Introduction to Computers -Final exam- 授課教授：李錫智

Q1 Write a function named Reverse that takes a string as input and returns a copy of that string in reverse order. For example, the function call Reverse("apple") should return the string "elppa".

Solution of Q1 Ans: function Reverse(str) { var len,restr; len=str.length; restr=""; i=len-1; while(i!=-1) { restr=restr+str.charAt(i); i=i-1; }

Q2 Consider the following program : function string(string){ str = string; i = str.search(/[aeiou]/); while(i != -1){ str = str.substring(0,i) + '*' + str.substring(i+1,str.length); i = str.search(/[aeiou]/); } return str; } What will be returned for the function call string('Hello world')?

Solution of Q2 Ans: H*ll* w*rld

Q3 Write a function named Maximum that takes an array of numbers as input and return the biggest value in the array. For example, the call Maximum([2, 28, 33, 12, 5, 17, 8]) should return 33.

Solution of Q3

Q4 Suppose you are given the following segment of program: Phrase = “George Bush, USA\n”+ “Leonardo da Vinci, Italy\n”+ “William Shakespeare, England\n”; Spilt_1 = Phrase.split(“, “); Spilt_2 = Phrase.split(/[,\n]+/); [5] What is the value of Split_1? [5] What is the value of Split_2?

Solution of Q4 Ans: Split_1 = ["George Bush", "USA\nLeonardo da Vinci", "Italy\nWilliam Shakespeare", "England\n"] ; Split_2 = ["George Bush", "USA", "Leonardo da Vinci", "Italy", "William Shakespeare", "England"];

Q5 Please using the NOT, AND, and OR gates, draw a circuit that will output 0 while both inputs are 0 or 1. That is, suppose A and B are the two inputs and C is the output, then C=0 if and only if (A=0 and B=0) or (A=1 and B=1).

Solution of Q4 ABC

Q6 Consider the following program: What will be returned for the function call Cipher('Bronze')? function Cipher(str) { var coded, ch, index, key, i; alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; coded = ' '; key = 4; str = str.toUpperCase(); i = 0; while(i < str.length) { ch = str.charAt(i); index = alphabet.search(ch); if (index != -1) { if ( (index+key) < alphabet.length) { coded = coded + alphabet.charAt(index+key); }else{ coded = coded + alphabet.charAt(index+key-alphabet.length); } }else{ coded = coded + ch; } i = i + 1; } return coded; }

Solution of Q6 Ans: FVSRDI Offset 4 characters.

Q7 Suppose you are given an array of numbers, A. (a) [10] Please write a function taking A and returning an array B which records the number of times each element appearing in A. For example, suppose A=[15,25,35,45,35,35,25]. Then B=[1,2,3,1,3,3,2]. (b) [10] Please write a function taking A and returning the element in A which appears most frequently in A. For example, for the above example, 35 will be returned.

Solution of Q7

Q8 Please design a Web page that asks the user to enter his/her name and age in a phrase separated by a colon, e.g., John :36. When the user clicks a button, the webpage will show the name and say the user is an adult or a child, e.g., John is an adult. Note that a person is an adult if his/her age is equal to or greater than 20.

Solution of Q8

Q9 Consider the following circuit. A, B, and C are inputs. P and Q are outputs. Please list the input- output relationship in a truth table.

Solution of Q9 ABCQP

Q10 Please write a function to check whether a given string is a mirror-string. A string A is a mirror-string if and only if A satisfies one of the following conditions: A is a concatenation of B and C, i.e., A=BC, where B and C are strings and C is the reverse of B. For example, “abccba” is a mirror-string. A is a concatenation of B, t, and C, i.e., A=BtC, where B and C are strings, t is a character, and C is the reverse of B. For example, “abcycba” is a mirror-string.

Solution of Q10 Ans : function IsP(string) { var stripped, front, back; stripped = string; front = 0; back = stripped.length - 1; while (front < back) { if (stripped.charAt(front) != stripped.charAt(back)) { return false; } front = front + 1; back = back - 1; } return true; }

The end of the final Exam