April 1999
CA208: 'C' PROGRAMMING

QUESTION 5

Total Marks: 20 Marks

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SAMPLE STUDENT'S SOLUTIONS
for Question 5

 
(a) Describe the effect of adding the keyboard static to a local variable in a procedure or function.

 

 [2]
(b) Identify the difference between stack and heap allocated data in C.

 

 [3]
(c) (i) Using a single statement, declare a one-dimensional integer array called digits, and initialise it with the values 10, 20, and 30. [2]
(ii) Using a single statement, declare a two-dimensional integer array of three elements by three elements, called moredigits, and initialise it with the following integer matrix:

(9, 8, 7)(6, 5, 4)(3, 2, 1)

 

 [3]
(iii) Using a single statement, declare a character array called footy, and initialise it with the letters (c, f, e, e, d, n, u, d). The array should be no larger than is necessary to contain these letters.

 

 [2]
(d) The following function is intended to return an array containing the numbers [4, 3, 2, 1]. Explain why the function may not work as intended.

int * fournums() {
   int res[] = {4, 3, 2, 1};
   return res;
}

 

 [2]
(e) Assume the following definition of the function foobar:

int foobar(int xs[], int n) {
   int i;
   for(i=0; (i<n) && (xs[i] < 0); i++) {}
   return ((i>=n)?(-1):i);
}

 
(i) Describe the result of evaluating foobar(xs, 6) when xs is the array

xs[] = {-20, 11, 1, 9, -6, 5}

 

 [1]
(ii) Describe the result of evaluating foobar(xs, 6) when xs is the array

xs[] = {0, 11, 0, -5, 6, 1}

 

 [1]
(iii) Describe the result of evaluating foobar(xs, 6) when xs is the array

xs[] = {20, 11, 1, 5, 6, 1}

 

 [1]
(iv) Describe the effect of foobar(xs, n) when given an arbitrary array xs containing n values. [3]