Final Exam of Introduction to Computer Science
NCNU CSIE

Date: March 6th, 2008
Time: 08:10-11:00 
Open book; turn off computer & mobile phone

1. What will be the output of the following program?

   #include <iostream>
   using std::cout;
   using std::endl;
   
   void echo(char* s)
   {
   	int i = 0;
   	while (s[i++] != '\0')	
   		cout << s[i];
   	cout << endl;
   }
   
   void main()
   {
   	echo("CAD");
   }
   

2. Distinguish the meaning of "arguments" and "parameters" in calling a function. Try to use an example to illustrate your explanation, if that helps.
3. Check whether the following program has any mistake. If yes, point out the mistakes and correct them; if no, predict the output of the program.

   #include <iostream>
   void exchange(int& a, int& b)
   { a ^= b;
     b ^= a;
     a ^= b;
   }
   
   int main(void)
   { int x[] = { 1, 3, 5, 7, 2, 4, 6 };
     const int K = sizeof x / sizeof x[0] - 1;
     int i, j;
     for (i=0; i<K-1; i++)
   	  for (j=i+1; j<K; j++)
   		  if (x[i] < x[j])
   			  exchange(x[i], x[j]);
     for (i=0; i<K; i++)
   	  std::cout << x[i] << " ";
     std::cout << std::endl;
   }
   

4. Show the output of the following program.
   
   #include <iostream>
   int main() // Understanding bitwise operators.
   {
   	unsigned s = 3333;	
   	int i = (s >> 3) & ~(~0 << 3);
   	std::cout << i;
   }
   

5. Check whether the following program has any mistake. If yes, point out the mistakes and correct them; if no, predict the output of the program.

   #include <iostream>
   
   int sum = 0;
   
   void print_sum()
   {
   	std::cout << sum << std::endl;
   }
   
   int main(void)
   {
   	int i;
   	for (i=1; ++i<=100; i++)
   		if (i>90) break;
   		sum += i;
   	print_sum();
   }
   

6. Consider the following program. What will the program output?

   #include <iostream>
   
   using std::cout;
   using
       std::endl;
   
   int main() 
   {
   	int value[5] = { 5 };
   	int i = 0;
   
   	for (i=0; i<5; i += 2)
   		value[i] += i;
   
   	cout << value[0] << "\t" << value[2] << "\t" << value[3] << endl;
   }
   

7. Check whether the following program has any mistake. If yes, point out the mistakes and correct them; if no, predict the output of the program.

   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   int main()
   {
   	int vector[] = {1, 2, 3, 4, 5};
   	int* pvector = vector;
   	int* p2 = &vector[2];
       
       	cout << static_cast<int>(p2 - pvector) << endl;	
       	cout << sizeof(pvector) << endl;
       	cout << sizeof(vector) << endl;
   }
   

8. What will be the output of the following program?

   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   int gcd(int a, int b)	// Greatest Common Divisor 
   {
   	if (b > 0)	
   		return gcd(b, a % b); 
   	else 
   		return a;
   }
   
   void main()
   {
   	cout << gcd(12, 8) << endl;
   	cout << gcd(5, 97) << endl;
   }

9. Check whether the following program has any mistake. If yes, point out the mistakes and correct them; if no, predict the output of the program.

   // Ex3_13.cpp
   // Demonstrating nested loops to compute factorials
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main(void)
   {
   	unsigned char value = 12, factorial = 1;
   	for (int i = 2; i<=value; i++)
   	{
   		factorial *= i;
   		cout << "Factorial " << i << " is " << static_cast<int>(factorial);
   		cout << endl;
   	}
   }

10. Check whether the following program has any mistake. If yes, point out the mistakes and correct them; if no, predict the output of the program.
    
    #include <iostream>
    using std::cout;
    using std::endl;
    
    int sum(int x1=1, int x2=2, int x3=3, int x4=4);
    // Supply default values of parameters
    
    int main(void)
    {
        cout << sum(300, 15) << endl;
    }
    
    int sum(int x1, int x2, int x3, int x4)
    {
        return x1 + x2 + x3 + x4;
    }