In this part we will continue our journey with Python.
Note that every thing in Python is an Object and it has a unique id and it has a type e.g
>>> x = 2
>>> id(x)
505498008
>>> type(x)
#showing class is integer
Now lets take a look at below example
>>> y = “”Hyp3ri0n””
>>> id(y)
16153152
>>> type(y)
#showing class is string
Now objects in python can be mutable or they can be immutable.
Mutable can change value , but immutable may not.
Mutable = lists, dictionary
Immutable = numbers, strings, tuples.
Here is a program used to replace a value as per Python version 2 works in 3 but is obsolete.
>>> z = 10
>>> s = “”My age is %s”” %z #Note %s is used to change the value
>>> print (s)
My age is 10
In Python 3 The above code will become
>>> z = 10
>>> s = “”My age is {}”” .format(z)
>>> print (s)
My age is 10
To add a new line we use \n
e.g
>>> s=””My age is 10\nI am happy””
>>>print(s)
My age is 10
I am happy
Functions:
Functions in Python is a method of reusing code. These are very important to understand for our next example.
#!/usr/bin/python3
def main ():
testfunc()
def testfunc():
print(‘Welcome to ITpings’)
if __name__ == ‘__main__’:main()
Now let me explain step by step
To define a function we use def key and functionname () in our case we defined a testfunc()
if we add : at the end of function it means that there must be a value after and the line below must not be empty
In our case the testfucn has a one line code which will print Welcome to ITpings
This function testfunc will be called by the testfunc() under the main(): , because it is duty of main function to call its sub functions.
The last line is a default so that a function must work within a function.
We can also add arguments within the brackets of functions such as
#!/usr/bin/python3
def main ():
testfunc(1,2,3)
def testfunc(a,b,c):
print(‘The numbers are’,a,b,c)
if __name__ == ‘__main__’:main()
The above will print
The numbers are 1 2 3
Now for our better understanding we can use the below program to reuse a same function more than once
#!/usr/bin/python3
def main ():
testfunc()
def testfunc():
for i in range(10):
print(i, end= ‘ ‘)
if __name__ == ‘__main__’:main()
The above will print
0 1 2 3 4 5 6 7 8 9
Now to reuse the same function we will add
#!/usr/bin/python3
def main ():
testfunc()
testfunc()
testfunc()
def testfunc():
for i in range(10):
print(i, end= ‘ ‘)
if __name__ == ‘__main__’:main()
And now it will print
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
Note: Indenting is very important in Python the default rule is to use 4 spaces.
Thanks,
Salman Aftab