Parameter List in Function Definition Statements

Q

How to specify parameters in the "def" statement to define a new function in Python?

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A

When defining a function, you can specify the parameter list as a comma separated list of variables with or without default values in the following syntax:

def function_name(variable,variable,...,variable=default_value,...): 
    statement_block

Note that varaibles with default values must be specified after variables without default values.

When calling the function, you must provide values for all parameter variables except parameters with default values.

For example, the profile("Joe",25) expression calls the "profile()" function to be executed with 2 values provided to be assigned to its parameters.

>>> def profile(name,age=25):
...     print("Name: "+name)
...     print("Age: "+str(age))
...
>>> profile("Joe")
Name: Joe
Age: 25

Note that when assigning default value to a function parameter, you can use expressions with any variables available when the "def" statement is interpreted. For example, expression "legalAge+3" is used as the default "age" for the "profile" function:

>>> legalAge = 18
>>> def profile(name,age=legalAge+3):
...     print("Name: "+name)
...     print("Age: "+str(age))
...
>>> profile("Joe")
Name: Joe
Age: 21

 

Defining Functions in Python

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2017-09-09, 119👍, 0💬