Description
1. Consider the following program which should obviously print Match.
#include <iostream>
#include <cmath>
using namespace std;
#define sqr(x) ((x) * (x))
int main() {
double a = 4.0*atan(1.0); // pi
double b = sqrt(a); // square-root of pi
if (a == sqr(b)) // pi is equal to
// square of square-root of pi?
cout << "Match" << endl;
else
cout << "Mis-Match" << endl;
return 0; }
However, on Visual C++ 64-bit compiler, it prints Mis-Match. Identify the bug and fix it. [1 + 1 = 2]
Write an appropriate guideline to avoid such bugs and improve the quality of the code. [1]
2. What is the output of the following program? [1] #include <iostream>
using namespace std;
int main() {
int *p = new int(5);
if (p = 0)
cout << "No Value" << endl;
else
cout << *p << endl;
return 0; }
Is it what the developer intended? If yes, justify the thoughts of the de- veloper. If no, find the bug in the program and fix it. [1]
Write an appropriate guideline to avoid such bugs and improve the quality
of the code.
1
[1]
3. Consider the following program:
#include <iostream> using namespace std;
int rem(int n, int r) {
return n % r;
}
int main() {
int n = 15, r = 0; // Line 1
- // Â intn,r;//Line2
- // Â cin>>n>>r;//Line3
if (r == 0 || rem(n, r)) cout << "True" << endl;else cout << "False" << endl;if (rem(n, r) || r == 0) cout << "True" << endl;else cout << "False" << endl;return 0; }
While using Visual C++ 64-bit compiler, the output is as follows:
Build Type
Output
Debug (Un-optimized) True
Un-handled Floating Point Exception
Release (Optimized) True True
Now let us comment Line 1 and un-comment Line 2 & Line 3. The output changes to the following while we input 15 for n and 0 for r (as was initialized in Line 1:
Build Type
Output
Debug (Un-optimized) True
Un-handled Floating Point Exception
Release (Optimized) True
Un-handled Floating Point Exception
Explain the behavior in both cases, especially justifying the difference due to changing Line 1 to Line 2 & Line 3 and providing the same input.
[2 + 2 = 4]
Write an appropriate guideline to avoid such bugs and improve the quality of the code. [1]
4. Consider the following program having 6 functions – each being a slight variant of the other. State the behavior (like compilation error, wrong output, run-time exception, correct output – showing the output, unpre- dictable behavior, etc.) of each function with proper justification (refer to specific lines in a function as you may need) of the behaviour as stated. You may compare the functions also from the perspectives of the quality of the code. Make a table in the following format in your submission sheet
and fill up accordingly.
[0.3 * 6 = 3]
2
Function Name
f1() f2() ... f6()
Behaviour
Justification & Comments
Finally, based on the observations above, formulate guidelines to maintain a good quality of code. [2]
#include <iostream> #include <cstring> using namespace std;
void f1() {
char * str = "Bat";
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = "Rat";
cout << str << endl;
cout << endl;
}
void f2() {
const char * str = "Bat";
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = "Rat";
cout << str << endl;
cout << endl;
}
void f3() {
char * const str = "Bat";
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = "Rat";
cout << str << endl;
cout << endl;
}
void f4() {
char * str = strdup("Bat");
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = strdup("Rat");
cout << str << endl;
cout << endl;
}
void f5() {
const char * str = strdup("Bat");
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = strdup("Rat");
cout << str << endl;
cout << endl;
}
3
void f6() {
char * const str = strdup("Bat");
cout << str << endl;
str[0] = ’C’;
cout << str << endl;
str = strdup("Rat");
cout << str << endl;
cout << endl;
}
int main() {
f1();
f2();
f3();
f4();
f5();
f(6);
return 0; }
5. Consider the following program where 24 lines have been marked. State the behavior (like compilation error, wrong output, run-time exception, correct output – showing the output, unpredictable behavior, etc.) of each line with proper justification (refer to specific lines in a function as you may need) of the behaviour as stated. Make a table in the following for- mat in your submission sheet and fill up accordingly.
Function Name
Line 01 Line 02 ... Line 24
Behaviour
[0.5 * 24 = 12]
Justification & Comments
Finally, based on the observations above, formulate guidelines to maintain a good quality of code. [2]
#include <iostream> #include <cmath> using namespace std;
int e(int x) {
cout << "x = " << x << " &x = " << &x << endl;
return (x);
}
int f(int &x) {
cout << "x = " << x << " &x = " << &x << endl;
return (x);
}
int& g(int x) {
cout << "x = " << x << " &x = " << &x << endl;
return (x); }
int& h(int &x) {
cout << "x = " << x << " &x = " << &x << endl;
return (x);
}
4
int main() {
int a = 10;
cout << "a = " << a << " &a = " << &a << endl;
int& rvv = e(a); // Line 01
int& rrv = f(a); // Line 02
int& rvr = g(a); // Line 03
int& rrr = h(a); // Line 04
cout << "rvv = " << rvv << " &rvv = " << &rvv << endl; // Line 05
cout << "rrv = " << rrv << " &rrv = " << &rrv << endl; // Line 06
cout << "rvr = " << rvr << " &rvr = " << &rvr << endl; // Line 07
cout << "rrr = " << rrr << " &rrr = " << &rrr << endl; // Line 08
const int& rvvc = e(a); // Line 09
const int& rrvc = f(a); // Line 10
const int& rvrc = g(a); // Line 11
const int& rrrc = h(a); // Line 12
cout << "rvvc = " << rvvc << " &rvvc = " << &rvvc << endl; // Line 13
cout << "rrvc = " << rrvc << " &rrvc = " << &rrvc << endl; // Line 14
cout << "rvrc = " << rvrc << " &rvrc = " << &rvrc << endl; // Line 15
cout << "rrrc = " << rrrc << " &rrrc = " << &rrrc << endl; // Line 16
e(a) = 1; // Line 17
cout << "a = " << a << " &a = " << &a << endl; // Line 18
f(a) = 2; // Line 19
cout << "a = " << a << " &a = " << &a << endl; // Line 20
g(a) = 3; // Line 21
cout << "a = " << a << " &a = " << &a << endl; // Line 22
h(a) = 4; // Line 23
cout << "a = " << a << " &a = " << &a << endl; // Line 24
return 0; }
5
