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Arrays
1 , i^2 ,..,in)
elements.
for I in 1 loop
for I in 1 loop for J in 1 .. N loop Put (B(I,J)); end loop; end loop;
Records
design a record
declare record types and variables
use a record
• Access elements using Indices
- Single Dimension arrays A(I)
- Two dimensional arrays A(I,J)
- N dimensional array A(i
• Loops can be used to access control to
.. N
Get (A(I));
end loop
.. M
To use records we need to know:
- How to
- How to
- How to
1. Designing Records
- identify the items of data that are relevant
data structure diagram to show the relevant information names for the overall structure, and for the individual fields
data types of the fields
Example1 Fitness club
name : names;
phone : phones;
sex : sexes;
age : ages;
weight : weights;
name phone sex age weight
persons
• To design a record:
in this application
-- string sub-type
-- string sub-type
-- enumerated type
-- integer sub-range
-- float sub-type
3. Using records
assignment, parameter, comparison,
etc) just use its name
record_name.field_name
- average_male.weight average_female.name
3. Using records
another of identical type
a single operation. You must read each field separately.
• To refer to an entire record variable (for
• To refer to a field of a record, use
• Assignment
- You can assign one record variable to
- that_person := this_person;
• Input
- You cannot read an entire record variable in
- To input a record variable use a procedure:
- Prompt for and get each field in turn
CQ 1
My_Second_Record
3. Using records
in a single operation. You must display each field separately.
procedure:
1. My_First_Record contains contents of
2. Program will not compile
3. Program gives a run-time error
4. Don’t know
• Output
- You cannot display an entire record variable
- To display a record variable use a
- Describe and display each field in turn
Hierarchical records
any
type, including another record
phone weight
age sex
persons
name title
fname
sname
text_io
line?
• The components of a record can be
• Text_IO
- Page line character
- set_col : go to nominated column in output file
- new_line: go to next line of output
- set_line: go to nominated line in output file
- new_page: go to next page of output
- skip_line: go to start of next line in input
- skip_page: go to start of next page of inputs
- page: what page number are we up to in the file?
- line: what line number are we up to on the page?
- col: what character position are we up to on the
example
SET_COL (30);
PUT ("Student Results Report"); SET_LINE (4); SET_COL ( 5); PUT ("Student name"); SET_COL (35); PUT ("Assignments"); SET_COL (50); PUT ("Exams"); SET_COL (65); PUT ("Average"); SET_LINE (6);
Line length
reached
– SET_LINE_LENGTH (30);
for i in 1 .. 20 loop PUT (i**2, width => 5); ; (^) ' 1 4 9 16 25 36' ‘ 49 64 81 100 121 144' ' 169 196 225 256 289 324' ' 361 400'
• SET_LINE (2);
• For output files
- set_line_length for lines
- set_page_length for pages
• set_line_length
- EOL generated automatically when limit
- Default is 0
end loop
reset
procedure:
open (filevar, in_file, filename); --code to read from the file reset (filevar); --code to read the file all over again close (filevar);
File position functions
• if END_OF_PAGE (infile) then …
while not END_OF_FILE loop …
Need to process a file twice. RESET
Go back to beginning (optionally) change mode File must be open already
-- read file twice
• END_OF_FILE
- Next character is EOF
- Next character is combination of EOL, EOP, EOF
• END_OF_LINE
- Next character is EOL or EOF
• END_OF_PAGE
- Next character is combination of EOL and EOP
- Next character is EOF
Example2 Priority Queue
done efficiently.
Q 5 -3 0 5 12 17?????
0 1 2 3 4 5 6 7 … N
Q
• Data structure that stores items so that
retrieval of ‘highest priority’ item can be
• Highest priority have lower values
• Operations: PUT, GET, EMPTY
Free
