Code shared from run.dlang.io.

main.d

import std.stdio;
void main()
{
    string list = "3, 5, 1, , not a number, 100";
    
    import std.algorithm;
    import std.string;
    import std.conv;
    import std.range : array;

    int[] numbers = list.split(",").filter!((entry) {
        if (!isNumeric(entry.strip))
            return false;
        else // ... even more cases?
            return true;
    	})
        .map!((e) => e.strip.to!int).array;

    assert(numbers == [3, 5, 1, 100]);
}