Section 10.4 for
loops
The loops we have written so far have a number of elements in common. All of them start by initializing a variable; they have a test, or condition, that depends on that variable; and inside the loop they do something to that variable, like increment it.
This type of loop is so common that there is an alternate loop statement, called
for
, that expresses it more concisely. The general syntax looks like this:
for (INITIALIZER; CONDITION; INCREMENTOR) {
BODY
}
This statement is exactly equivalent to
INITIALIZER;
while (CONDITION) {
BODY
INCREMENTOR
}
except that it is more concise and, since it puts all the loop-related statements in one place, it is easier to read. For example:
int i;
for (i = 0; i < 4; i++) {
cout << count[i] << endl;
}
is equivalent to
int i = 0;
while (i < 4) {
cout << count[i] << endl;
i++;
}
for
loop.while
loop.The
INCREMENTOR
does not have to do ++
to a variable. It can be any statement you like, but it should do something to modify the looping variable. If you want to count down, you could use i--
as your INCREMENTOR
.
for
loop with a negative change in the “INCREMENTOR”.Checkpoint 10.4.2.
Checkpoint 10.4.3.
Construct the
half_life()
function that prints the first num half lives of the initial amount.
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