Computer Science 2610

Spring 2000

Quiz 4

1. Write a function called numvowels that takes a null-terminated string as a parameter and returns the number of vowels in the string. Assume that function isvowel is available, where isvowel(c) is true when character c is a vowel. For example, numvowels(“rabbit”) = 2.

2. Suppose that array an array called mouse has been created, and is declared as follows.

char mouse[30];

Suppose that a null-terminated string has been put in array mouse. Using the function numvowels, you would like to set integer variable v to the number of vowels in the string that is stored in array mouse. Which of the following statements will do the job?

(a) v = numvowels(“mouse”);

(b) v = numvowels(mouse[]);

(c) v = numvowels(mouse[30]);

(d) v = numvowels(mouse);

3. To within a constant factor (that is, in terms of proportionality) how long does it take to do a binary search on an array of size n?

(a) log₂(n)

(b) n

(c) n log₂(n)

(d) n²

4. With an error of no more than 1, what is log(256)?

(a) 4

(b) 6

(c) 8

(d) 10

5. To within a constant factor, how long does the exchange sort algorithm take to sort an array of n items?

(a) log(n)

(b) n

(c) n log(n)

(d) n

6. Which of the following is a C++ standard library function that finds the length of a null-terminated string?

(a) lenstr

(b) strlen

(c) length

(d) stringlen

7. Suppose that T is a two-dimensional array of integers, defined by

int T[10][20];

You would like to select the member of T that is in the upper left-hand corner. (That is, it is in the first column and the first row of the array.)

Which of the following expressions returns that value?

(a) T[0,0]

(b) T[0][0]

(c) T[1,1]

(d) T[1][1]