Question

In Objective-C, is there any difference between n++ and ++n (eg. used in a for loop)?

Answer 1

++n; increments the value of n before the expression is evaluated.

n++; increments the value of n after the expression is evaluated.

So compare the results of this

int n = 41;
int o = ++n; //n = 42, o = 42

with the results of this:

int n = 41;
int o = n++; //n = 42, o = 41

In the case of loops:

for (int i = 0; i < j; i++) {/*...*/}

however it doesn’t make any difference, unless you had something like this:

for (int i = 0; i < j; x = i++) {/*...*/}

or this:

for (int i = 0; i < j; x = ++i) {/*...*/}

One could say:

It doesn’t matter whether to use n++ or ++n as long as no second (related) variable is modified (based on n) within the same expression.

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The same rules apply to --n; and n--;, obviously.