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Lab3.pdf
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CMIS 102 Hands-On Lab
Week 3 – Trapezoid araa
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, design, pseudocode visualization, and
implementation with C code. The example provided uses mathematical operators and variable types.
Program Description
This program will calculate the area of a trapezoid. The program will ask the user to enter the two bases
and height and then use these values to calculate and then print the area of the trapezoid. The design
step will include pseudocode.
Analysis
I will use sequential programming statements.
I will define three float numbers for the two bases and the height: baseA, baseB, height.
Float numbers were selected as opposed to integers to make sure trapezoids of all dimensions are
possible and not just whole numbers.
Float number will store the area: area
The area will be calculated by this formula:
Area = ½ * (baseA + baseB) * height
For example if the bases are 4.7 and 2.1, and the height is 5.3 the area is calculated as:
Area = ½ * (4.7 + 2.1) * 5.3 = ½ * 6.8 * 5.3 = 3.4 * 5.3 = 18.02
Test Plan
To verify this program is working properly the following baseA, baseB and height values could be used
for testing:
Test Case baseA baseB height Expected Output Notes:
1 3 4 5 17.5 Small integers
2 5 5 5 25 Square or Rhombus
3 0 3 4 6 Triangle
4 10.1 8.3 12.2 112.24 Some fractions
5 2.67 6.23 3.23 14.3735 More fractions
6 120 450 874 249090.000 Larger numbers
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Pseudocode
// This program will calculate the area of a trapezoid.
// Declare variables
Declare baseA, baseB, height, area as Float
// Ask User for Inputs
Write “Enter the first trapezoid base:”
Input baseA
Write “Enter the second trapezoid base:”
Input baseB
Write “Enter triangle height:”
Input height
// Set value of area
Set area=1/2*(baseA + baseB) * height
// Print area
Print “Area of the trapezoid is “ + area
C Code
The following is the C Code that will compile in execute in the online compilers.
// C code
// This program will calculate the area of a trapezoid.
// Developer: Faculty CMIS102
// Date: Jan 31, XXXX
#include <stdio.h>
int main ()
{
/* variable definition: */
float baseA, baseB, height, area;
/* Prompt user for baseA */
printf("Enter the first base of the trapezoid: \n");
// Input the base
scanf("%f", &baseA);
/* Prompt user for baseB */
printf("Enter the second base of the trapezoid: \n");
// Input the baseB
scanf("%f", &baseB);
/* Prompt user for height */
printf("Enter the height of the trapezoid: \n");
// Input the height
scanf("%f", &height);
// Calculate the Area
area= 0.5 * (baseA+ baseB) * height;
// Print the result
printf("Area is : %f\n", area);
return 0;
}
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Setting up the code in repl.it:
And the conversation panel:
Note the bases and height (4.7, 2.1 and 5.3) are entered in as responses to the prompts.
You can change these values to any valid float values to match your test cases.
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Learning Exercises for you to complete
1. Demonstrate you successfully followed the steps in this lab by preparing screen captures of you
running the lab as specified in the Instructions above.
2. Change the C code to calculate the perimeter of the corresponding right trapezoid, where two
of the angles are 90°. Support your experimentation with a screen capture of an execution of
the new code. A little geometry, using the Pythagorean Theorem, will derive the following
formula for the perimeter:
P = baseA + baseB + height + squareRoot (height^2 + (baseA – baseB)^2)
Which can be coded as: perimeter = baseA + baseB + height +
sqrt (height*height + (baseA – baseB)*(baseA – baseB))
NOTE: The code will also need the following include statement added just after the
“#include <stdio.h>“ line in the code: #include <math.h>
3. Prepare a new test table with at least 3 distinct test cases listing input and expected output for
the perimeter of a right trapezoid.
4. What is this line of code doing?
scanf("%f", &height);
How would you change this line if you wanted to input an Integer as opposed to a float?
5. What are the values of g and h after executing the following C code?
#include <stdio.h>
int main(void) {
int i,j;
float f,g,h;
i = 5; j = 2;
f = 3.0;
g = f + j / i;
h = (f + j)/i;
printf("values of g,h are %f,%f\n", g,h);
return 0;
}
Describe specifically, and in your own words, why are the values of g and h different? Support your experimentation with a screen capture of an execution of the code.
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Submission
Submit a neatly organized word (or PDF) document that demonstrates you successfully executed this lab
on your machine using an online compiler. You should provide a screen capture of the resulting output.
Also, provide the answers, associated screen captures, C Code and descriptions of your successful
completion of all learning exercises listed above.
The answers to the learning exercises, screen captures, C code and descriptions can be included in the
same neatly organized document you prepared as you ran this lab. Note the code can be embedded in
the word document. However; be sure all code compiles and runs perfectly before submitting the
document.
Submit your document no later than the due date listed in the syllabus or calendar.
Grading guidelines
Exercises Submission Points
1 Demonstrates the successful execution of this Lab within an online compiler.
Provides supporting screen captures.
20
2 Modifies the code to also calculate the perimeter of a right trapezoid. 20
3 Provides a new test table with at least 3 distinct test cases listing input and
expected output for the perimeter of a right trapezoid.
20
4 Accurately describes the purpose of the scanf code. Accurately describes how to
modify the code to input an integer as opposed to a float.
20
5 Accurately describe why are the values of g and h different for the provided code?
Supports your experimentation with screen captures of executing the code.
10
6 Document is well-organized, and contains minimal spelling and grammatical
errors.
10
Total 100
