Chapter 6 Looping
Chapter 6
EXERCISE ANSWERS
Exam Preparation Exercises
1. Loops are segments of code that are repeated from 0 to many times until some stopping condition is
met. Branches are segments of code that may be executed 0 or 1 times, depending on evaluation of
the logical expression in the If statement.
2. The loop prints the integers 2 through 11, one number per line.
5. In the output below, the first two digits on each line are values of j, and the third digit is the value of i.
2 1 4
2 1 3
2 1 2
2 1 1
6. a. 4 6 8 10 12 14 16 18 20 and so on
b. The two flaws are the initial value of n and the While condition. n is initially set to 2, but the 2 is
not printed before n is incremented to 4. This flaw can be fixed by incrementing n after the
output statement instead of before it. The loop never stops because n never equals 15; n always
contains an even number. This may be corrected by changing the While condition to n < 15. The
corrected code is:
n = 2;
while (n < 15)
{
cout << n << ’ ’;
n = n + 2;
}
7. a. The output is BCDE, followed by an echo of the newline character. The ’A’ that is input by the
priming read is discarded because the statements in the loop body are in reverse order.
b. Corrected code:
cin.get(inChar);
while (inChar != ’\n’)
{
cout << inChar;
cin.get(inChar);
}
8. One (and only one) priming read is needed. It precedes the outer While loop:
cin.get(letter);
while (cin)
.
.
This input statement primes not only the outer loop but also the inner loop.
10. a. After exit from the loop, sum contains 18 and number contains 0.
b. No, the given data set does not fully test the program. Another set needs to be tested in which the
value of i reaches its limit, another in which the first data item is the sentinel value 0, and yet
another in which all data values before the sentinel are less than zero.
12. 1 3 6 10 15
7
1
