Lab 3: A Resistor Network Program Solution

    • Objectives

The objective of this assignment is to provide you with a practical introduction to programming with C++ objects. This assignment requires you to complete the implementation of two classes and their associated member functions, as well as performing basic I/O operations with formatting.

    • Problem Statement

Your task is to implement a program for storing resistors in a circuit. The circuit, or network, is de ned by a number of nodes, each node being connected to one or more resistors. Each resistor has certain values associated with it, including: resistance value, text name, and the IDs of the two nodes (endpoints) it connects. The diagram below (Fig 1) illustrates an example. Here R1 connects nodes 1 and 2, R2 does the same, and R3 connects nodes 1 and 3. The nodes could be strips on a breadboard for example, with resistors plugged in to some nodes.

The program you will write is similar to the \input-and-store-the-network" portion of real programs used to simulate electric circuits, and programs that control the robots that automatically insert resistors connecting the appropriate points (nodes) on circuit boards.


























Figure 1: Example circuit

Circuits are input using a text-based user interface, which will require you to extend the com-mand parser you developed in lab2. Commands are de ned to allow the user to insert, modify, delete and print resistors, and to set the maximum size of the network. Based on the commands given, you will need to maintain two arrays, one of Resistors and one of Nodes, to which you can add and modify elements.





Page 1 of 10
ECE244    Programming Fundamentals    Fall 2017



    • Preparation & Background

The key concepts in this lab are the creation and use of classes. You should review the textbook and lecture notes pertaining to the following topics:

Dynamic memory allocation and arrays Constructors and destructors

Class member variables and functions Public/private access types

    • Speci cations

The commands your program must accept are those speci ed in Table 2 of lab 2, along with one new command to set the maximum size of the network. However, while in lab2 you had only to check that the commands were syntactically valid, in this lab you will actually store the resistors and their connectivity in two arrays (of Resistors and of Nodes) and output the correct data in response to the print commands.

The rst line of input to your program will set the maximum allowed node number and the maximum number of resistors:

maxVal maxNodeNumber maxResistors

where both maxNodeNumber and maxResistors are positive integers. You should store these two values in variables in your program and also use them to specify the appropriate size for the resistor and node arrays your program will require. Use the new[] operator to allocate the node and resistor arrays. If your program is sent several maxVal commands during one run, you will have to ensure that for any maxVal command after the rst one you delete any already allocated Node and Resistor arrays, and then allocate the arrays to the speci ed new sizes. The node and resistor arrays and any other necessary variables should be initialized to the empty network state (no resistors stored) after any maxVal command.

The resistor index shall be the position of the resistor in the resistor array, starting at 0. The program shall be able to accommodate exactly maxResistors, as speci ed in the maxVal command. The nodes to which these resistors can be attached are identi ed by an integer ID, which corresponds to their index in the node array. You must be able to store data for node indices from 0 to maxNodeNumber, inclusive, where maxNodeNumber is set by the maxVal command. Each node can accomodate only a limited number of resistors attaching to it (think of the number of holes in a breadboard strip); this is a #define constantMAX RESISTORS PER NODE which is set to 5 for this lab. The node and resistor arrays shall be sized according to the maxVal command, start empty and be modi ed based on user commands as de ned below in Sec 4.2. The command parser must check its input for validity, catching and reporting the errors de ned in Sec 4.3. Lastly, successful commands must update the data structures and produce output conforming to Sec 4.2. Additional restrictions on how the program is to be written and organized are detailed below.


4.1    Coding Requirements

    1. You shall create classes Node and Resistor to store your network, starting with the provided de ntions.



Page 2 of 10
ECE244    Programming Fundamentals    Fall 2017



    2. The provided header les Node.h and Resistor.h shall contain only the class de nitions for Node and Resistor respectively. They may be modi ed to add additional member data and functions. The access type (public/private), arguments, and return types of the existing functions shall not be changed.

    3. You shall create source les Node.cpp and Resistor.cpp to contain the function de nitions for the two classes. Non-class-member functions (parsing, printing, main, etc.) should be stored in separate les.

    4. Any class member variables that are added shall be of private access type. You may provide public accessor functions to set and get values where necessary.

    5. All I/O shall be from cin/cout using the operators << and >>. You may use peek(), getline(), and stringstreams as in the previous lab.

    6. You should reuse your parser from lab2. If you did not detect all invalid input in lab 2 all is not lost { the grading for this lab will not check many parsing errors from lab 2. The only errors you need to detect are those speci ed in Sec 4.3.

4.1.1    Class Resistor

Each object of the Resistor class holds information about one resistor in the network. You must create a le Resistor.cpp containing implementations for the functions indicated in Resistor.h below (Fig 2). Each resistor object has a string (name), a resistance value in Ohms (resistance), and the IDs (indices in the node array) of the two nodes to which it is connected (endpointNodeIDs[2]). There are also constructor and destructor functions to initialize the class, a function to print the values, and functions to set/get the data members of the class. You may add data members and methods, but must adhere to the restrictions outlined in Sec 4.1 above.

The program shall store all resistors in an array, starting at element 0 for the rst resistor added and incrementing from there. When adding a Resistor to a Node, the resistor shall be referred to by its position in the resistor array, also known as its resistorID.

4.1.2    Class Node

The starter code for class Node is shown below. The variable numRes is intended to store the number of resistors currently attached to the node. It should start at zero, and increment each time a resistor is added.

4.2    Input and Output

Input shall be accepted as speci ed in lab 2, except you do not have to handle the deleteR name command (but you do have to handle deleteR all). The meaning of the commands shall be as indicated in Table 1.

For each valid line of input (ie. each line not causing an error as de ned in Section 4.3), one or more lines of output shall be produced as described in Table 1 and below. The values in italics must be replaced by either the value given in the command, or the value already stored (eg. resistance old in the modifyR output de ned in Table 1). Strings must be reproduced exactly as entered. An example session is provided in Sec 6 to illustrate this.






Page 3 of 10
ECE244    Programming Fundamentals    Fall 2017



    • /*

    • * File:   Resistor.h

    • * Author: JC and VB

    • *

    • * Created on October 6, 2013, 1:01 PM

    • */

7

    • #ifndef RESISTOR_H

    • #define RESISTOR_H

10

    11 #include <string>

    12 #include <iostream>

    13 using namespace std;

14

    15 class Resistor

    16 {

    17 private:

    18 double resistance=0.0; // resistance (in Ohms)

    19 string name; // C++ string holding the label

    20 int endpointNodeIDs[2]; // IDs of nodes it attaches to

21

    22 public:

    23 Resistor(int rIndex_,string name_,double resistance_,int endpoints_[2]);

    24 // rIndex_ is the index of this resistor in the resistor array

    25 // endpoints_ holds the node indices to which this resistor connects

26

    27 ~Resistor();

28

    29 string getName() const; // returns the name

    30 double getResistance() const; // returns the resistance

31

    32 void setResistance (double resistance_);

33

    34 // you *may* create either of the below to print your resistor

    35 void print ();

    36 friend ostream& operator<<(ostream&,const Resistor&);

    37 };

38

    39 ostream& operator<<(ostream&,const Resistor&);

40

41    #endif    /* RESISTOR_H */

42


Figure 2: Starter de ntion for class Resistor (you may add to this, but not modify what is given)


4.2.1    Printing resistance information (printR command)

Resistor information shall be printed as:

name resistance Ohms nodeid -> nodeid

The two nodes shall appear in the order in which they were presented in the insertR command that created the resistor. The name eld shall be 20 characters wide, aligned on the left side and padded with spaces. The resistance eld shall be eight characters wide, show two digits after the decimal place, and be aligned on the right side1. An example is shown below. The underscore characters are intended to show padding spaces that are part of the column widths


    • See the setw and left IO manipulators


Page 4 of 10
ECE244    Programming Fundamentals    Fall 2017



    • /*

    • * File:   Node.h

    • * Author: JC and VB

    • * Author: TSA

    • *

    • * Updated on August 24, 2016, 01:40 PM

    • * Created on October 6, 2013, 12:58 PM

    • */

9

    10 #ifndef NODE_H

    11 #define NODE_H

12

    13 #define MAX_RESISTORS_PER_NODE 5

14

15

    16 class Node

    17 {

    18 private:

19

    20 int numRes=0; // number of resistors currently connected

    21 int resIDArray[MAX_RESISTORS_PER_NODE]; // stores the index of each resistor connected

22

    23 public:

    24 Node();

    25 ~Node();

26

    27 // Checks to see if the resistor can be added to poistion rIndex

    28 // in the resistor array. Returns true if yes, otherwise false.

    29 bool canAddResistor(int rIndex);

30

    31 // Updates resIDArray to make the resistor in position rIndex in

    32 // the resistor array connected to this node.

    33 void addResistor (int rIndex);

34

    35 // prints the whole node

    36 // nodeIndex is the position of this node in the node array.

    37 void print (int nodeIndex);

38

    39 };

40

41    #endif    /* NODE_H */

42


Figure 3: Starter de ntion for class Node (you may add to this, but not modify what is given)

de ned above. All columns shall be separated by a single space.

R20_________________ __150.00 Ohms 1 -> 3

When using the printR command, the output above is preceded by a single line of output,

Print:

Print:

R20_________________ __150.00 Ohms 1 -> 3

For printR all the output is the same, except there are multiple resistances printed, one per line. Resistors should be printed in the same order in which they were entered.

Page 5 of 10

ECE244

Programming Fundamentals
Fall 2017













Command
Arguments
Output if valid
Action if valid






maxVal
maxNodeNumber
New network:  max node num-
Node array created with new[] to

maxResistors
ber is maxNodeNumber; max re-
store nodes from 0 to maxNode-


sistors is maxResistors
Number  and Resistor array cre-





ated to store up to maxResistors;





the network is initialized to empty





(no resistors).
insertR
name resistance
Inserted: resistor name resistance
Adds 1 resistor to Resistor ar-

nodeid nodeid
Ohms nodeid -> nodeid
ray and updates 2 entries in Node





array
modifyR
name resistance
Modi ed: resistor name from re-
Updates  one  entry  in  Resistor


sistance

old Ohms to resistance
array


Ohms


printR
name
Print: resistor info (see below)
No data changed
printR
all
Print: resistor info (see below)
No data changed
printNode
nodeid
Print: node info (see below)
No data changed
printNode
all
Print: node info (see below)
No data changed
deleteR
all
Deleted: all resistors
All resistors cleared and Node ar-





ray updated so we have an empty





network








Table 1: Valid commands and arguments

4.2.2    Output from printNode command

The output from the printNode command is shown below, assuming that printNode 1 was entered.

Print:

Connections at node 1: 2 resistor(s)

R20_________________ __150.00 Ohms 1 -> 3

Rfb_________________ ___20.13 Ohms 1 -> 4

For each node, a header line shall be printed indicating the number of attached resistors. Following that line, all connected resistors shall be printed in the order in which they were added, formatted as in Sec 4.2.1, but with each resistor line indented by two spaces. If no resistors are attached, no resistor lines are printed. The header line shall be printed as (note there are no double-spaces anywhere despite appearances):

Connections at node nodeid :    count  resistor(s)

The output from printNode all is the same, except data for each node is printed, from nodeid (index) 0 to maxNodeNumber inclusive. Note that each resistor will appear twice, once per node to which it is connected. For example:

Print:


Connections at node 0:
0
resistor(s)
Connections at node 1:
2
resistor(s)
R20_________________
__150.00 Ohms 1 -> 3

Page 6 of 10

ECE244

Programming Fundamentals
Fall 2017




Rfb_________________
___20.13
Ohms 1 -> 4

Connections at node 2:
0
resistor(s)

Connections at node 3:
1
resistor(s)

R20_________________
__150.00
Ohms 1 -> 3

Connections at node 4:
1
resistor(s)

Rfb_________________
___20.13
Ohms 1 -> 4


4.3    Error Checking

The program must check that the input is valid. Your program must check for the error conditions listed in the table below and output the speci ed message. It is ne if your program checks for the other error conditions listed in lab 2, but those errors will not be tested in this lab, as they were already graded in lab 2. If a command has any error (e.g. does not parse correctly, or the insertR command fails due to inadequate space in either the resistor or node array), the network (arrays and related variables) shall remain unchanged. As in lab 2, at most one error message shall be printed per line of input. In the messages, italicized values such as R should be replaced by the value causing the error.

Error message output must comply exactly (content, case, and spacing) with the table below to receive credit. There are no trailing spaces following the text.

Error message



Cause










Error: maxVal arguments must be
maxNodeNumber  or maxResistors  was speci ed to be 0 or
greater than 0



negative
Error: resistor name not found
When searching for a resistor by name (eg. in modifyR, printR),







a resistor with the given name was not found
Error:
node  value
is
out  of
An integer nodeid value has been provided that is outside the
permitted
range   lower

bound-
legal 0 to maxNodeNumber range





upper

bound











Error: resistor array is full


There are no more spaces in the resistor array to accommodate







the resistor being added
Error: node is full



One   of   the   endpoint   nodes   is   already   full   (has







MAX

RESISTORS

PER

NODE resistors already attached)
Error: resistor name already exists
When adding a new resistor, the resistor name alread exists
Error:
both
terminals
of
resistor
When adding a new resistor, both ends of the resistor are con-
connect to node nodeid



nected to the same node















Table 2: Errors to be reported in this lab.

The program is not required to deal with errors other than those listed in the table above. If more than one error message is applicable for a single line of input, the error message listed rst


Page 7 of 10
ECE244    Programming Fundamentals    Fall 2017



in Table 2 should be printed (i.e. the errors in Table 2 are listed in descending priority order).

    • Helpful Hints

You may (and are encouraged to) recycle the parser from the previous lab. You will need to make a few minor changes and add the maxVal command.

Before submitting, remember to use exercise to test your program. Don’t forget that exercise covers only some possible input; when graded your program will be tested with some of the test cases in exercise and some additional test cases. Accordingly, you should read the speci cation above carefully and create some additional test cases of your own.

You will need to store one array of Nodes and one of Resistors - global scope is acceptable for a program of this scale. You will also need a variable such as resCount to count the number of resistors already added, and will need variables to store maxNodeNumber and maxResistors.

For output formatting (padding, left/right justify, precision control) you should look at the <iomanip> header  le2. Functions like left, right, setfill, and setw will be of great help.

Add features one-by-one. Even if you cannot complete every command (or detect every error), you should still submit your program since it may pass some test cases.

Your program should delete all the memory it allocates with new before it exits; this is good practice and ensures there are no memory leaks. The autotester will check if your program deletes all the memory it should and you will lose marks if you do not. A good way to check if you have deleted all the memory you allocated with new is to run the valgrind memory checking program. A tutorial on valgrind will be posted to the portal, and you are encouraged to learn and use this tool.

    • Example Session

> maxVal 0 1

Error: maxVal arguments must be greater than 0

> maxVal 6 7

New network:
max node
number is 6; max
resistors is 7
> insertR R0
100.1
0 1




Inserted: resistor
R0
100.10
Ohms 0 ->
1
> insertR R0
333.33 0
2



Error: resistor R0
already exists


> insertR R1
110.001 0 2



Inserted: resistor
R1
110.00
Ohms 0 ->
2
> insertR R2
120 0
3




Inserted: resistor
R2
120.00
Ohms 0
->
3
> insertR R3
130 0
4




Inserted: resistor
R3
130.00
Ohms 0
->
4
> insertR R4
140 0
5




Inserted: resistor
R4
140.00
Ohms 0
->
5

    • insertR R5 150 0 6 Error: node is full

    • insertR R6 160 1 7

Error: node 7 is out of permitted range 0-6


    • www.cplusplus.com/reference/iostream is a good reference


Page 8 of 10
ECE244    Programming Fundamentals    Fall 2017



> insertR R7 170 1 5



Inserted: resistor R7
170.00
Ohms 1
-> 5
> insertR R8 180 4 3



Inserted: resistor R8
180.00
Ohms 4
-> 3
> insertR R9 190 2 4



Error: resistor array
is full


> printR R8



Print:




R8    180.00 Ohms 4 -> 3

> printR R9

Error: resistor R9 not found

    • printR all Print:

R0
100.10
Ohms 0 -> 1
R1
110.00
Ohms 0 -> 2
R2
120.00
Ohms 0 -> 3
R3
130.00
Ohms 0
-> 4
R4
140.00
Ohms 0
-> 5
R7
170.00
Ohms 1
-> 5
R8
180.00
Ohms 4
-> 3

    • printNode 1 Print:

Connections at node 1: 2 resistor(s)

R0
100.10
Ohms
0
->
1
R7
170.00
Ohms
1
->
5

    • printNode all Print:

Connections at node 0: 5 resistor(s)

R0
100.10
Ohms 0 -> 1
R1
110.00
Ohms 0 -> 2
R2
120.00
Ohms 0 -> 3
R3
130.00
Ohms 0 -> 4
R4
140.00
Ohms 0 -> 5
Connections at node 1: 2 resistor(s)
R0
100.10
Ohms 0 -> 1
R7
170.00
Ohms 1 -> 5
Connections at node 2: 1 resistor(s)
R1
110.00
Ohms 0 -> 2
Connections at node 3: 2 resistor(s)
R2
120.00
Ohms 0 -> 3
R8
180.00
Ohms 4 -> 3
Connections at node 4: 2 resistor(s)
R3
130.00
Ohms 0 -> 4
R8
180.00
Ohms 4 -> 3
Connections at node 5: 2 resistor(s)
R4
140.00
Ohms 0 -> 5
R7
170.00
Ohms 1 -> 5

Connections at node 6: 0 resistor(s)

> modifyR R3 2.5

Modified: resistor R3 from 130.00 Ohms to 2.50 Ohms

> printR R3

Print:

R3    2.50 Ohms 0 -> 4

> maxVal 3 4

New network: max node number is 3; max resistors is 4

    • printNode all Print:

Connections at node 0: 0 resistor(s)

Connections at node 1: 0 resistor(s)


Page 9 of 10
ECE244    Programming Fundamentals    Fall 2017



Connections at node 2: 0 resistor(s)

Connections at node 3: 0 resistor(s)

> insertR bigres 1000 2 3

Inserted: resistor bigres 1000.00 Ohms 2 -> 3

> insertR smallres 0.05 2 4

Error: node 4 is out of permitted range 0-3

> printR all

Print:

bigres    1000.00 Ohms 2 -> 3

    • deleteR all Deleted: all resistors

    • printR all

Print:

>

    • Procedure

Create a sub-directory in your ece244 directory, and set its permissions so no one else can read it. Create a Make le or NetBeans project to build a program called rnet starting with the provided les. Write and test the program to conform to the speci cations laid out in Sec 4.

The hints in Sec 5 may help get you started, and the example session in Sec 6 may be used for testing.

    • Deliverables

You must submit all source    les to permit your project to compile. They should be:

Main.cpp

Rparser.cpp (a modi ed version of Parser.cpp from previous lab) Rparser.h (containing function prototypes for the parser)

Resistor.h Resistor.cpp Node.h

Node.cpp

As before, it is essential that your program produce output exactly as speci ed: no additional or missing parts.

Submit the    les using ~ece244i/public/submit 3.












Page 10 of 10