Output and Variables in Python

Output
Output is anything that your program shows on the computer screen. A python program shows or outputs a message such as  Hello World  on the computer screen, using the command print 
print ( "Hello World" )
firstNname = "Alex S."
print ( "Hello" , firstName) # shows message "Hello Alex S"
print ( "Hello %s" %firstName) # shows message "Hello Alex S"
% tells the computer to output a variable type of data, that can either be a number or a string

• %f - outputs a float number. < Ex > print ("Pi = %f, e=%f " %(3.1416, 2.71828) )
• %.2f outputs a float number rounded to two decimals. < Ex > print (" e= %.2f , Pi= %.2f " %(2.71828, 3.1416))
• %i outputs an integer. < Ex > print ("num = %i"  %3)
• %s outputs a String. < Ex > print ("Hello %s, good morning!" %firstName)
• the message above will read:      Hello Alex S. , good morning!

Variable
Variables are names for information that is temporarily stored in your computer memory (RAM).
Variable is a name such as firstName that holds a certain Data Type.  Python Variables can change their own data types.

Python Data Types:

• whole numbers ( int ) < Ex > 3 ,   101,   15...
• decimal numbers ( float ) < Ex > 3.14,    2.72,   101.181...
• strings ("  ") < Ex > "Alex S" , "Hello World!"
• lists ( [ ] ) < Ex > [ 1, 2, 3, 4, "Alex",  'c' ]

Comment - any red text line that starts with #  this part of the program is not considered as "instructions" by the compiler
Compiler - the program which turns your code into an actual program
Multiline Comment - comments that can go on multiple lines. Start and End these with three single quotes '''  '''
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