Exercise 5.16

The while loop is particularly good at executing while some condition holds; for example, when we need to read values until end-of-file. The for loop is generally thought of as a step loop: An index steps through a range of values in a collection. Write an idiomatic use of each loop and then rewrite each using the other loop construct. If you could use only one loop, which would you choose? Why?

Solution

char c;
int i;

// idiomatic examples
while ((c = getchar()) != EOF)
    // ...
for (i = 0; i < 100; ++i)
    cout << i << endl;

// using the other loop type
for (/* null */; (c = getchar()) != EOF; )
    // ...
i = 0;
while (i < 100)
    cout << i++ << endl;

I would prefer to use only for loops if I had to, since the functionality of the while loop can be replicated by just including no init statement and no step statement.