cannot convert from 'void' to 'System.Collections.Generic.List<string> C#

Question

I'm trying to add a new List for each loop in the code below to a dictionary, but I'm currently struggling with the following error:

cannot convert from 'void' to 'System.Collections.Generic.List

public class WeaponGen{
Dictionary<string, List<string>> weapons = new Dictionary <string, List<string>>(); 

public void WeaponGeneration(int GenerationCount)
{
    Weapon weapon = new Weapon(); //this class contains basic calculation methods
    weapons.Clear();

    for (int i = 0; i < GenerationCount; i++)
    {
        string listname = "weapon" + i;
        string id = Random.Range(1, 41).ToString();

        List<string>[] _lists = new List<string>[GenerationCount];
        _lists[i] = new List<string>();

        weapons.Add(listname, _lists[i].Add(id)); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetName(id))); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetRarity(id))); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetType(id))); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetDmg(id).ToString())); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetSpeed(id).ToString())); //this line throws an error
        weapons.Add(listname, _lists[i].Add(weapon.GetCost(id).ToString())); //this line throws an error
    }
}}

Since my coding skills are definitly lacking in some aspects, I figured someone with a better grasp on the language could help me out. Every help is greatly appreciated!

Answer 1

Welcome to SO!

List add method does not return any value: https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.list-1.add?view=netframework-4.7.2.

So, if I understood your idea correctly, you need to fill the list with needed values and add it itself to the dictionary, like this:

for (int i = 0; i < GenerationCount; i++)
{
    string listname = "weapon" + i;
    string id = Random.Range(1, 41).ToString();

    List<string>[] _lists = new List<string>[GenerationCount];
    _lists[i] = new List<string>();

    _lists[i].Add(id); 
    _lists[i].Add(weapon.GetName(id)); 
    _lists[i].Add(weapon.GetRarity(id)); 
    _lists[i].Add(weapon.GetType(id)); 
    _lists[i].Add(weapon.GetDmg(id).ToString());
    _lists[i].Add(weapon.GetSpeed(id).ToString()); 
    _lists[i].Add(weapon.GetCost(id).ToString());
    weapons.Add(listname, _lists[i]);
}

P.S. What is it Random.Range? Is it some extention method? In any case, it seems to be dangerous to generate id's based on random value in such small interval. Why not simple use i.ToString()?