#!/usr/bin/env python
# coding: utf-8

# In[9]:


# Section 4.5 - sententials
# Definition: A sentential is a special symbol that 
# marks the end of a sequence of values.
#
# Situation: where you have some kind of while loop but
# you don't know how many times the loop should go.
#
# Options:
# 1. - Ask user if they have more information to give to 
#      the computer. (downside: could be cumbersome)
# 2. - Ask at the beginning how many times the loop should
#      go. (downside: can be painful for the user)
# 3. - use a sentential!
#
# Example program -- imagine a doctor who has to insert the
# weights of all patients seen that week, every week. And
# report the average weight.
# Going to use a sentential to "end" the loop.
#
# Write our prompt for the weight like this: 
#     "Enter weight or 0 if no more weights."
#
# Recall: the average of n items is (x1+x2+...+xn)/n

count=0
total_weight=0.0

new_weight=float(input("Insert a weight or insert 0 to stop the program."))
while new_weight != 0:
    total_weight+=new_weight
    count+=1
    new_weight=float(input("Insert a weight or insert 0 to stop the program."))
if count!=0:
    print("The average weight of the",count,"entries is",total_weight/count)


# In[22]:


# Format function -- how to get two decimal points of accuracy
#
var=1489234237498498232.12753575423456877
# the following code will give two decimal points
# it ROUNDS
print(format(var,',.2f'))
# the following gives scientific notation with ("two sig figs"?)
print(format(var,',.2e'))