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Functions

You use the def statement to create a function, as shown in the following example:

def remainder(a,b):
    q = a/b
    r = a - q*b
    return r

To invoke a function, simply use the name of the function followed by its arguments enclosed in parentheses, such as result = remainder(37,15). You can use a tuple to return multiple values from a function, as shown here:

def divide(a,b):
    q = a/b    # If a and b are integers, q is an integer
    r = a - q*b
    return (q,r)

When returning multiple values in a tuple, it's often useful to invoke the function as follows:

quotient, remainder = divide(1456,33)

To assign a default value to a parameter, use assignment:

def connect(hostname,port,timeout=300):
# Function body

When default values are given in a function definition, they can be omitted from subsequent function calls. For example:

connect('http://www.python.org', 80)

You also can invoke functions by using keyword arguments and supplying the arguments in arbitrary order. For example:

connect(port=80,hostname="http://www.python.org")

When variables are created or assigned inside a function, their scope is local. To modify the value of a global variable from inside a function, use the global statement as follows:

a = 4.5
...
def foo():
    global a
    a = 8.8       # Changes the global variable a
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