Python 2.7: Basics: Variables, Strings, Date and Time
Hands-On | 04 Dec 2016
x = 10
This statement will create a variable called x which will store a number 10. By assigned value python understands that this variable will store numeric data. We can also store other data types, by assigning different types of values:
x_int = 1 x_float = 1.23 x_bool = True
Note that booleans should have an uppercase in the beginning. (True and not true, False and not false)
To print anything on the screen you can use the print function:
In python whitespaces have a significant meaning - they are used to structure code beyond the scope of indentation and formatting. Badly formatted code will result in IndentiationError.
# my comment
""" my comment - mutline line comment """
Python will go beyond the standard math operators provided by the programming languages. In addition to operations like multiplication, addition, subtraction and division, python will provide you with some more interesting operators.
Let's assume you want to raise 2 to a power of 3. This is how we can do it in python:
result = 2 ** 3
Exponentiation is performed in python by using ** operator.
Similar to any other language: x_string = "John" # espace character x_string = 'This is John\'s birthday'
String is actually an array of characters. You can directly access characters by using indexes:
x_string = "Python" # will display the character t print x_string
len() - returns the number of characters in a string
# will print number 5 as a number of characters in the word hello print len("hello")
string.lower() - this method is used to convert all characters to lowercase
# output: hello print "Hello".lower()
string.upper() - converts all characters to uppercase
# output: HELLO print "Hello".upper()
str() - converts non-strings to strings
# creating a float variable pi pi = 3.14 # converting pi to string print str(pi)
Strings can be concatenated using the summation operator +:
# output: Times of our life print "Times " + " of " + " our " + " life "
# output: My score is 50 x_int = 50 print "My score is " + str(x_int)
Another way to print strings by doing string replacement is to format them with %
# output: Jane and Mike were best friends since a long time string_1 = "Jane" string_2 = "Mike" print "%s and %s were best friends since a long time" % (string_1, string_2)
This can be a more interesting exercise:
# input: for first name: [Tom], for last name: [Hanks] # output: Dear Tom Hanks, please proceed to the registration counter first_name = raw_input("What's your first name?") last_name = raw_input("What's your last name?") print "Dear %s %s, please proceed to the registration counter" (first_name, last_name)
Date and Time
The code below displays the current time
# output - will print current time in format of : 2016-11-10 18:18:31.379762 from datetime import datetime now = datetime.now() print now # output: current year, e.g. 2016 print now.year # output: current month, e.g. 11 print now.month # output: current day, e.g. 10 print now.day
just like above, you can also use now.hour, now.minute and now.second