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Understanding the Asterisk Operator in Python
In Python, the asterisk (*) serves several unique purposes that differ from its functionality in C language. It plays a crucial role in function definitions and function calls, offering flexibility and conciseness in parameter handling.
Function Definitions
When used in function definitions, the asterisk has two distinct meanings depending on its placement:
Function Calls
In function calls, the asterisk operator is utilized to:
Practical Examples
To illustrate the usage of the asterisk operator:
Positional Arguments:
def get(*a): print(a) # Prints a tuple of excess positional arguments get(1, 2, 3, 4) # Output: (1, 2, 3, 4)
Keyword Arguments:
def get(**kw): print(kw) # Prints a dictionary of excess keyword arguments get(a="Alice", b="Bob", c="Eve") # Output: {'a': 'Alice', 'b': 'Bob', 'c': 'Eve'}
Unpacking Collections:
def add(x, y, z): return x + y + z args = (1, 2, 3) kwargs = {"x": 4, "y": 5, "z": 6} # Unpack tuples and dictionaries result1 = add(*args) # Pass elements of args as individual positional arguments result2 = add(**kwargs) # Pass key-value pairs of kwargs as individual keyword arguments
In summary, the asterisk operator in Python plays a versatile role in function definitions and calls, enabling handling of excess positional and keyword arguments and the unpacking of collections for convenient parameter passing.
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