Authors:
Walter Savitch ,julia Lobur
Chapter:
Arrays
Exercise:
Self-test Exercises
Question:8 | ISBN:9780321531346 | Edition: 7
Question
Suppose we expect the elements of the array a to be ordered so that
a[0] ≤ a[1] ≤ a[2]≤ ...
However, to be safe we want our program to test the array and issue a
warning in case it turns out that some elements are out of order. The
following code is supposed to output such a warning, but it contains a
bug. What is it?
double a[10];
<Some code to fill the array a goes here.>
for (int index = 0; index < 10; index++)
if (a[index] > a[index + 1])
cout << "Array elements " << index << " and "
<< (index + 1) << " are out of order.";
Answer
The bug in the provided code is the condition inside the for loop where it checks a[index] > a[index + 1].
- This condition will cause an out-of-bounds access when
indexreaches the last element of the array (index = 9), as it tries to accessa[9 + 1], which is beyond the array bounds. - To fix this bug, we need to modify the condition to ensure that the loop only iterates up to the second-to-last element of the array.
- Here's the corrected code:
double a[10];
// Some code to fill the array a goes here.
for (int index = 0; index < 9; index++)
{
if (a[index] > a[index + 1])
{
cout << "Array elements " << index << " and " << (index + 1) << " are out of order.";
}
}
- In the corrected code, the condition in the
forloop is changed toindex < 9, which ensures that the loop only iterates up to the second-to-last element of the array (a[8]). - This prevents the out-of-bounds access when accessing
a[index + 1].