z = int("3") # z will be 3

Show Python »
C:\Users\My Name>python demo_casting_int.py
1                                          
2                                          
3                                          

Example

Floats:

x = float(1)     # x will be 1.0y = float(2.8)   # y will be 2.8z = float("3")   # z will be 3.0w = float("4.2") # w will be 4.2

Show Python »
C:\Users\My Name>python demo_float.py
1.0                                  
2.8                                  
3.0                                  
4.2                                  

Example

Strings:

x = str("s1") # x will be 's1'y = str(2)    # y will be '2'z = str(3.0)  # z will be '3.0'

Show Python »
C:\Users\My Name>python demo_string.py
s1                                    
2                                     
3.0