We have:
    // sorted values
    size_t lines  = [20, 1755, 1756, 1757, 1798, 1824, 1825, 1839, 1840];
    size_t search = 21;

Goal:
    // Fast find index of the '21' in ordered array 'lines'
    auto found = lines.binarySearch( 20 );     // 0 - index
    auto low   = lines.binarySearchLow( 21 );  // 0 - near lowest index

Where is the implementation of "binary search", please?

Phobos provides this by SortedRange:
https://dlang.org/phobos/std_range.html#.SortedRange

Example of usage:
https://run.dlang.io/is/WW2bn0

On Monday, 7 December 2020 at 06:24:27 UTC, drug wrote:
> Phobos provides this by SortedRange:
> https://dlang.org/phobos/std_range.html#.SortedRange
>
> Example of usage:
> https://run.dlang.io/is/WW2bn0

Thanks!
:-)