1. Lecture 13 Midterm overview When you know a thing, to hold that you know it, and when you do not know a thing, to allow that you do not know it: this is knowledge Conficus, Analects

2. Problem 1 (10 points) Describe in one sentence the difference between each of the following: 1) write and writeln write prints enclosed expression and leaves the cursor on the same line, while writeln places cursor to the beginning of the next line (via CL/CR). 2) integer and real An integer variables in Pascal represent whole numbers from mathematics with system dependent bounded range, while real variables in Pascal represent decimal numbers from mathematics with system depended bounded range. 3)chr and ord chr function returns a character given an ASCII code, while ord function returns an ASCII code of a given character. 4) writeln( ‘Hello’ ) and writeln( ‘’’Hello’’’ ) First one prints Hello, second prints ‘Hello’. e) Mr. Pascal and Mr. Wirth Pascal was a French mathematician after whom Wirth named the language we are studding

3. Problem 2 (10 points) What is the purpose of each of the following menu items in TP a)Run Executes the program b) Compile Checks the program for errors and converts to machine codes 3)Step over Execute current line of code 4)Add watch Start observing a variable 5)Add breakpoint Mark a line on which the execution of program should pause.

5. Problem 4 (5 points) Find as many mistakes as you can in the following program Progrm My Big Mistake Begin; Readln( iMyInt ); iAnswer := iAnswer / iMyInt; writeline( ‘Answer is ‘, ‘iAnswer’ ); enD Mistakes: 1) Progrm should be spelled Program 2) No spaces in the program name are allowed 3) Missing semicolon after program name 4) Shouldn't have semicolon after begin 5) Need to declare variables 6) writeline should be spelled writeln 7) in the writeln, the iAnswer variable shouldn't be enclosed in quotes 8) There should be a period after enD

6. Problem 5 part a) What would be printed by each of the following programs? PROGRAM TRICKY1; VAR one, two, count : integer; BEGIN one := 10; two := 0; for count := 1 to 2 do BEGIN two := two + one; for one := 1 to 2 do; END writeln( two ); END Result(s) 12 One Two Count init 10 0 for count := 1 to 2 do (I) 1 two := two + one 10 for one := 1 to 2 do (I)1 for one := 1 to 2 do (II)2 for count := 1 to 2 do (II) 2 two := two + one 12 for one := 1 to 2 do (I)1 for one := 1 to 2 do (II)2 writeln(two)produces 12

7. Problem 5 part b) PROGRAM Tricky2; VAR count1, count2 : integer; BEGIN FOR count1 := 1 TO 10 DO FOR count2 := 1 TO count1 DO BEGIN writeln( count1 ); count1 := count2 * 10; END; END. Result(s) 1 count1 count2 for count1 := 1 TO 10 do (I) 1 for count2 := 1 TO count1 do (I)1 (note really count2 :=1 to 1) writeln( count1 ); produces 1 count1 := count2 * 10; 10 (inner loop exits) count1 is 10 so outer loop exits as well

8. Problem 6 (5 points) How many times will each of the following loops be executed? LoopNumber of times a) FOR I:=1 TO 101 DO101 b) FOR I:= ‘a’ TO ‘c’ DO3 c) FOR I:= ‘a’ TO ‘z’ DO26 d) FOR I:= 1 DOWNTO 100 DO0 e) FOR I:= ‘z’ DOWNTO ‘z’ DO1

9. Problem 7 (10 Points) Factorial of a number N (written as N!) is defined as a product of all numbers starting from 1 up to N. That is, N! = 1*2*3*…*(N-2)*(N-1)*N. Write a Pascal program, which reads in a positive integer and outputs the value of N! Program Factorial; var iNumber, iFactorial, iLoopCount : integer; begin writeln( ‘Please enter a positive integer: ‘ ); readln( iNumber ); iFactorial := 1; for iLoopCount := 1 to iNumber do begin iFactorial := iFactorial * iLoopCount; end; writeln( iNumber,’! = ‘, iFactorial ); end.

10. Problem 8 (10 points) Write a Pascal program which reads in two positive integers a and b and then determines the remainder and the whole part when a is divided by b. The program should output a = b*c + d, where c is the whole part and d is the remainder. Program AgainDivAndMod; var a, b, c, d : integer; begin writeln( ‘Enter a, b ); readln( a, b ); c := a div b; d := a mod b; writeln( a, ‘ = ‘, b, ‘*’, c, ‘+’, d ); end.

11. Problem 9 (15 points) Write a Pascal program (utilizing for-loop), that prints every letter of the alphabet and its ‘opposite’. That is, the first few output lines should look like this: ‘a’ – ‘z’ ‘b’ – ‘y’ ‘c’ – ‘x’ etc. PROGRAM OppositeLetter; VAR c1 : char; BEGIN FOR c1 := 'a' TO 'z' DO BEGIN writeln( c1, ' - ', chr( ord( 'z' ) - ord( c1 ) + ord ( 'a' ) ) ); END; END.

12. Problem 10 (15 points) Write a Pascal program, which prints out formatted multiplication table. The table’s rows and columns should run from 1 to 9. Make sure that your table is formatted well. Use loops to do this problem. PROGRAM MultiplicationTable; VAR iLoopCount1, iLoopCount2 : integer; BEGIN { Column headings } write( ' ' ); for iLoopCount1 :=1 to 9 do begin write( iLoopCount1:4 ); end; writeln; for iLoopCount1 := 1 to 9 do begin { Row heading } write( iLoopCount1 ); for iLoopCount2 := 1 to 9 do begin { The value at iLoopCount1 column and iLoopCount2 row } write( (iLoopCount1*iLoopCount2):4 ); end; writeln; end; end.

13. Home work Start reading chapter 6 ( Sections 1,2 )