Final Exam of Introduction to Computer Science
NCNU CSIE

Date: January 9th, 2008
Time: 13:10-15:00
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 to_upper(char* str)
   {
   	int i = 0, j = 0;
   	while (*(str + j) != '\0')
   	{
   		if (*(str + j) == ' ')
   			j++;
   		else
   			*(str + i++) = (*(str + j++)   & 0xDF );		
   	}
   	*(str + i) = *(str + j);
   	return;
   }
   
   int main(void)
   {
   	char message[] = "Time and tide wait for no man";
   	to_upper(message);
   	cout << message << endl;
   }
   

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

   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
   	int i, sum;
   	for (i=10, sum=0; i>5; sum+= --i)
   	    cout << "i = " << i << endl; 
               cout << "sum = " << sum << endl;
   }
   

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 = 5555;	
   	int i = (s >> 5) & ~(~0 << 4);
   	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)
   {
   	for (int i=1; i<=100; i++)
   		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;
   	*pvector = *pvector + 1;
   	*pvector + 1 = *pvector + 2;
   	*pvector + 2 = *pvector + 3;
   
   	for (int i=0; i<5; i++)
   		cout << vector[i] << endl;
   }
   

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

   #include <iostream>
   
   int main()
   {
   	for (int i = 1; i < 6; i++) 
   	{
   		if (i==3)
   			break;
   		std::cout << i << std::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)
   {
   	char value = 11, 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::endl;
    using std::cout;
    
    #define WIDTH	15
    
    int main()
    {
        const int n = 10;  	//表n!
        int x[WIDTH] = { 0 } ; //使用array儲存n!的數值	
        int i,j; 		//迴圈用
        int k = 0;  	//儲存第幾個數開始不為0
    
        cout << n << "! = ";
    
        x[WIDTH-1]=1;   //1!=1
    
        for(j=2;j<=n;j++)
        {
    	for (i=WIDTH-1; i>=0; i--)
    	    x[i]=x[i]*j;          
            for (i=WIDTH-1; i>=0; i--)	
    	    if(x[i] >= 10)
    	    {
      		x[i-1]+=x[i]/10;
                    x[i] %= 10;
                }    
        }	
    	
    
        for(i=k;i<WIDTH;i++)
    	cout << x[i];
        cout << endl;                               
    }

11. 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(1, 2,  , 4) << endl;
    }
    
    int sum(int x1, int x2, int x3, int x4)
    {
        return x1 + x2 + x3 + x4;
    }