Description
In this workshop, you are to define a global function in type-generic form.
LEARNING OUTCOMES
Upon successful completion of this workshop, you will have demonstrated your
abilities to:
• code a function template
• implement a call to a templated function
• describe the syntax of a constrained cast and its purpose
• describe what you have learned in completing this workshop
SUBMISSION POLICY
The “in-lab” section is to be completed during your assigned lab section. It is to
be completed and submitted by the end of the workshop period. If you attend
the lab period and cannot complete the in-lab portion of the workshop during
that period, ask your instructor for permission to complete the in-lab portion
after the period. If you do not attend the workshop, you can submit the “in-lab”
section along with your “at-home” section (with a penalty; see below). The “athome” portion of the lab is due on the day of your next scheduled workshop
(23:59).
All your work (all the files you create or modify) must contain your name, Seneca
email and student number.
You are responsible to regularly back up your work.
LATE SUBMISSION PENALTIES:
• In-lab portion submitted late, with at-home portion: 0 for in-lab. Maximum
of 7/10 for the entire workshop.
• If any of in-lab, at-home or reflection portions is missing, the mark for the
workshop will be 0/10.
IN-LAB – TEMPLATED FUNCTIONS (60%)
As a secret agent, you have discovered the headquarters of an international
supervillain, a mastermind of crime. In one room you come across an old USB
flash drive containing FBI data on crime statistics in the USA. The data is in file
crimedata_lab.csv. There is some code to analyze the data in files ws9_lab.cpp,
Data.h and Data.cpp. The program that you have found needs to be completed.
You suspect that the data is fake, but you need to prove it. You cannot transmit
the data back to your own headquarters. They have instructed you to complete
the program and to ask 4 questions. They will use your answers to authenticate
the data. While reading the file records, you discover that some records contain
integer data, and some records contain floating-point data.
INPUT FILE FORMAT:
The contents of file crimedata.csv are shown below. You can open the file in excel
to show the columns in spreadsheet form.
The first record has a single integer that holds the number of columns, n, of data
in each record of the file. Each record, other than the first, contains a string (with
no spaces) that describes the data in that record. The data in each record consists
of n comma-separated numbers. These numbers can be integers or floating-point
numbers.
The largest data value allowed in this file is 1,000,000,000. (1 billion, that is, 1
followed by 9 zeros). The smallest number allowed in this file is 0. The field width
for output of each record’s description is 20. The field width for output of each
data field in each record is 15.
The records with integer data are marked:
5
Year,2000,2001,2002,2003,2004
Population,281421906,285317559,287973924,290788976,293656842
ViolentCrime,1425486,1439480,1423677,1383676,1360088
ViolentCrime_Rate,506.5,504.5,494.4,475.8,463.2
GrandTheftAuto,1160002,1228391,1246646,1261226,1237851
GrandTheftAuto_Rate,412.2,430.5,432.9,433.7,421.5
• Year
• Population
• ViolentCrime
• GrandTheftAuto
The records with floating-point data are marked:
• ViolentCrime_Rate
• GrandTheftAuto_Rate
The main() program reads the records in the order that they are in the file, one
record at a time. The readRecord() function reads a single record. After reading
all the data, the program displays the data and ask questions about it.
READROW FUNCTION:
The Data module includes two functions named readRow() with different
signatures. Since both functions contain the same logic, you replace them with a
single templated function of the same name, store the function template in
Data.h, and remove the original function definitions from Data.cpp.
ANSWERS FUNCTION:
You need to complete the answers() function in Data.cpp. The code in it answers
the following questions.
1. Print the total population growth from the beginning to the end of the
data. (Hint: the beginning of the data is at population[0], and the end of
the data is at population[n-1].
2. Between start and finish, did violent crime go up or down?
3. Print the average number of Grand Theft Auto incidents over all the years.
Format it to show millions.
4. Print the minimum and maximum number of Violent Crime incidents.
Notes:
1. You can convert a double to an integer using static_cast
2. The average of an array of numbers is their sum divided by the number of items
in the array.
OTHER FUNCTIONS:
Code the following functions as templated functions and store them in Data.h,
along with your readRecord() templated function.
Function Prototypes
Return
type
Function
name
Template
parameter
Function Parameters Functionality
T min T const T* data,
int n
Returns the smallest element in
data
n is the number of elements in
data
T max T const T* data,
int n
Returns the largest element in
data
T sum T const T* data,
int n
Returns the sum of n elements in
data
Double average T const T* data,
int n
Average is usually computed as a
double in statistics because
sometimes the average is a
fraction between 2 integers.
Note: the average of an array of
n items is the sum of the items /
n
Bool read T std::istream& input,
T* data, int n
Reads n comma-separated data
elements from input. Returns true
if successful, false otherwise.
Void display T const char* name,
const T* data, int n
Display name right-justified in a
field of 20 and each data element
in a field of 15
OUTPUT:
Your output should look like this
Year 2000 2001 2002 2003 2004
Population 281421906 285317559 287973924 290788976 293656842
ViolentCrime 1425486 1439480 1423677 1383676 1360088
ViolentCrimeRate 506.5 504.5 494.4 475.8 463.2
GrandTheftAuto 1160002 1228391 1246646 1261226 1237851
GrandTheftAutoRate 412.2 430.5 432.9 433.7 421.5
Population change from 2000 to 2004 is 12.23 million
Violent Crime trend is down
There are 1.23 million Grand Theft Auto incidents on average a year
The Minimum Violent Crime rate was 463
The Maximum Violent Crime rate was 506
IN-LAB SUBMISSION
To test and demonstrate execution of your program use the same data as the
output example above.
If not on matrix already, upload Data.h, Data.cpp and w9_lab.cpp to your matrix
account. Compile and run your code and make sure everything works properly.
Then run the following script from your account: (replace profname.proflastname
with your professors Seneca userid)
~profname.proflastname/submit 244_w9_lab
and follow the instructions.
Please note that a successful submission does not guarantee full credit for this
workshop.
If the professor is not satisfied with your implementation, your professor may ask you to
resubmit. Resubmissions will attract a penalty.
AT-HOME (40%)
REFLECTION:
1. What happens if you try to put your templated functions in Data.cpp? Does
your source code compile if you move all functions to Data.h? Explain.
2. Move one templated function into ws9_lab.cpp. Does it work now? Do you
need to define the template function above main(), before it is used, or can
you define it below main()?
3. Could you have done this lab without templates, by just overloading your
functions in Data.h to accept integer and double arguments? What is the
advantage of using templates?
4. Are the following equivalent?
template
template
AT-HOME SUBMISSION
To test and demonstrate execution of your program use the same data as the
output example above.
If not on matrix already, upload reflect.txt to your matrix account. Compile and
run your code and make sure everything works properly.
Then run the following script from your account: (replace profname.proflastname
with your professors Seneca userid)
~profname.proflastname/submit 244_w9_home
and follow the instructions.
Please note that a successful submission does not guarantee full credit for this
workshop.
If the professor is not satisfied with your implementation, your professor may ask you to
resubmit. Resubmissions will attract a penalty.
