This tutorial explains user-defined functions in Python.

How to define a function

def keyword is used to create a user defined function.

def functionname(arguments):
    # function body
    #code statements 1
    #code statements 2 to N

For example, Define a function

def add(m,n):
    return m+n;
  • add is a function name
  • m,n are arguments to function
  • return keyword returns the result from a function

Once the function defined, Call the function with arguments

result=add(1,2)
print(result);#3

Functions with multiple return values

Ideally, Functions might return multiple values.

Here is an example

def calculate(m,n):
    sum=m+n
    average=(m+n)/2
    return sum,average;

sum,average=calcuate(6,2)
print(sum);v #8
print(average);#4.0

How to declare a function with default arguments.

Functions can declare multiple arguments, the Caller has to pass all arguments.

Sometimes, the Caller does not pass all arguments, function receives a nil value for not-passed values.

In that case, the Function can be declared with default arguments

Here is an example

def calcuate(m,n=4):
    sum=m+n
    average=(m+n)/2
    return sum,average;

sum,average=calcuate(6,2)
print(sum); #8
print(average);#4.0

sum1,average1=calcuate(6)
print(sum1);#10
print(average1);#5.0