Assignment #3

Due: Tues, June 13

Objective

This assignment will involve practice with control structures, including both selection and repetition statements (loops).

Task

Write the following programs, each in a separate file. Filenames should be:

gas.c
sum.c
numbers.c

(Note that the filenames are all lowercase)

Exercise 1

Filename: gas.c

Write a program that computes miles per gallon, and repeats as many times as the user wishes. It should do the following:

Ask the user to enter the gallons used (use a variable of type double).
- Any time this value entered is not positive, print an error message and make the user re-enter the value.
Ask the user to enter the miles driven (also use type double).
- Any time this value is not positive, print an error message and make the user re-enter the value.
Compute the miles per gallon, and print it, to 4 decimal places.

Sample Runs

(user input is underlined, to distinguish it from output)

Sample run 1

  Enter the gallons used: 13.5
  Enter the miles driven: 200

  The miles/gallon for this tank was 14.8148

Sample run 2

  Enter the gallons used: -4

  Must enter a positive value.  Try again. 
  Enter the gallons used: 0

  Must enter a positive value.  Try again.
  Enter the gallons used: 12.3
  Enter the miles driven: -3

  Must enter a positive value.  Try again.
  Enter the miles driven: -5

  Must enter a positive value.  Try again.
  Enter the miles driven: 0

  Must enter a positive value.  Try again.
  Enter the miles driven: 250

  The miles/gallon for this tank was 20.3252

Exercise 2

Filename: sum.c

Prompt the user and let them enter two integers (we'll call them x and y, for the purposes of this writeup). Compute and print the sum of the ingeters in the range x through y (including the endpoints). Output should look like the sample runs below, and print the addition details from the smallest to the largest number.

(Note: The user input will not necessarily have the lowest number first -- see Sample Run 2. You must take this into account).

Sample Runs

(user input is underlined, to distinguish it from output)

Sample Run 1

  Input two integers: 10 20

  Sum of values from 10 through 20 is:
  10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20
  = 165

Sample run 2

  Input two integers: 9 -4

  Sum of values from -4 through 9 is:
  -4 + -3 + -2 + -1 + 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
  = 35

Sample run 3

  Input two integers: 7 7

  Sum of values from 7 through 7 is:
  7
  = 7

Exercise 3

Filename: numbers.c

Write a program that will allow the user to enter a set of integers (as many as they want), then prints out a summary of information, as follows:

Prompt the user continually to enter a number, until the value 0 is entered, which will be the signal to stop entering values. (This is sometimes known as a "sentinel" value).
Once the sentinel value has been entered, print out the following information:
- The number of positive values that were input
- The number of negative values that were input
- The sum of the input values
- The average (to two decimal places) of the input values
Your output must match mine exactly. See the sample runs below

Sample Runs

(user input is underlined, to distinguish it from output)

Sample Run 1

  Input integer (0 to stop): 12
  Input integer (0 to stop): 4
  Input integer (0 to stop): -1
  Input integer (0 to stop): -5
  Input integer (0 to stop): 18
  Input integer (0 to stop): 0

  # of positives = 3
  # of negatives = 2
  Sum = 28
  Average = 5.60

Sample Run 2

  Input integer (0 to stop): 4
  Input integer (0 to stop): 8
  Input integer (0 to stop): 24
  Input integer (0 to stop): 94
  Input integer (0 to stop): -1
  Input integer (0 to stop): 43
  Input integer (0 to stop): 13
  Input integer (0 to stop): 0

  # of positives = 6
  # of negatives = 1
  Sum = 185
  Average = 26.43

Requirements for all programs

No global variables
All input and output must be done with printf and scanf, using the library stdio.h
You may only use the stdio.h library (you should not need any others for these tasks)
The programs should compile with the Visual C++ compiler
Readable and well-documented source code

Submitting:

Submit only your source code files through the web submission page. This will consist of the following files:

  gas.c
  sum.c
  numbers.c