1. 16.216 ECE Application Programming
Instructor: Dr. Michael Geiger
Fall 2011
Lecture 24: Finishing PE4: Functions

2. ECE Application Programming: Lecture 24
Lecture outline
Announcements/reminders
Removing project; programs now worth 60%
Exam 2: Wednesday 11/9
Allowed 1 double-sided sheet of notes
Practice problems to be posted over weekend
Prog. 6 to be posted this weekend; due Mon, 11/14
Prog. 5 grading done today; regrades due Mon, 11/7
No late penalties; will post solution 11/7
Today: Finishing PE4 (functions)
Identify where function(s) can be used
Write code
Test using debugger
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ECE Application Programming: Lecture 24

3. ECE Application Programming: Lecture 24
PE4: Change problem
Given any amount of change under $2.00, determine and print out the minimum number of coins required to make that amount of change.
Available coins are Halves (half dollars), Quarters, Dimes, Nickels, and Pennies.
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ECE Application Programming: Lecture 24

4. ECE Application Programming: Lecture 24
Flowcharting - Sample
Start
scanf amount
nHalves = 0
Given some amount of money, amount, how many half dollars would be returned?
myAmt = amount
myAmt < 0.50
myAmt = myAmt
nHalves = nHalves + 1
printf nHalves
Finish
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ECE Application Programming: Lecture 24

5. Expand to all coins - page 1
Start
nH = 0
scanf amount
myAmt < 0.50
myAmt = amount A
myAmt = myAmt
nH = nH+ 1 B
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ECE Application Programming: Lecture 24

6. ECE Application Programming: Lecture 24B C
nQ = 0
nN = 0
myAmt < 0.25
myAmt < 0.05
myAmt = myAmt
myAmt = myAmt
nQ = nQ + 1
nN = nN + 1
nD = 0
nP = 0
myAmt < 0.10
myAmt < 0.01
myAmt = myAmt
myAmt = myAmt
nD = nD + 1
nP = nP + 1
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ECE Application Programming: Lecture 24 C D

7. ECE Application Programming: Lecture 24D
printf nH,nQ,nD,nN,nP
Finish
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ECE Application Programming: Lecture 24

8. ECE Application Programming: Lecture 24
When to use functions
Find a particular step or series of steps being repeated in your code
If code is exactly the same, you need no arguments
If one or more values change, but the actual calculations that need them are the same, those values can be parameters of your function (arguments)
Reassess change example
Steps for creating change are extremely similar
What changes each time?
How should we use those values in a function?
Inputs, outputs, variables … ?
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ECE Application Programming: Lecture 24

9. ECE Application Programming: Lecture 24B
General case:
nC=number coins Output vC=value of coin Input myAmt=amt left Input/Output
nQ = 0; vQ=0.25
myAmt < vQ
myAmt = myAmt - vQ
nQ = nQ + 1
function: change
nC = 0; vC=input
nD = 0; vD=0.10
myAmt < vC
myAmt < vD
myAmt = myAmt - vC
myAmt = myAmt - vD
nC = nC + 1
nD = nD + 1
return
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ECE Application Programming: Lecture 24 C

10. (addr nC, val vC, addr Amt) change(&nQ,0.25,&myAmt)
Start
General case:
nC=number coins Output vC=value of coin Input myAmt=amt left Input/Output
scanf amount
myAmt = amount
change(&nH,0.5,&myAmt)
function:change
(addr nC, val vC, addr Amt)
change(&nQ,0.25,&myAmt)
change(&nD,0.1,&myAmt)
*nC = 0; vC=input
*myAmt < vC
change(&nN,0.05,&myAmt)
change(&nP,0.01,&myAmt)
*myAmt = *myAmt - vC
printf nH,nQ,nD,nN,nP
*nC = *nC + 1
return
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ECE Application Programming: Lecture 24
Finish

11. ECE Application Programming: Lecture 24
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9/14/2018
ECE Application Programming: Lecture 24