� Storing collection of records.

� Reading collection of records.

� Writing collection of records.

� Buffering Algorithm.

Dr. Hussien M.

Sharaf2

� Company info class only represents single record.

� A collection of records needs to be stored into a dynamic array.

� The collection of records can be encapsulated into a class that maps to a file.

Dr. Hussien M.

Sharaf3

Company1

Company2

…..

Company N

Dr. Hussien M.

Sharaf4

CompanyInfoCollection

StructureRecord 3 Record 4Record 1 Record 2210 250 180 190

1. Store collection of records in a dynamic array

2. Store file full path name.

3. Store and manage the indexing of records.

Dr. Hussien M.

Sharaf5

CompanyInfoCollection

FunctionalitiesRecord 3 Record 4Record 1 Record 2210 250 180 190

1. Responsible for opening and closing of the file stream.

2. Calling read or write of companyInfo without knowing the details of read/write single line.

3. Manage the buffering of records while reading or writing.

4. Count the number of records in a file.

Dr. Hussien M.

Sharaf6

Algorithm#1 Writing collection of

recordsRecord 3 Record 4Record 1 Record 2210 250 180 190

� While (len(Buffer) < bufferingSize)

� {

� companyInfo[i].writeIntoStream( stringStream)

� stringStream<<recordDelimiter

� i++

� }

� Stringstream>>Buffer

� FileStream.write(Buffer)

Dr. Hussien M.

Sharaf7

Algorithm#2 Reading collection

of records

Record 3 Record 4Record 1 Record 2210 250 180 190

� FileStream.read(Buffer, BufferingSize+1)

� Stringstream<<Buffer;

� While (! Stringstream.EOF)

� {

� companyInfo[i].ReadFromStream(Stringstream)

� i++

� }

1. Read x MB into memory buffer (i.e. char array).

2. Make sure to stop reading at the end of a record. How can this be done?

3. Put the buffered data into a string stream.

Dr. Hussien M.

Sharaf8

4. Pass the string stream to an instance of companyInfo which extracts fields.

5. Add the new companyInfo to the array of records.

6. Manage the index by adding an entry with the correct offset.

7. Repeat steps 1-6 until EOF

Dr. Hussien M.

Sharaf9

Dr. Hussien M.

Sharaf10

� Store the byte offset of each record into a list stored in another file.

Dr. Hussien M.

Sharaf11

Remember Indexing

� Problems:

1. Two files are used: one for the data and another for

CompanyName offset

IBM 0Record1

\n

\n

Google 211Record2 \n

Microsoft 462Record3 \n

ITE 643Record4 \n

Dr. Hussien M.

Sharaf12

class CompanyInfoCollection

{

private:

vector<CompanyInfo> Records;

RecordIndex recordIndexes;

public:

//read delimited fields

bool WriteDelimRecords(ostream& ,char);

//read delimited fields

bool readDelimRecords(istream&);

};

Dr. Hussien M.

Sharaf13

Read/write from

streamBuffer

Single companyInfo

RecordsCollection

File stream

Read/write from

streamBuffer

Single companyInfo

Records Indexes

Record 2211 Record 3462

�Continue using the CompanyInfo program:

1) Where would you put the following functionalities:a. Read the multiple records into a buffer.b. Split a single record into fields.c. Append a single record into a collection of

records.d. Search for a record given a company

name.

Dr. Hussien M.

Sharaf14

�Continue using the CompanyInfo program:

2) Implement Algorithm#1 into the CompanyInfo program.

3) Implement Algorithm#2 into the CompanyInfo program.

Dr. Hussien M.

Sharaf15