Use range-based for & std::find to modernize codes in segmentation

[ueqri]

• use range-based for with const auto reference to gain more performance
• use std::find to improve code readability, solved issue in Use better for-loops #4599 (comment)

The changes are only in segmentation directory, as a small piece of modernization work. I'd be glad to continue working on this PR if needed. 😀

[kunaltyagi]

use range-based for with const auto reference to gain more performance

Any benchmarks for the perf increase?

[kunaltyagi]

Perhaps, we can rewrite the condition to exit early

for(loop) {
    const auto it = find();
    if (it == cend) { continue; }
    // rest of logic
    break;
}

[ueqri]

Using if (it == cend) { continue; } is more explicit, but could we just stay on the current to make it concise:blush:?

[ueqri]

Thanks for your kind reviews! 😀

Any benchmarks for the perf increase?

Sorry, I've not done the perf, I just suppose that using references instead of copies will produce more efficiency. The changes are a bit scattered(not focused on a certain function), so I'm a tad tentative about the benchmarks of this PR.

BTW: I'm quite interested in the benchmark jobs of our community. I find that the benchmark of pcl is in progress, #3860, #4718. So I was wondering if there are some plans or small pieces I can work for it. Since I have some experiences on clustering and high-performance computing, I think I am competent for the jobs.

[mvieth]

Just some minor things, else it looks good.

[mvieth]

@kunaltyagi Would you like to take another look at this or can it be merged?