$24
Week 8 Concerts Solution
Overview
This hands-on lab allows you to follow and experiment with the critical steps of developing a program including the program description, analysis, test plan, and implementation with C code. The example provided uses sequential, repetition, selection statements, functions, strings and arrays.
Program Description
Compute the value of the ticket sales for concerts and the total sales for a series of concerts. Then display the concert information in a sorted list.
Technologies used in this project:
strings stored as char arrays
2 dimensional char and int arrays
getting data from the user into the various arrays using only part of an array for valid data
computing array arithmetic – vector inner products to compute a value sorting using selection sort
displaying data in arrays
Interaction
Outline:
Get the ticket price for each 3 categories.
float float float
Get the band name and numbers of fans for each category of each concert.
String int int int
NOTE: spaces are not allowed in the band names, so use underscores instead of spaces.
Period will end the input.
Internal computations:
Compute the value of the sales for each concert.
Compute the total value of the ticket sales.
Sort the concerts by value of the ticket sales.
Display the resulting data in a nice format.
Notes:
This program is not expected to behave nicely if the input does not follow the specifications above.
All numbers this program will handle should be of moderate size. The exact meaning of moderate is made precise by the data types, print statements, and array sizes.
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Analysis
Since we are going to do sorting, we will need to hold the data in arrays.
We will use functions to simplify the code, and reflect a modular approach to the design of the project.
We will use global variables to reduce the amount information transferred in parameter lists.
We will use a fixed number of categories, but let the number of concerts by determined by the user at run time, up to a maximum value.
The user will end inputting the group information with a flag value, a period.
Basic data types
ticket prices – float
name of concert/band – char array
number of concerts and number of fans in each category at each concert – int
number of concerts – int.
value of tickets – float
We will use nested loops to handle most operations:
reading the ticket prices
reading the group name and attendance
computing the value of the ticket sales
printing the array of data
sorting the arrays by the value of the ticket sales
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Pseudo-code:
Global variables:
Constants using define declarations
MAXN – the maximum number of characters in a band name
MAXG – the maximum number of concerts/bands/groups
MAXC – the maximum number of categories
Arrays:
char group [MAXG][MAXN] – the name of each group
int fans [MAXG][MAXC] – the number of fans at a concert by category
float prices [MAXC] – the ticket price of each category
float sales [MAXG] – the total value of the tickets for each concert int count
the actual number of active concerts/bands/groups
this number is determined at run time in the getData function
used throughout the rest of the program to only look at data in the group, fans and sales arrays that is actually active.
Pseudo-Code:
main
getData – get ticket prices by category & get data for the concerts
computeSales – compute sales for each concert
printArray – print raw concert data
sortBySales – sort the concerts by value of sales, use selection sort
findMinSales – find min sales in unsorted rest of array
switchRows – as needed
printArray – print sorted concert data
getData
prompt for ticket prices
get ticket prices into prices array
prompt for band name and fans in each category at each concert
insert data into appropriate arrays, ending with a period
loop on concert
get group name
loop inside on number of categories
computeSales
for each group
sales for that group = 0
for each category
sales = sales + price of category * number of fans in that category
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2.
printArray
print column headers
for each group
print the group name
for each category
print the number of fans in that category
print the sales for that concert/group
sortBySales
COMMENTS: for each row (group + fans + sales)
for each row index, starting at index 0
the rows that have indices less than the current index are sorted, and are already the smallest sales elements in the entire data set.
thus, the next step is to find the smallest sales row in the remaining elements and switch that row with the current index row
for index = 0 to number of active rows, step index by 1
target = findMinSales (index)
if target not equal to index, switchRows (target, index)
findMinSales (index)
set target as index
min
for the rest of the array, starting at index+1, indexing by i
if sales [i] < min
target = i
min = sales [target]
return target
switchRows (m, n)
Temporary locations
char tc
int ti
float v
switch group names by stepping through all the letters (i) in each char array:
tc = group [m][i]
group [m][i] = group [n][i]
group [n][i] = tc
switch fan entries, stepping by (i) over the fans array:
ti = fans [m][i]
fans [m][i] = fans [n][i]
fans [n][i] = ti
switch sales:
v = sales [m]
sales [m] = sales [n]
sales [n] = v
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Test Plan
To verify this program is working properly a variety of test cases should be used.
The following is just one test case, which only tests a very few aspects of the program.
You should be thinking about other data sets to test other aspects of the program, and also create more realistic test sets.
Test
Input
Actual Output using repl.it – user input in red:
Case
1 2 3Enter ticket prices in each of 3 cateogories: 1 2 3
a 1 2 3
-- Enter group and fans
in 3 categories
b 3 3 1
. to finish entries:
a 1 2 3
c 5 3 1
b 3 3 1
d 3 3 5
c 5 3 1
e 1 1 2
d 3 3 5
f 9 4 3
e 1 1 2
g 4 5 6
f 9 4 3
.
g 4 5 6
.
Concert
s1
s2
s3
Sales
a
1
2
3
14.00
b
3
3
1
12.00
c
5
3
1
14.00
d
3
3
5
24.00
e
1
1
2
9.00
f
9
4
3
26.00
g
4
5
6
32.00
--- Sorted ---
Concert
s1
s2
s3
Sales
e
1
1
2
9.00
b
3
3
1
12.00
c
5
3
1
14.00
a
1
2
3
14.00
d
3
3
5
24.00
f
9
4
3
26.00
g
4
5
6
32.00
... bye ...
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Coding Plan
These are the steps taken to develop the base code of this project.
You should start with this code to address the Learning Exercises below.
This is a rather complex project, and it should be developed in SMALL steps, making SMALL changes to the code and testing each change carefully before moving on to the next step. Since we have a pretty good pseudo-code representation of this project, and a good test plan, we should be able to develop the steps we think this project will require.
We are guided here by the requirements of our environment, particularly getting the C compiler to accept our code at each step without error messages.
It is also helpful to have some idea of how long each step should take, so that if our actual time trying to complete a step is getting out of hand, we know it is time to change our strategy for that step by, for example:
taking a break,
looking for more specific information (don’t take too long here either!),
asking someone (your instructor is the best choice) for help!
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Task
Description
Notes
1
Hello world
Get the basic environment working
Get main method started
Even change the message to Bye
2
#define stuff
These tokens will be used in the array declarations, and throughout
the code
Getting the syntax of these declarations correct can be a challenge
3
Declare the arrays
The global variables this program will use.
And count
Get this syntax to work, and work with the define declarations
4
getData function
Just get the declaration to compile correctly
5
Call getData in main
Making sure we have the call syntax correct
6
Other function
As specified in the pseudo-code.
declarations
Again, we want to check with the compiler that we are using the
correct syntax
7
TEST CODE:
Give values for one concert in main:
count = 1
count = 1;
values to one group
// following requires #include <string.h
strcpy (group [0], "one");
fans [0][0] = 3;
fans [0][1] = 12;
fans [0][2] = 33;
sales [0] = 23.23;
8
printArray
Call this function from main.
Focus on getting this function working
Check the output for each step.
Lots of steps:
header line
nested loops: loop over all groups,
the group name, loop over the fan counts, sales
9
More test code
Create another set of code like step 7 to test printArray more
carefully
10
Call getData in main
Start with a printf statement saying “got here” in getData
11
Print prompt
For ticket prices of 3 categories, remove “got here” message
12
Get ticket prices
Use for loop to get prices into sales array
Add for loop to print the values in that array – temporary code
13
Get group loop
For loop to get group name (index is i)
Read group [i]
Add test for name is period and break input loop if so
TEST the period
14
Get fan numbers
Nested for loop over the number of categories (index is j)
Read fans [i][j]
Increment count since this should be a valid group
Temporary: set sales [i] to 44.56 or some other random number
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15
Fix main
Comment out the test code from steps 7 and 9
Insert the appropriate calls in main:
getData ();
printArray ();
Test the code with real data!
16
computeSales
Get this code working, using a loop
Add the call to this function to main
17
Sorting
Get the call to sorting active
Add the print statement to say the following is sorted
Print the “sorted” array (not sorted yet)
18
findMinSales
Get this code working – starting at an index, find the index of the
smallest sales in the rest of the list
Use print statements to make sure this is working
19
switchRows
Get this working – switch group name, the fans and the sales values
20
Final check
Try a number of different data sets here.
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C Code
The following is the C Code that will compile in execute in the online compilers.
C code
This code will compute the values of the sales ticket sales for concerts
and sort the entries by those values
Developer: Faculty CMIS102
Date: Jan 31, XXXX
#include <stdio.h
#define MAXN
100
// max characters in a group/concert name
#define MAXG
50
// max concerts/groups
#define MAXC
3
// max categories
char
group
[MAXG][MAXN];
int
fans
[MAXG][MAXC];
float
prices
[MAXC];
float
sales
[MAXG];
int
count = 0;
void printArray () {
printf ("%15s%5s%5s%5s%10s\n",
"Concert", "s1", "s2", "s3", "Sales");
for (int i = 0; i < count; i++) {
printf ("%15s", group [i]);
for (int j = 0; j < MAXC; j++) {
printf ("%5d", fans[i][j]);
} // end for each category printf ("%10.2f\n", sales [i]);
} // end for each group
} // end function printArray
void computeSales () {
for (int i = 0; i < count; i++) {
sales [i] = 0;
for (int j = 0; j < MAXC; j++) {
sales [i] += prices [j] * fans [i][j];
} // end for each category } // end for each group
} // end function computeSales
void switchRows (int m, int n) {
char tc;
int ti;
float v;
printf ("Switching %d with %d\n", m, n); for (int i = 0; i < MAXN; i++) {
tc = group [m][i];
group [m][i] = group [n][i]; group [n][i] = tc;
} // end for each character in a group name for (int i = 0; i < MAXC; i++) {
ti = fans [m][i];
fans [m][i] = fans [n][i]; fans [n][i] = ti;
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} // end for each fan category v = sales [m];
sales [m] = sales [n]; sales [n] = v;
} // end switch
int findMinSales (int m) {
float min = sales [m];
int target = m;
for (int i = m+1; i < count; i++)
if (sales [i] < min) {
min = sales [i];
target = i;
} // end new max found return target;
} // end function findMinSales
void sortBySales () {
int target;
for (int i = 0; i < count; i++) {
target = findMinSales (i);
if (target i)
switchRows (i, target);
} // for each concert
} // end function sortBySales
void getData () {
// for (int i = 0; i < MAXG; i++) sales [i] = 0;
printf ("Enter ticket prices in each of %d cateogories: ", MAXC); for (int i = 0; i < MAXC; i++)
scanf ("%f", &prices [i]);
printf ("-- Enter group and fans in %d categories\n", MAXC); printf (" . to finish entries:\n"); for (int i = 0; i < MAXG; i++) {
scanf ("%s", &group[i]);
if (group [i][0] == '.')
break;
count++;
for (int j = 0; j < MAXC; j++)
scanf ("%d", &fans[i][j]);
} // end for each group } // end function getData
int main(void) {
getData ();
computeSales ();
printArray ();
printf ("\n --- Sorted ---\n");
sortBySales ();
printArray ();
printf("... bye ...\n");
return 0;
}
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Learning Exercises for you to complete
Demonstrate you successfully followed the steps in this lab by preparing screen captures of you running the lab as specified in the Instructions above.
Add a function to print welcome information, including your name and an introduction to the project, and, of course, call this function as the first instruction in main.
NOTE: It is convenient to put each test case into its own data file so you don’t have to type a rather large set of input over and over again. Then you can just copy/paste the data into the interaction panel of the IDE you are using.
Modify the program to add a function to compute and display the total sales for all the concerts. Support your experimentation with screen captures of executing the new code.
Enhance the program to allow the user to enter 4 categories.
Explain the changes you made to the code, and create appropriate test data files. Support your experimentation with screen captures of executing the new code.
Prepare a new test table with at least 2 more test cases listing input and expected output for the new code you created, supporting 4 categories.
Create a variety of test cases focusing on the sorting algorithm, such as the final element is the smallest, the entire set is already sorted, etc.
Explain the purpose of each test case, and check your code against each of those cases.
Try using different inputs:
What changes would you suggest to handle larger, more realistic numbers?
What happens if any of the numbers, such as the ticket prices, are negative?
What are your recommendations concerning negative input values?
What changes should be made to the code if the customer wished to sort on the number of fans in category 1, the first of the three (or four) categories?
Make those changes, test your code and confirm that it is working correctly.
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Grading guidelines
Exercise
Submission
Points
1
Demonstrates the successful execution of this Lab within an online compiler.
10
Adds and calls a function to display introductory information.
Provides supporting screen captures.
2
Modifies the code to add a function to sum each concert.
10
Supports your experimentation with screen captures of executing the new
code.
3
Modifies the code to handle 4 categories, with explanation.
10
4
Prepares at least 2 additional test cases for 4 categories.
10
5
Prepares test cases focusing on sorting algorithm.
15
Supports your experimentation with screen captures of executing the new
code.
6
Documents experiments with unusual but valid inputs.
10
7
Modifies the code to sort on category 1.
15
Creates appropriate test cases.
Documents results showing correctness of modifications.
8
Document is well-organized, and contains minimal spelling and grammatical
20
errors.
Total
100
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