There may be times when we 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
Examples:
- Integers:
| Input | print() | Output |
|---|---|---|
| x = int(1) | print(x) | 1 |
| y = int(2.8) | print(y) | 2 |
| z = int("3") | print(z) | 3 |
- Floats:
| Input | print() | Output |
|---|---|---|
| x = float(1) | print(x) | 1.0 |
| y = float(2.8) | print(y) | 2.8 |
| z = float("3") | print(z) | 3.0 |
| w = float("4.2") | print(w) | 4.2 |
- Strings:
| Input | print() | Output |
|---|---|---|
| x = str("s1") | print(x) | s1 |
| y = str(2) | print(y) | 2 |
| z = str(3.0) | print(z) | 3.0 |
in string 3.0 is just a string, not a numeric value