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(a) What are the
values I and J in the following program segment? |
[2] |
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Values of
I and J: |
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I = 6 |
[1] |
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J = 7 |
[1] |
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(b) What does the
following program print? |
[4] |
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Award one mark
for each of numbers in the output below. Do not deduct marks if the answers do not include
the accompanying text such as val =.. one =... |
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val = 3
one = 2 |
[2] |
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val = 2
two =2 |
[2] |
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(c) Define
implementations of the following library functions: |
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Implementation
of strlen, strncpy, and strrev: |
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int strlen (char *str); |
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void strncpy (char *dst, char
*src, int n); |
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void strrev (char *dst, char
*src);
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(i) Where strlen, returns the
number of characters in the string stc. |
[4] |
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Definition
of strlen: |
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 |
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and the
following marking scheme should be used: |
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one mark for iterating
down the string str until a null character is found (may be a while or for-loop). |
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one mark for incrementing
src so that the loop iterates down the string. |
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one mark for incrementing
a temporary counter that holds the number of characters encountered during traversing the
string. |
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one mark for returning the
value of the temporary counter. |
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no marks should be
deducted for trivial syntactic errors. |
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[4
marks] |
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(ii) Where strncpy, copies at most
n characters of the string stc into dst. You can assume that dst is a character string
with at least n elements. |
[5] |
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Definition
of strncpy: |
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 |
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and the
following marking scheme should be used: |
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defining an iteration
statement (may be a while or for-loop), such that the loop is terminated when either a
null character is seen, |
[1] |
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or n characters have been
copied. |
[1] |
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During the i th
iteration of the loop, the i th character from src needs to be copies into dst. |
[1] |
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During each iteration of
the loop, n needs to be decremented. |
[1] |
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After the characters from
src have been copied into dst, dst has to be null terminated. |
[1] |
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no marks should be
deducted for trivial syntactic errors. |
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[5
marks] |
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(iii) Where strrev, copies a
reversed version of src into dst. Note: you may use strlen in your definition. |
[5] |
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Definition
of strrev: |
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 |
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and the
following marking scheme should be used: |
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one mark for calculating
len, the length of src |
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one mark defining an
iteration statement (may be a for or while loop), that performs len iterations. |
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during iteration i, two
marks should be awarded for assigning dst[i] = src[len - i-1]. Only one mark should be
awarded if the assignment dst[i] = src[len - i] is used. |
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one mark for null
terminating dst. |
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no marks should be
deducted for trivial syntactic errors. |
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[5
marks] |
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