Take Home Lab #2
Problem 1: Bank
Problem 1: Bank (1/5)
3
 Manage customers’ bank account using following
operations:
• Create a new account given a customer’s name and
initial account.
• Deposit money to a customer’s account
• Withdraw money from a customer’s account and report
whether the transaction is successful or not.
Problem 1: Bank (2/5)
4
 Class Account
Attributes:
private:
int balance; // store the current account balance
string name; //store the customer’s name
Problem 1: Bank (3/5)
5
 Class Account
Methods:
public:
//constructor
Account (int balance, String name);
//setter, getter
string getName();
…
void setName(string new_name);
Problem 1: Bank (2/5)
6
 Class Bank
Attributes:
private:
int num_of_acc; //store the number of account in a bank
double interest; //store the interest rate
Account* acc_list[101]; //store the pointers to the accounts
Problem 1: Bank (3/5)
7
 Class Bank
Methods:
public:
//constructor
Bank (double new_interest);
void create (string name, double value);
void deposit(string name, double value);
void withdraw(string name, double value);
void getInfo(int month, Account* result[]);
//getInfo transfers the account list to the result array
//can also be implemented with vector<Account*>
Problem 1: Bank (5/5)
8
 Input: Process until “0” is read.
cin >> operation;
while (operation!=“0”)
{
//Process the input
cin >> operation;
}
//Print the final balance of all customers.
Problem 2: Social Network
Pointers as returning values of Methods
1: Person * addPerson(string name){
2: Person * p = new Person(name);
3: persons.push_back(p);
4: return p;
5: }
6: Person * x = addPerson(“Acer”)
Pointers as returning values of Methods
 Line 4 returns the address of the newly created
person (named “Acer”) to Line 6. Then x will point to
the same Object as p does. x and p are not Persons,
they are pointers to persons.
x
Person{“Acer”, <groups of
p
Acer>}
Distinction
1’: Person addPerson(string name){
2’: Person p = Person(name);
3’: persons.push_back(p);
4’: return p;
5’: }
6’: Person x = addPerson(“Acer”)
Distinction
 Line 4 returns the newly created person (named
“Acer”) to Line 6. Then x will have the same value as
p. x and p are both Persons, and they points to
different addresses which contain the same value.
x
p
Person {“Acer”, <groups
of Acer>}
Person {“Acer”, <groups
of Acer>}
Social Network 1
 Person
 name: string
 vector <int> group // the group ids of the person’s groups
 Group
 name: string
 id: int
 vector <Person *> members
 SocialNetwork
 vector<Person *> persons
 vector <Group *> groups.
 Methods to process queries.
Tasks
 For all operations, find the person in the person list.
Create a new person object if the person has not been
mentioned before.
 Createjoin


First, check whether the group name already exist. If not exist,
create a new group with the assigned name.
Add the person into the group.
 Quit
 Find the person in the member list of the group and remove it
 Find the group in the person’s group list, and remove it.
Tasks
 Query 1
 Just go through the group list to find the one with maximum
member.size()
 Query 2
 Go through every person x in the person list
Counting the number of x’s acquaintances by going through every
person y in the person list
 Check whether x knows y by going through x’s and y’s group list.
If they are in some same group (if their group lists have some
common elements), then they know each other.
 Update the person who has the maximum number of
acquaintances.

Code for Query 2
 string SocialNetwork::answerQuery2(){

int k = -1;

int max_know = -1;

for (int i=0; i<persons.size(); i++){

int num_know = 0;

for (int j=0; j<persons.size(); j++){

if (i==j) continue;

if (persons[i]->know(persons[j])) num_know++;

}

if (num_know > max_know || num_know == max_know && persons[i]





>getName() <persons[k]->getName()){
max_know = num_know;
k = i;
}
}
return persons[k]->getName();
}
Problem 3: File
Problem
 Create files and folders
 Delete a file from a folder
 Move a file to other folder
 Count the size of a folder
 Find the folder with largest size
File Class
File.h
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
class File {
private:
string name;
int size;
string foldername;
public:
File();
File(string name, int size, string foldername);
string getName();
int getSize();
string getFolderName();
void setFolderName(string foldername);
};
Folder Class
Folder.h
#include <cstdlib>
#include <cstring>
#include <vector>
#include "File.h"
using namespace std;
class Folder {
private:
string name;
vector<File*> files;
public:
Folder(string name);
string getName();
void addFile(File* file);
void deleteFile(File* file);
int countSize();
};
deleteFile()
 loop through vector<File*> files,
 find the file you want to delete.
void Folder::deleteFile(File* file)
{
for each tempFile in this->files:
{
if tempFile == file
{
this->files.erase(…);
break;
}
}
}
countSize()
 loop through vector<File*> files,
 sum the size of each element.
int Folder::countSize()
{
int totalSize = 0;
for each file in files:
totalSize += file->getSize();
return totalSize;
}
Main File
Create two vectors
vector<Folder*> folders;
vector<File*> files;
Createfolder
if (operationType == "Createfolder")
{
string folderName;
cin >> folderName;
folders.push_back(new Folder(folderName));
}
Createfil
e
 File *newFile = new File(…);
 Loop through existing folders
-Find the desired folder
-Add file to folder
Don’t forget to put the file in the folder!
Deletefile
 Loop though existing files
-Find the file
-Loop through existing folders
-Find the desired folder
-Remove file from folder
-Delete the file.
Don’t forget to delete the file in the folder!
Movefile
To Move file A from B to C:
Delete file A from C,
Create file A in B.
Find Largest
 Init largestSize = -1
 Loop through all the folders
-if countSize() > largestSize
Common Errors
1. Constructor
- Incorrect:
Folder(string foldername) {
foldername = foldername;
}
- Correct:
Folder(string foldername) {
this->foldername = foldername;
}
- Correct:
Folder(string _foldername) {
foldername = _foldername;
}
2. Accessor
When the method or attribute is private, you can’t use it in other classes. For
example:
In Folder.cpp, we have private: name; in the main program, folder->name
will not work. You can use the getter method folder->getName(); since
getName() is public.
3. Iterator
When using iterator:
Incorrect: *folder->getSize()
Correct: (*folder)->getSize()
5. Accessing Method
method like getName should be accessed using getName() with the parentheses
case matters.
6. Case Sensitivity
"FindLargest" is different from "Findlargest".