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<HTML><HEAD><TITLE> Solutions for Problems in MidTerm I </TITLE></HEAD><BODY>------------------------------------PROBLEM #1---------------------------------------------<P>Only a single Pascal statement is required, although the computation could be done with a couple of statements instead. <br><BR><PRE>program problem1;var s1, s2, s3 : string;begin writeln('enter s1, the substring'); readln(s1); writeln('enter s2, the superstring'); readln(s2); s3:=copy(s2, pos(s1,s2), length(s2) - pos(s1,s2) + 1); { <<<< the statement} writeln('s3 = ',s3); readln;end.</PRE><br><br>------------------------------------PROBLEM #2---------------------------------------------<P>The procedure is all that is needed. <BR><BR><PRE>program problem2;var s : string; n : integer;procedure vowelCount (var s: string; var numberOfVowels: integer);var i : integer; chr : string;begin numberOfVowels := 0; i :=i 1; while i <= length(s) do begin chr := copy(s,i,1); if (chr='a') or (chr='e') or (chr='i') or (chr='o') or (chr='u') then numberOfVowels := numberOfVowels + 1; i := i + 1; end;end;begin writeln('enter a string'); readln(s); vowelCount(s,n); writeln('number of vowels is: ',n); readln;end.</PRE><br><br>------------------------------------PROBLEM #3---------------------------------------------<P>The procedure is all that is needed. <BR><BR><PRE>program problem3;type integerArray = array [1..100] of integer;var A : integerArray; n, i : integer;procedure fib(var fibArray: integerArray; var n: integer);var i : integer;begin i := 3; fibArray[1] := 1; { don't worry that n might be less than 2 } fibArray[2] := 1; while i <= n do begin fibArray[i] := fibArray[i-1] + fibArray[i-2]; i := i + 1; end;end;begin writeln('enter an integer'); readln(n); fib(A, n); writeln('fibonacci of ',n,' is: '); i := 1; while i <= n do begin writeln(A[i]); i := i + 1; end; readln;end.</PRE><br><br>------------------------------------PROBLEM #4---------------------------------------------<P>No, not every Pascal program is an algorithm. All Pascal program meet the first fewrequirements because, to a Pascal Machine, Pascal operations are well ordered, unambiguous, and effectively computable. However, not all Pascal programs meet the last constraint. That is,some Pascal programs fail to halt in finite time because they contain an infinite loop,such as the following program: <br><br><PRE>program infiniteLoop;var i : integer;begin i := 1; while i = 1 do writeln('I am looping ... ');end.</PRE><br><br>------------------------------------PROBLEM #5---------------------------------------------<P>Since we have dealt with array in class, we'll use four arrays to store our information: <BR><br><UL><LI><B>title</B> : stringarray<LI><B>artist</B> : stringarray<LI><B>recording_studio</B> : stringarray<LI><B>no_in_stock</B> : integerarray</UL>We also need a variable to keep track of the number of unique CDs in the inventory (to know whento stop the loop. <BR><BR>To print out report a procedure called Print is used.<BR>parameters: title, artist, recording_studio :stringarray, no_in_stock: integerarray, index:integer<BR>Function: Given an index (location), it prints out the contents of all four arrays at that index.<BR><BR>To search, we define a procedure search.<BR>Parameters: item_searched: string; array_searched: stringarray; position : integer;<BR>Function: It goes through the array_searched and gets the position where it finds a match withitem_searched. It then calls Print to output a report and does this for the entire array.<BR><BR>By calling search with different parameters (say title_of_CD, and the array title etc.) we canperform all the three searches required in this case.<br><BR>------------------------------------PROBLEM #6---------------------------------------------<P>A Database Machine can be built "on top of" a Pascal Machine by writing a Pascal program thatruns on the Pascal Nachine and implements the operations of the Database Machine. Theseoperations might include : add-record, delete-record, search-for-record, and so on.<br><br>------------------------------------PROBLEM #7---------------------------------------------<P><PRE>program problem7;type realArray = array [1..100] of real;var Arr : realArray; n: integer; sum, avg : real;begin readArray(Arr, n); sumArray(Arr, n, sum); avg := sum / n ; writeln('average is: ',avg); printArray(A, n);end.</PRE><br><br>------------------------------------PROBLEM #8---------------------------------------------<P><PRE>program problem8;type integerArray = array [1..100] of integer;var Arr : integerArray; n: integer;begin {Initialize the array to zeros} n := 1; while n <= 100 do begin A[n] := 0; n := n + 1; end; {enter integers and count their frequency} writeln('enter an integer between 1 and 100, or -1 to stop'); readln(n); while n <> -1 do begin A[n] := A[n] + 1; writeln('enter an integer between 1 and 100, or -1 to stop'); readln(n); end; {write out the frequency of integers that occurred more than once} n := 1; while n <= 100 do begin if A[n] > 1 then writeln(n, ' occurred ', A[n], ' times.'); n := n + 1; end; readln;end.</PRE><br><br> ------------------------------------PROBLEM #9---------------------------------------------<P>A procedure's formal parameters may have different names than the actual parameters used in a callto the procedure. This is important for making the procedure modular and enabling its reuse. Aprogram may use a procedure without knowing the names of the variables that the procedure uses. Also,the procedure may be used by many programs, each of which calls the procedure with different actual parameters.<br><br>------------------------------------PROBLEM #10---------------------------------------------<P>part a. <BR><BR><PRE><sentence> -> <noun phrase> <verb phrase> | | v v <determiner><noun> <verb><noun phrase> | | | | v v v v the girl chases <determiner><noun> | | v v a ball</PRE>part b. <BR><BR>It is conceivable that a grammar checker could be written using such rules. The grammar checkerwould attempt to generate each sentence written with the word processor. Those sentences thatcan be generated using the rules would be deemed to be correct. Those sentences that could notbe generated with the rules would be deemed incorrect. <BR><BR>However, the set of rules would be very large. A complete set of rules for English has not beendeveloped. <BR><BR></BODY></HTML>⌨️ 快捷键说明
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