Learn Python By Example – Function Basics

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Function Basics

Create Function Called print_max

def print_max(x, y):

    /* if a is larger than b */
    if x > y:
        print(x, 'is maximum')

    /* if a is equal to b */
    elif x == y:
        print(x, 'is equal to', y)

    /* otherwise */
    else:
        print(y, 'is maximum')

Run Function With Two Arguments

print_max(3,4)
4 is maximum

Note: By default, variables created within functions are local to the function. But you can create a global function that IS defined outside the function.

Create Variable

x = 50

Create Function Called Func

/* Create function */
def func():
    /* Create a global variable called x */
    global x

    /* Print this */
    print('x is', x)
    
    /* Set x to 2. */
    x = 2
    
    /* Print this */
    print('Changed global x to', x)

Run func()

func()
x is 50
Changed global x to 2
x
2

Create Function Say() Displaying x with default value of 1


/* Create function */
def say(x, times = 1, times2 = 3):
    print(x * times, x * times2)

/* Run the function say() with the default values */
say('!')

/* Run the function say() with the non-default values of 5 and 10 */
say('!', 5, 10)

! !!!
!!!!! !!!!!!!!!!

VarArgs Parameters (i.e. unlimited number of parameters)

  • * denotes that all positonal arguments from that point to next arg are used
  • ** dnotes that all keyword arguments from that point to the next arg are used

/* Create a function called total() with three parameters */
def total(initial=5, *numbers, **keywords):
    /* Create a variable called count that takes it's value from initial */
    count = initial
    /* for each item in numbers */
    for number in numbers:
        /* add count to that number */
        count += number
    /* for each item in keywords */
    for key in keywords:
        /* add count to keyword's value */
        count += keywords[key]
    /* return counts */
    return count

/* Run function */
total(10, 1, 2, 3, vegetables=50, fruits=100)
166

 

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