Leftovers

Make us!

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See the programs arrow.py and triangle.py on the left for a menagerie of solutions.

Using input The input function takes a string as an argument. This string is put the screen to prompt the hapless user to enter something

Whatever the user types is returned as a string.

age = input("Enter your age:  ")
print(age)
print(type(age))
age = int(age)  ##input returns a string!
print(f"The square of your age is {age*age}")

Here we run the program. The $ sign stands for your system's prompt.

$ python get_info.py 
Enter your age:  45
45
<class 'str'>
The square of your age is 2025

Example: Have a user enter two numbers (such as 7 and 8) and have the program print 7*8 = 56 to the screen.

Here is the solution, wabbit.py.

#4*5 = 20
#Amy
number_1 = input("Enter a number: ")
#Ana
number_1 = int(number_1)
#Evan
number_2 = int(input("Enter a second number: "))
#Tristen
print(f"The product of your two chosen numbers is, {number_1} * {number_2} = {number_1*number_2}")

The Grand Scheme: Python Expressions

Wormwood on Steroids

What is the order of operations for a general Python expression?

Operator Types

#1  arithmetic + - * // / % () function()  wormwood
#4  assignment =
#2: relationals:  < > <= >= == !=
#3: boolean and, or, not

x = 7
x = x*2 + 4/5
x = 7*2 + 4/5     substitute
x = 14 + .8       multiply
x = 14.8          add
Assignment makes x poiont at 14.8.


x = 7
y = 2

z = x < 7 or y*y > 3
z = 7 < 7 or 4 > 3           substitute
z = False or True            do relational tests
z = True                     do boolean operations
z now points at True.

z = 4
z = z*4 + 8*7
z = 4*4 + 8*7  substitute
z = 16 + 56    multipwy, elmer
z = 72         add
z now points at  72 

Compound Asssignment Operators These two are the same.

x = x op blah  (op is an infix binary operator)
x op=blah

Here is compound assignmment at work.

>>> x = 13
>>> x += 5
>>> x
18
>>> x *= 4
>>> x
72
>>> x //=10
>>> x
7
>>>