STRING Represents group of characters Each character 1 byte CIE, AB304 BOOLEAN Logical Datatype, return true or False Memory Required 1

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1 2.2 Data representation Data types A data type is a method of interpreting a pattern of bits. There are numerous different data types but here explained ones are according to CIE syllabus: Integer Represents whole number Memory Required 2 2,15 bytes REAL Represents number with decimal Memory Required 4 2.5, bytes CHAR Represents single character Memory Required 1 a, E byte STRING Represents group of characters Each character 1 byte CIE, AB304 BOOLEAN Logical Datatype, return true or False Memory Required 1 byte DATE Represents date in different format like MM/DD/YYYY Memory Required 10 bytes 05/11/1995 Select appropriate data types for a problem solution It is important to declare identifier with appropriate data type in order to minimize error while assigning data. It is also important for data manipulation. It is also advantageous to allocate appropriate memory size minimizing wastage of memory. e.g: A database of properties in of Student Enrollment displays, on the screen, a form to allow the user to enter queries. The following details are displayed on the screen: a College logo a space for the name of the Students 2 questions about the Books such as Book Name and Price. a means of going on to the next screen and also a means of returning to the previous one (a) Write suitable data types for the following: Field Name Description Data Type No. of Bytes StuCode Key Field, Unique Registration number of INTEGER 4 FirstName the student First Name of the student STRING 20 LastName Last Name of the student STRING 20 Date of borrowed Arrays Date of Birth DATE 8 Array An array is a data structure, which allows a set of items of identical data type to be stored together using the same identifier name. Arrays are declared in a similar way to standard variables, except that the array size and dimensions are included.

For example, the following declares an array that reserves five locations in memory and labels these as Names : DIM Names(4) As String Name Name of array variable 4 subscript String Datatype Array

2 For example, the following declares an array that reserves five locations in memory and labels these as Names : DIM Names(4) As String Name Name of array variable 4 subscript String Datatype Array can also be declared with lower and upper bound as shown below: DIM Names[0:4] As String Name Name of array variable 0 Lower Bound 4 Upper bound String Datatype The five individual locations are Names(0), Names(1), Names(2), Names(3), Names(4). Each data item is called an element of the array. To reference a particular element a programmer must use the appropriate index. For example, the following statement assigns data to the 5th element: Names(4) = Johal Arrays simplify the processing of similar data. An algorithm for getting five names from the user and storing them in the array Names is shown below: Dim Names[0:4] As String For i=0 TO 4 Input Value Names[i]=Value One dimensional arrays A one dimensional array is a data structure in which the array is declared using a single index and can be visually represented as a list. The following diagram shows the visual representation of the array Names(4): Two dimensional arrays A two dimensional array is a data structure in which the array is declared using two indices and can be visually represented as a table. The following diagram shows the visual representation of an array Students[4,2] or Students[0:4,0:2]

3 Each individual element can be referenced by its row and column indices. For example: Students[0,0] is the data item JONES Students[2,1] is the item M Students[1,2] is the item LAMBOURNE Initializing an array Initializing an array is a procedure in which every value in the array is set with starter values this starting value would typically be for a string array, or 0 for a numeric array. Initialization needs to be done to ensure that the array does not contain results from a previous use, elsewhere in the program. Algorithm for initializing a one dimensional numeric array: DIM TestScores[0:9] As Integer DIM Index As Integer FOR Index = 0 TO 9 TestScores[Index] = 0 NEXT Algorithm for initializing a two dimensional string array: DIM Students[0:4,0:2] As String DIM RowIndex, ColumnIndex As Integer FOR RowIndex = 0 TO 4 FOR ColumnIndex = 0 TO 2 Students[RowIndex,ColumnIndex] = NEXT NEXT Linear search on an array The following pseudo code can be used to search an array to see if an item X exists: 01 DIM Index As Integer 02 DIM Flag As Boolean 03 Index = 0 04 Flag = False 05 Input X 06 REPEAT 07 IF TheArray[Index] = X THEN 08 Output Index 09 Flag = True 10 END IF

4 11 Index = Index UNTIL Flag = True OR Index > Maximum Size Of TheArray Note that the variable Flag (line 04 and 09) is used to indicate when the item has been found and stop the loop repeating unnecessarily (line 12 ends the loop if Flag has been set to True). To complete the search algorithm some lines should be added, after the loop, to detect the times when the item X was not found in the array: 13 IF Flag = False THEN 14 Show Message Item not found 15 END IF Sorting using a bubble sort DECLARE a[1:10]:integer DECLARE temp:integer FOR i=1 TO 10 INPUT a[i] FOR i=1 TO 9 FOR j = 1 TO 9 If a[j] > a[j + 1] temp = a[j] a[j]=a[j + 1] a[j + 1] = temp END IF Files Files are collection of related records in specific format. It is important to search records easily and quickly and also to access records in future as required. File Handling It is programming technique to create file and add/manipulate records in it as required by the user. Few tasks that can be done in file are: Add records in file Display all/selected records from file Search record in file Delete record from file Modify content of record in file Whatever be the task, two major works to be done in file are reading from file and writing in file. Pseudocode for opening a file OPENFILE <filename> FOR <mode> Filename: Name of current file along with path if not in current path Mode: Purpose of opening a file, various purposes are OUPUT/READ/APPEND/WRITE OUTPUT: opens a file in writing mode as a new file, if file is already existing, then it is replaced by new file. APPEND/WRITE: Records are added at the end of file without affecting previous

5 record if already existed READ: opens a file in read only mode. Pointer is at the beginning of file Pseudocode for reading a record from file READFILE <filename>, <string> It read a line of text, as a record, from specified file and stores in string variable READFILE #<filenumber>,<identifier1>,<identifier2>,.,<identifiern> It read a record field by field from specified file and stores each filed of a record in separate variable. Pseudocode for writing record in a file WRITEFILE <filename>, <string> It write a line of text, as a record, to specified file. WRITEFILE #<filenumber>,<identifier1>,<identifier2>,.,<identifiern> It write a record, field by field in specified file where each filed of a record is in separate variable. Pseudocode for closing file CLOSEFILE It close all the opened files CLOSEFILE #<filenum> It close one or more specified, opened file/s. Pseudocode to detect end of file EOF() This function is to test for the end of file and returns result either true or false Example programs of few pseudocode To create file and record as per users choice OPENFILE profile.txt FOR OUTPUT DO INPUT record WRITEFILE profile.txt,record INPUT want to add another record,choice LOOP WHILE choice< Y To display all records OPENFILE profile.txt FOR READ WHILE profile.txt not at EOF() READFILE profile.txt, record DISPLAY record END WHILE

6 To Search and display a record on the basis of code number OPENFILE profile.txt FOR READ INPUT code_num to search Found=0 WHILE profile.txt not at EOF() READFILE profile.txt, record IF code_num=record:code THEN Found=1 END IF END WHILE IF Found=0 Then DISPLAY record not found ELSE DISPLAY record END IF

2.2 Data representation

2.2 Data representation An array is a data structure, which allows a set of items of identical data type to be stored together using the same identifier name. Arrays are declared in a similar way to standard variables, except