HW-1

HW-1 / Chapter 1 “The Phases of Software Development” 1. Why is writing easily modifiable code important?  A. Easily modifiable code generally has a quicker run time.  B . Most real-world programs require change at some time.  C. Most text editors make it easy to modify code.  D. Several people may be writing the same function at the same time. 2. Which phase of the software life-cycle is usually the most expensive?  A. Analysis and specification of the task  B. Design  C. Implementation  D . Maintenance and evolution 3. What will happen if a function is executed and the precondition for the function is not met?  A. An error message will be printed.  B. The program will loop indefinitely.  C. The system will crash.  D . Any of the above results could happen. * 4. Answer true or false for this statement: When programming in teams, the specification of a function should be written by the person writing the code for the function.  TRUE.  FALSE . 5. If the precondition fails, it is a good idea to write a useful error message and then halt the program. Why is the program halted?  A. Most operating systems forbid continuation.  B . The function is no longer guaranteed to make the postcondition true.  C. The function's memory requires have become exponential (or worse).  D. The function's running time has become exponential (or worse). 6. Which of these functions can be used to stop the program execution when a precondition is not met.  A . assert();  B. exit();  C. return();  D. void(); 7. Which of these function calls will cause an exception to be thrown when x is 23. (x is an int variable).  A. if (0 == x) throw std::invalid_argument(“Wrong x”);  B . if (0 < x) throw std::invalid_argument(“Wrong x”);  C. if (0 > x) throw std::invalid_argument(“Wrong x”);  D. None of the above will cause an exception when x is 23.

8. Determine which of the following formulas is O(n) :  A. 16 n 3  B . n 2 + n + 2  C. | n 2 /2|  D . 10 n + 25 9. What does a run-time analysis usually count?  A . The number of arithmetic and other operations required for the program to run  B. The number of megabytes required for the program to run  C. The number of seconds required for the program to run  D. The number of seconds plus the number of megabytes  E. The number of seconds times the number of megabytes 10. Here is some code for an  integer  variable n: while (n > 0) { n = n/10; // Use integer division } What is the worst-case time analysis for the above loop?  A. O(1)  B . O(log n) // Any algorithm which   cuts the problem in half   each time is O(log n).  C. O(n)  D. O(n²) 11. What term is used to describe an O(n) algorithm.  A. Constant  B . Linear  C. Logarithmic  D. Quadratic 12. Why is it important to test boundary values when testing programs?  A. Calculating by hand, it's easy to find the right answers for boundary values.  B. Debuggers are easier to use when testing boundary values.  C . In practice, a large proportion of errors arise from boundary values.  D. The correct execution of a function on all boundary values proves a function is correct. 13. Which software tool will best help you determine whether your test cases are fully exercising your code?  A. Compiler  B. Debugger  C. Make  D. Pine  E . Profiler