it is a storage which is used to store and organize and update the data.It is the way of organizing the data on a computer so that it can be accessed and update effeciently. Data Structure= Organized data + Allowed Operations.
it is a set of values along with set of operations permitted on them.
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A set of data values
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A set of functions specifying the operations permitted on the data.
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A SET Of axioms how these operations work.
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flow chart
terminal-start/end
parlellogram-input/output
rectangle-logic/process
rhombus-decision
Data- it can be defined which are used together to represent a specific data element e.g- name of a student in a class is represented by the data item,say, NAME. Representation of facts, concepts or instructions in formalized manner suitable for communication,interpretation or processing by human or electronic machine. Raw Facts and figures i.e Alphabets-(A-Z),(a-z),digits-(0-9) or special characters(+,-,/,*,<,>,+ etc) Information- It is collection of meaningful data.
Data Item(Field)- A set of characters which are used together to represent a specific data element e.g- name of s student in a class is represented by data item, say NAME Record- it is collection of related data items e.g- a payroll record for employee contains data field such as age, qualification, sex , Basic Pay, DA, HRA, PF etc File(Data File)- It is a collection of logically related records e.g- a payroll file might consist of employee pay records for a company.
EXAMPLE 1 consider the STUDENT FILE
_____________________________________________________________________________________________________________________________________
| SID ! NAME ! MARKS ! SUBJECT |
|____________________________________________________________________________________________________________________________________ ! ! |
| ! ! |
| ! X ! |
| 12001 ! ! ! |
| ! |
| ! ! ENGLISH |
| ! ! 66 |
| ! |
| ! ! ! |
| ! |
| __________________________________________________________________________________________________________________________________ ! \ ! | ! !
| ! Y ! |
| 12100 ! ! 34 ! |
| ! | \ X=X=SECONDARY KEY =NAME 66=66=SECONDARY KEY=SUBJECT ID=PRIMARY KEY
| ! ! ! | /
| ! ! ! MATH ! /
! ! ! ! ! /
| ! ! ! | /
|______________________________________________________________________________________________________________________________________ ! / ! ! | /
| ! 66 | /
| 11209! X ! MATH |
| ! ! |
| _______________________!!!_________________________ |