multiple 'if...else...' statement in one line in c++

Question

How to do if i want to get this code into one line?

if (count >= 0 && count <= 199) {
        return 1;
    } else if (count >= 200 && count <= 399) {
        return 2;
    } else if (count >= 400 && count <= 599) {
        return 3;
    } else if (count >= 600 && count <= 799) {
        return 4;
    } else {
        return 5;
    }

I'm just figuring is there any shortcut for this few line of codes.

I'd recommend a switch statement to eliminate the multiple if/else. — devlin carnate, Dec 08 '15 at 16:49
@KarolyHorvath - Google switch statement? For example: http://www.tutorialspoint.com/cplusplus/cpp_switch_statement.htm — devlin carnate, Dec 08 '15 at 18:23
@devlincarnate: If you didn't get the point of my comment, try to write this code with switches. I'm serious. — Karoly Horvath, Dec 08 '15 at 18:31
@KarolyHorvath - two comments. first, when I made my original comment, this question didn't have a tag and no indication of language. So my comment was a general one. second, I fail to see what the trouble would be in using a switch statement with that code. switch(count) followed by the comparisons and returns. In the languages I'm familiar with, [it is preferable to avoid multiple if/else and use a switch statement instead](http://stackoverflow.com/questions/449273/why-the-switch-statement-and-not-if-else). Apparently you have a differing opinion, which is fine. — devlin carnate, Dec 08 '15 at 18:40
@devlincarnate: You fail to see it because you didn't write code and test it. There's an opportunity to learn something here. — Karoly Horvath, Dec 08 '15 at 18:43
@devlincarnate C++ switch statements don't work the way you seem to think. — Rob K, Dec 08 '15 at 20:03
@devlincarnate "No indication of language"... Try reading the title sometime. — Ben Voigt, Dec 08 '15 at 20:04
As a side note, the structure he's given could leave out all of the `else`s since each clause `return`s — Rob K, Dec 08 '15 at 20:06
@BenVoigt - you're right. it was in the title and i missed it. oh well... with less than 4 hours of sleep last night, perhaps an oversight is warranted. — devlin carnate, Dec 08 '15 at 20:55

Scott Hunter · Accepted Answer · 2015-12-08T16:53:41.147

6

return ( count >= 0 && count <= 799 ) ? (1 + count / 200) : 5;

That is: if count is in range, you are returning successive values for each span of 200, and if it is out of range, you are returning 5.

edited Dec 08 '15 at 16:53

answered Dec 08 '15 at 16:51

Scott Hunter

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score 1 · Answer 2 · answered Dec 08 '15 at 19:58

If you can't compute the range directly from the count as shown in Scott Hunter's answer (e.g., if the ranges aren't uniformly sized or the values they map to don't form a simple pattern), you can encapsulate a little table lookup like this:

#include <algorithm>
#include <utility>
#include <vector>

int FindRange(int count) {
  static const std::pair<int, int> ranges[] = {
    {   0, 5 },
    { 200, 1 },
    { 400, 2 },
    { 600, 3 },
    { 800, 4 }
  };
  const auto it = std::find_if(std::begin(ranges), std::end(ranges),
                               [=](const std::pair<const int, int> &range) {
                                 return count < range.first;
                               });
  return (it == std::end(ranges)) ? ranges[0].second : it->second;
}

You can then change the table values and, as long as you keep them sorted, this function will continue to work.

It's a linear search through the table, so it should be on-par with the performance of a cascaded if-else.

score 0 · Answer 3 · answered Apr 30 '21 at 20:33

0

return 1 + std::min(count, 800) / 200;

should do. The if is hidden in std::min. If count is larger than 800, it is replaced by 800, and std::min(count, 800) / 200 is equal to 4.

answered Apr 30 '21 at 20:33

Eric Duminil

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multiple 'if...else...' statement in one line in c++

3 Answers3