CS110_L1.py

Python3 Editor

#---------------------------------------------------------
#        Print Statements
#---------------------------------------------------------

# printing string literals - can use double quotes " or single quotes '
# must use the same quotation at start of string at the end of the string
print('Hello world')
print(2) # can print integer literals (integer literals use the digit characters only)
print(5.423) # float literals use the decimal point
print() # prints an empty line (used to separate the output)

# can use python as a calculator by putting the operation in a print statement
print(3 * 5) # multiplication
print(3 + 5) # addition
print(3 - 5) # subtraction
print(3 / 5) # division (this one will print 0.6)
print(3 // 5) # floor division (drops all digits after the decimal, this prints 0)
print(34 % 3) # mod - returns the remainder after division 
              # (34/3 = 11 remainder 1. This prints out 1)

# mathematical expressions are evaluated using an operator precendence system like PEMDAS
# in this case, it will evaluate in this order:
# parentheses: (3 + 4) = 7
# division: 7 / 5 = 1.4
# multiplication: 1.4 * 2 = 2.8
# prints out 2.8
print((3 + 4) / 5 * 2) 
print()

# there are also some operators you can use on strings.
# the + operator does concatenation: 
    # adds the string on the right to the end of the string on the left 
print("Hello " + "World")
print("Hello" * 5) # prints out "HelloHelloHelloHelloHello"
#print("Hello" + 3) # causes a TypeError to occur since it cannot add 2 different types

# use the end parameter to set how the print statement ends. 
# By default, this is the newline character, '\n', which causes the next print statement to appear
# on the next line. If you set it to " ", then it will put a space on the end of the print statement
# and the next print will be on the same line.
print("I am a", end=" ")
print("DINOSAUR!")

# escape sequences, same as Java
# \n = newline
# \t = tab
# \" = quote (use this if your string is surrounded by double quotes ")
# \\ = single backslash
print("\tHELLOOOOO")
print("I AM REPTAR\nHEAR ME RAWWWWR")

print()
#-------------------------------------------------------------
#        VARIABLES & INPUT
#-------------------------------------------------------------
# when declaring variables need to initialize them with a value. If you don't know what
# value it will store, set it to None when you create it. But beware, no operations can be done
# on a variable that is a None type.
x = None
# can also set it to a string with quotes, or any other literal (integer, float, boolean, etc.)
x = "Hello"
print(type(x)) # you can view its type by using the built-in function type()

# take in input by using the built-in input() function. The string inside is the prompt that prints
# out before waiting for input.
# store it in a variable to use its value later
x = input("Enter something: ")
print(x)

# input() ALWAYS returns a string. So if you ask them enter an integer, it will come back as a string
a = input("Enter an integer: ")
# if you enter 3 in the above input, the next line will not print out 15, it will print out 33333
print(a * 5)

# if your variable name is yellow, it is a reserved keyword and cannot be used as a variable name
# if your variable name is blue, it is a built-in function and will affect your program later
#     if you try to use that same built-in function

# use triple quotes """ or ''' at the start and end of a string to make a long string
# these can also be used as block comments
print('''Hello
World

This is
a long striiiiing.''')

( around 73 lines Python3 code )

Published By:

Mentor Sabrina

Created on 2020-10-16T18:58:13Z

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