Function Parameters

A Byte of Python 

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A function can take parameters which are just values you supply to the function so that the function can do something utilising those values. These parameters are just like variables except that the values of these variables are defined when we call the function and are not assigned values within the function itself.

Parameters are specified within the pair of parentheses in the function definition, separated by commas. When we call the function, we supply the values in the same way. Note the terminology used - the names given in the function definition are called parameters whereas the values you supply in the function call are called arguments.

Using Function Parameters

Example 7.2. Using Function Parameters

# Filename:

def printMax(a, b):
	if a > b:
		print a, 'is maximum'
		print b, 'is maximum'
printMax(3, 4) # directly give literal values

x = 5
y = 7

printMax(x, y) # give variables as arguments


$ python
4 is maximum
7 is maximum

How It Works

Here, we define a function called printMax where we take two parameters called a and b. We find out the greater number using a simple if..else statement and then print the bigger number.

In the first usage of printMax, we directly supply the numbers i.e. arguments. In the second usage, we call the function using variables. printMax(x, y) causes value of argument x to be assigned to parameter a and the value of argument y assigned to parameter b. The printMax function works the same in both the cases.