I have a function that has int a and int b all I have to do is find the max value

Question

I keep getting the following error (warning: control may reach end of non void function [-Wreturn-type])

This is what I have right now.

int min(int a, int b) {
    if (b > a) {
        return a;
    }
    if (a > b) {
        return b;
    }
}

What do you think will happen when `a == b` ? Incidentally, you return the **min** value not the **max** in the question title. — Weather Vane, Apr 06 '19 at 16:22
Possible duplicate of [Error: control may reach end of non-void function in C](https://stackoverflow.com/questions/22410538/error-control-may-reach-end-of-non-void-function-in-c) — Denis Zavedeev, Apr 06 '19 at 16:34

Bathsheba · Answer 1 · 2019-04-06T16:57:13.723

2

If b == a then there is no explicit return value. Your compiler is warning you of that.

This is why you should always use a final } else { block.

Although adding

if (a == b){
    return a; // either would do
}

would be an immediate fix, such a change could cause you problems in the future, if you ever write a version of min that takes double types, and one of the inputs is NaN. No compiler I know of currently warns you of that.

Really though, you should ditch this function entirely and use the one from a respected library. For a whole host of technical reasons, the canonical way of writing min is to use

return (b < a) ? b : a;

edited Apr 06 '19 at 16:57

answered Apr 06 '19 at 16:22

Bathsheba

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*use the one from the C standard library.* I'm afraid there is no `min` function in the Standard C library. – chqrlie Apr 06 '19 at 16:48
@chqrlie Ha. That will teach me. I’ve edited. Could have sworn I had min, minf and so on at university. Posix perhaps? – Bathsheba Apr 06 '19 at 16:57
I had the same feeling and it took me a while to check in the Standard... There is `int abs(int)` and floating point versions `double fmin(double x, double y);`, `float fminf(float x, float y);` and `long double fminl(long double x, long double y);`, but no integer `min` nor a generic version. – chqrlie Apr 06 '19 at 19:28

bruno · Answer 2 · 2019-04-06T16:28:42.460

1

in

int min(int a, int b) {
    if (b > a){
        return a;
    }
    if (a > b){
        return b;
    }
}

you missed the case where a==b

can be just

int min(int a, int b) {
  return (a < b) ? a : b;
}

edited Apr 06 '19 at 16:28

answered Apr 06 '19 at 16:26

bruno

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ok changed for `<` rather than `<=` if you prefer, but that changes absolutely nothing on the result ^^ – bruno Apr 06 '19 at 16:29
`return (b < a) ? b : a;` pretty please with sugar on top. – Bathsheba Apr 06 '19 at 16:30
@Bathsheba that time I do not understand at all the interrest, please can you explain ? – bruno Apr 06 '19 at 16:31
bruno: ask that as a question, I'll be sure to upvote it. – Bathsheba Apr 06 '19 at 16:32
@Bathsheba sorry but I prefer to follow the order of the parameters ;-) – bruno Apr 06 '19 at 16:33
Well that makes you a very naughty boy. Your way breaks the signed zero convention for 1's complement `int`. – Bathsheba Apr 06 '19 at 16:33
I have already changed to please you, but I will not change for an upvote, I am not for sale ^^ – bruno Apr 06 '19 at 16:34
But I'm not pleased since you break the convention! – Bathsheba Apr 06 '19 at 16:35
@Bathsheba I am a rebel, and at my age I am afraid it is too late to change :-) – bruno Apr 06 '19 at 16:36
Respect.͏͏͏͏͏͏͏͏͏͏͏ – Bathsheba Apr 06 '19 at 16:36
(But note that the C tag is the final bastion for perfectionists - you might attract the odd downvote). – Bathsheba Apr 06 '19 at 16:37
@Bathsheba did you noticed the more the initial problem is simple the more we discuss and have different points of view ? ^^ – bruno Apr 06 '19 at 16:37
But my point of view is the correct one. Sorry but I can't resist that. My only problem is that I'm conceited. I'm too old to change that. – Bathsheba Apr 06 '19 at 16:38
Different language I know but see https://en.cppreference.com/w/cpp/algorithm/min – Bathsheba Apr 06 '19 at 16:39
@Bathsheba: *ask that as a question, I'll be sure to upvote it*... be my guest :) https://stackoverflow.com/questions/55552778/what-is-the-best-implementation-of-min – chqrlie Apr 06 '19 at 19:39

I have a function that has int a and int b all I have to do is find the max value

2 Answers2