CSC111 Programming Examples Week 2

--D. Thiebaut (talk) 09:12, 6 February 2015 (EST)

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Problem

Here's a problem, below. Read it. And then figure out how you could write a short program that would just be the seed for a solution. Then try to write that small program. And then, in a series of successive small step, you get closer and closer to the solution. I have shown at the bottom of the page my own progression, going from a very simple seed to a fool blown solution. The trick is to do add something fairly simple at every step.

Problem

• Get first name, last name, Id from student, and final grade, as a number (0-100).
• Also known is class average, as a number (0-100).
• Display student information in a box, and horizontal bar graph of 2 grades.

Example of Interaction with the User

 First name?  Dominique
 Last name?   Thiebaut
 Id?          990123456
 Final grade? 90
 +———————————————————————————————————-———————————-+
 |Dominique Thiebaut                    990123456 | 
 +———————————————————————————————————-———————————-+
       00...10...20...30...40...50...60...70...80...90...100
 grade: #############################################
 class: ########################################

(The class average is set by the program, internally. The value used here in 80.)

Decomposition

Below are various steps showing how to progress through the writing of a solution program.

Step 1

Here I try to get the information from the user and display it back. I also spend the time incorporating a header, and various comments that will lay down the outline of where the code will eventually go.

# Exercise1.py
# D. Thiebaut
# 2/6/15
# This program prompts the user for some student information
# including name, Id, and final grade, and displays the result
# nicely formatted.
# Example of output:
#
#+———————————————————————————————————-———————————-+
#|Alex Andra                            990123456 |
#+———————————————————————————————————————————-———-+
#          00...10...20...30...40...50...60...70...80...90...100
#grade: #########################
#class:  #####################
#

# define constants
classAverage = 70

# get user data
fName      = input( "First name?  " )
lName      = input( "Last name?   " )
Id         = input( "Id?          " )
grade   = eval( input( "Final grade? " ) )

# display result
print( fName, lName, Id )
print( grade )
print( classAverage )

Step 2

After verifying that the program works and gets the information well, I realize that I will spend a lot of time entering a the user information as I am debugging the program. So I right away modify the program, so that when I am debugging, I don't have to enter anything. I simply comment out the input statements by putting a #-sign in front of them. This way they actually disappear from the program for the interpreter. Instead I assign constant strings and numbers to the variables.

# define constants
classAverage = 70

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 80 #eval( input( "Final grade? " ) )

# display result
print( fName, lName, Id )
print( grade )
print( classAverage )

Step 3

# define constants
classAverage = 70

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 80 #eval( input( "Final grade? " ) )

# display result
print( "+———————————————————————————————————-———————————-+" )
print( fName, lName, Id )
print( "+———————————————————————————————————-———————————-+" )
print( "          00...10...20...30...40...50...60...70...80...90...100" )
print( grade )
print( classAverage )

Step 4

# define constants
classAverage = 70

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 80 #eval( input( "Final grade? " ) )

# create header
bar = "+———————————————————————————————————-———————————-+"
barLen = len( bar )
userLen = len( "|" + fName+ " " + lName + Id + " |" )
noSpaces = barLen - userLen
infoLine = "|" + fName + " " + lName + (" "*noSpaces) + Id + " |"

# display header
print( bar )
print( infoLine )
print( bar )

# display bar graph
print( "          00...10...20...30...40...50...60...70...80...90...100" )
print( grade )
print( classAverage )

Step 5

# define constants
classAverage = 100

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 80 #eval( input( "Final grade? " ) )

# create header
bar = "+———————————————————————————————————-———————————-+"
barLen = len( bar )
userLen = len( "|" + fName+ " " + lName + Id + " |" )
noSpaces = barLen - userLen
infoLine = "|" + fName + " " + lName + (" "*noSpaces) + Id + " |"

# create bar graph
padding = "       "
scale   = "00...10...20...30...40...50...60...70...80...90...100"

# create user bar
noHashTags = int( grade/2 )
studentBar = noHashTags * '#'

# create class bar
noHashTags = int( classAverage/2 )
classBar = noHashTags * '#'

# display header
print( bar )
print( infoLine )
print( bar )

# display bar graph
print( padding + scale )
print( "grade: " + studentBar )
print( "class: " + classBar )

We note that the scale is not quite accurate and needs to be "pushed" a bit to the right...

Step 6

# Exercise1.py
# D. Thiebaut
# 2/6/15
# This program prompts the user for some student information
# including name, Id, and final grade, and displays the result
# nicely formatted.
# Example of output:
#
#+———————————————————————————————————-———————————-+
#|Alex Andra                            990123456 |
#+———————————————————————————————————————————-———-+
#       00...10...20...40...50...60...70...80...90...100
#grade: #######################################
#class: ##################################
#

# define constants
classAverage = 80

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 70 #eval( input( "Final grade? " ) )

# create header
bar = "+———————————————————————————————————-———————————-+"
barLen = len( bar )
userLen = len( "|" + fName+ " " + lName + Id + " |" )
noSpaces = barLen - userLen
infoLine = "|" + fName + " " + lName + (" "*noSpaces) + Id + " |"

# create bar graph
padding = "      "
scale   = "00...10...20...30...40...50...60...70...80...90...100"

# create user bar
noHashTags = int( grade/2 )
studentBar = noHashTags * '#'

# create class bar
noHashTags = int( classAverage/2 )
classBar = noHashTags * '#'

# display header
print( bar )
print( infoLine )
print( bar )

# display bar graph
print( padding + scale )
print( "grade: " + studentBar )
print( "class: " + classBar )

Step 7

# Exercise1.py
# D. Thiebaut
# 2/6/15
# This program prompts the user for some student information
# including name, Id, and final grade, and displays the result
# nicely formatted.
# Example of output:
#
#+———————————————————————————————————-———————————-+
#|Alex Andra                            990123456 |
#+———————————————————————————————————————————-———-+
#       00...10...20...40...50...60...70...80...90...100
#grade: #######################################
#class: ##################################
#

# define constants
classAverage = 80

# get user data
fName      =  "Alex" #input( "First name?  " )
lName      = "Andra" #input( "Last name?   " )
Id         = "990123456" #input( "Id?          " )
grade      = 70 #eval( input( "Final grade? " ) )

# create header
bar = "+———————————————————————————————————-———————————-+"
barLen = len( bar )
userLen = len( "|" + fName+ " " + lName + Id + " |" )
noSpaces = barLen - userLen
infoLine = "|" + fName + " " + lName + (" "*noSpaces) + Id + " |"

# create bar graph
padding = "      "
scale   = "00...10...20...30...40...50...60...70...80...90...100"

# create user bar
noHashTags = int( grade/2 )
studentBar = noHashTags * '#'

# create class bar
noHashTags = int( classAverage/2 )
classBar = noHashTags * '#'

# display header
print( bar )
print( infoLine )
print( bar )

# display bar graph
print( padding + scale )
print( "grade: " + studentBar )
print( "class: " + classBar )

Step 8

Activate the input() statements, again.

# Exercise1.py
# D. Thiebaut
# 2/6/15
# This program prompts the user for some student information
# including name, Id, and final grade, and displays the result
# nicely formatted.
# Example of output:
#
#+———————————————————————————————————-———————————-+
#|Alex Andra                            990123456 |
#+———————————————————————————————————————————-———-+
#       00...10...20...40...50...60...70...80...90...100
#grade: #######################################
#class: ##################################
#

# define constants
classAverage = 80

# get user data
fName      = input( "First name?  " )
lName      = input( "Last name?   " )
Id         = input( "Id?          " )
grade      = eval( input( "Final grade? " ) )

# create header
bar = "+———————————————————————————————————-———————————-+"
barLen = len( bar )
userLen = len( "|" + fName+ " " + lName + Id + " |" )
noSpaces = barLen - userLen
infoLine = "|" + fName + " " + lName + (" "*noSpaces) + Id + " |"

# create bar graph
padding = "      "
scale   = "00...10...20...30...40...50...60...70...80...90...100"

# create user bar
noHashTags = int( grade/2 )
studentBar = noHashTags * '#'

# create class bar
noHashTags = int( classAverage/2 )
classBar = noHashTags * '#'

# display header
print( bar )
print( infoLine )
print( bar )

# display bar graph
print( padding + scale )
print( "grade: " + studentBar )
print( "class: " + classBar )