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CS215 - Lec 5 record organization

Date post: 02-Jun-2015
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Reading/writing collection of records
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Page 1: CS215 - Lec 5  record organization
Page 2: CS215 - Lec 5  record organization

� List different methods for record organization.

� Continue with the company class;

� Use fixed length of bytes ,

� Use fixed number of fields

� Use length indicator,

� Use delimiter,

� Use index.

Dr. Hussien M. Sharaf2

Page 3: CS215 - Lec 5  record organization

Dr. Hussien M. Sharaf3

Fixed length of

bytesVariable length

Length indicator

Record delimiter

Record index

Fixed number of

fields

Page 4: CS215 - Lec 5  record organization

� A fixed length record file is one in which each record contains the same number of bytes.

� The length must be the max expected length.

� Problems:

1. The estimation of max length.

2. The choice of a character to fill the remaining space.

3. Not readable to human eye.

4. Waste of space.

Dr. Hussien M. Sharaf4

Record 3 Record 4Record 1 Record 2

200 bytes 200 bytes200 bytes 200 bytes

Page 5: CS215 - Lec 5  record organization

� A fixed number of fields where each field can be of variable size.

� The count must be the max expected count.

� Problems:

1. The estimation of max count.

2. Not readable to human eye.

3. Waste of space in case of an empty field.

Dr. Hussien M. Sharaf5

Record 3 Record 4Record 1 Record 2

180 bytes 190 bytes210 bytes 250 bytes

6 fields 6 fields6 fields 6 fields

Page 6: CS215 - Lec 5  record organization

� To choose a special character that will not appear within a record and then insert that after each record.

Dr. Hussien M. Sharaf6

3. Record Delimiter

� Problems:

1. The choice of a delimiter character that does not get in the way of processing (ex. White space is not a good choice cause the field may contain spaces within it like “address fields” same for @).

Name EmailID Course

Name EmailID Course

Record1

Record2

\n

\n

Page 7: CS215 - Lec 5  record organization

Dr. Hussien M. Sharaf7

4. Length indicator

And

5. Index

will be continued at next

lecture

Page 8: CS215 - Lec 5  record organization

1. Start by determining Output.

2. List the inputs.

3. Think about processing.

Page 9: CS215 - Lec 5  record organization

� Continue using the CompanyInfo class:

[A] Write a method that takes in ostream and writes to it a company record whose fields have Keyword = Value

� Write a driver to use this class based on the template Menu.

Dr. Hussien M. Sharaf9

Page 10: CS215 - Lec 5  record organization

� Continue using the CompanyInfo class:

[B] Write a method that takes in istream and reads from it a company record whose fields have Keyword = Value

� Write a driver to use this class based on the template Menu.

Dr. Hussien M. Sharaf10

Page 11: CS215 - Lec 5  record organization

� Next week is the deadline.

� No excuses.

� Don’t wait until last day.

� I can help you to the highest limit within the next 3 days.

Dr. Hussien M. Sharaf11

Page 12: CS215 - Lec 5  record organization

1. Delete the “bin” and “obj” folders.

2. Compress the solution folder using winrar.

3. Rename the compressed file as follows:

StudentName_ID_LecExcercise.rar

4. Email to: [email protected] with your ID in the subject.

Dr. Hussien M. Sharaf 12

Page 13: CS215 - Lec 5  record organization

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