[SOLVED] COMP2113 Module7-Self-Review Exercise

1. Assume that each of the following statement applies to the same program.
   1. Write a statement that opens file dat for input; use an ifstream object called inTransaction.
   2. Write a statement that opens file dat for input; use an ifstream object called inBalance.
   3. Write a statement that reads integer accountNumber, floating-point amount from the file dat; use ifstream object inTransaction.
   4. Write a statement that reads integer accountNumber, string name, floating-point currentBalance from the file dat; use ifstream object inBalance.
   5. Write a statement that writes integer accountNumber, string name, updated balance which is a floating-point currentBalance + amount to the file dat; use ifstream object inBalance.
2. Suppose that numStudents is an int variable and classCode is a string What are the values of numStudents and classCode after the following input statements execute:

cin >> numStudents;

getline(cin, classCode);

if the input is:

1. 80 ENGG1111
2. 80

ENGG1111

3. The following program is supposed to read two numbers from a file named dat and write the product of the numbers to a file named product.dat. However, it fails to accomplish the task.  Fix by rewriting the program so that it performs what it is supposed to do.

#include <iostream> #include <fstream> using namespace std;

int main()

{

int num1, num2;  ifstream infile;

outfile.open(“product.dat”);  infile >> num1 >> num2;

outfile << “Product = ” << num1 * num2 << endl;  return 0;

}

4. Consider the following statements:

struct movieType

{

string title;                string genre;                int year;            double rating;

};

movieType    movies[100];

movieType    oldMovie;

State if each of the following statements is valid or invalid.  If a statement is invalid, explain why.

• cout << oldMovie.name;
• year = 2015; (c) movies[11] = oldMovie;

(d)       oldMovie.title = “Titanic”; (e)             if (movies[99].genre == “drama”)

movies[99].rating = 3.5;

5. The following program calculates the summation of first n natural numbers. E.g., 𝑖𝑓 𝑛 = 6, 𝑠𝑢𝑚 =

1 + 2 + 3 + 4 + 5 + 6 = 21. Rewrite the sum() that uses recursion to calculate and return the sum of first n.

#include <iostream> using namespace std;

// iterative version int sum(int n)

{

int sum = 0;

for (int i = 1; i <= n; ++i)

sum += i;

return sum;

}

int main()

{

int n;

cout << “Enter a positive integer: “;  cin >> n;

cout << “Sum of first ” << n << ” natural numbers = ” << sum(n) << endl;

return 0;

}