Solutions to Midterm

Solutions to Midterm

(35 points) Consider the following C++ program: ...
1. (5 points) What does it output?
```
30
```
2. (5 points) Write a description of this program, as you would put in its header comment. Do NOT include the author or dates that normally appear in the header comment.
```
The program computes the sum of the even integers between
0 and 10, inclusive.  The result is ouput to the terminal
```
3. (5 points) When the program is run and reaches line 18, what is the value of the variable i at that point?
```
11
```
4. (5 points) Suppose line 11 were changed to
```
while (i < 10) {
```
  What effect would this have on the program?
```
The program would output 20 instead of 30 [since 10 would
not be added.]
```
5. (5 points) Suppose line 11 were changed to
```
while (i >= 10) {
```
  What effect would this have on the program?
```
The program would output 0 [since the loop would fail
immediately].
```
6. (5 points) Suppose line 16 were changed to
```
i++;
```
  (and line 11 is in its original form "while (i <= 10)"). What effect would this have on the program?
```
No change [since i++ is equivalent to i = i + 1].
```
7. (5 points) Suppose line 16 were removed entirely from the program (and line 11 is in its original form). What effect would this have on the program?
```
The program would go into an infinite loop [since i would be
stuck at 0].
```

(65 points) Write a C++ program per the specification given below. ...

#include <fstream.h>
#include <iomanip.h>
#include <iostream.h>

int main() {
    float balance;                      // Initial and ending balance
    float check_amount;                 // Amount of each check
    int num_checks = 0;                 // Number of checks read
    ifstream file;                      // Input file

    //
    // Set up floating point output format.  (NOT REQUIRED in student answer.)
    //
    cout.setf(ios::fixed, ios::floatfield);
    cout.setf(ios::showpoint);

    //
    // Prompt for and read the initial balance.
    //
    cout << "Input the initial balance: ";
    cin >> balance;

    //
    // Open checks file and read the first check amount.
    //
    file.open("checks");
    file >> check_amount;

    //
    // Process the remaining checks in the file, decrementing the balance and
    // incrementing the check counter as each is read.
    //
    while (file) {
        balance = balance - check_amount;
        num_checks = num_checks + 1;
        file >> check_amount;
    }

    //
    // Output the results.
    //
    cout << num_checks << " checks read.  "
         << "Final balance is "
         << setprecision(2) << balance
         << endl;
}