國立暨南國際大學 113 學年度第二學期小考試卷

1. (10%) Consider the following program. Suppose we compile it with the command "g++ -g q1.cpp -o q1.exe". 
   // q1.cpp
   #include <iostream>
   
   void f2() {
       int x = 30;
       int y = 40;
       int z = 50;
   }
   
   void f1() {
       f2();
       int x = 3;
       int y = 4;
       int z = 5;
   }
   
   int main()
   {
       f1();
       int x = 1000;
       f2();
       return 0;
   }
   
   
   
If we run "gdb q1.exe" with the following commands, what value of x shall we obtain, respectively?

1. break main
   run
   next
   next 
   next
   next
   print x

2. break main
   run
   step
   step
   step 
   step
   print x
   
   

2. (10%) Consider the following program.  Please note that the line number on the left is only shown for your convenience.  They are not part of the code.
   
     1 #include <iostream>
     2
     3 int main()
     4 {
     5     int total = 0;
     6     int i = 1;
     7     while (i <= 100) {
     8         total += i;
     9         ++i;
    10     }
    11     std::cout << total << std::endl;
    12     return 0;
    13 }
   
   
   If we compile this program with "g++ -g q2.cpp -o q2.exe", and run "gdb q2.exe" with the following commands, what value of i shall we obtain?
   

   break 9 if total >= 666
   run
   print i
   
   
   

3. (10%) Predict the output of the following code.
   // Destructor
   #include <iostream>
   
   class CInt {
       int value;
   public:
       CInt(int v=0): value(v) {
           std::cout << "Constructor for " << value << std::endl;
       }
   
       ~CInt() {
           std::cout << "Destructor for " << value << std::endl;
       }
   };
   
   int main() {
       CInt a(4);
       CInt b(25);
       return 0;
   }