More than one string required to match on, a better way?

Question

I am just looking if there is a better way to do the following.

Say I have the following strings:

string fooWeb = "web";
string fooDesktop = "desktop";
string fooMac = "mac";
string fooIphone = "iphone";
string fooAndroid = "android";


list<string> Names = new List<string>();
Names.Add("web");
Names.Add("mac");
Names.Add("iphone");
Names.Add("android");

I am looping through this list and i want to exclude the item which contains for example "web" & "mac" & and "android" there could be others too.

Is there a better way to achieve this than what I am trying below:

foreach (var item in this._repo.FooRepo())
if (!(item.SystemName == "Web" || item.SystemName == "android" || item.SystemName == "mac"))
{
  //add to new list
}
}

I am asking, as I have around 8 strings to check against.

better in what sense? better so that you don't need to list all the cases or that you want to have shorter code? For the latter you could use LINQ: `var list = this._repo.FooRepo().Except(new List { "Web", "android", "mac"});` but this creates additional list object which is not really needed. — Paweł Łukasik, Dec 19 '16 at 17:29
I guess the latter as it seems cumbersum to write all these out in the if statement, all the answers below are valid suggestions. I prefer this linq with .Except. I was looking for something like this. — Harry, Dec 19 '16 at 19:06

score 1 · Accepted Answer · answered Dec 19 '16 at 17:25

1

You could through them into an array and use the .Contains() method.

var validItems = new [] { "Web", "android", "mac" };

foreach (var item in this._repo.FooRepo())
{
    if (!validItems.Contains(item))
    {
        //add to new list
    }
}

answered Dec 19 '16 at 17:25

Matt Rowland

4,575
4
25
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I know I can do that, but also wouldn't I need to do that for each string? – Harry Dec 19 '16 at 17:27
1

You would just add the string to the array. If you have a set of valid data, you are going to need that persisted somewhere. That could be hardcoded into the array, in a database, in a config file, or some other way. – Matt Rowland Dec 19 '16 at 17:28
thanks, i will take your points on board :) – Harry Dec 19 '16 at 19:06
I will accept this, as this seems appropriate for my scenerio. – Harry Dec 20 '16 at 10:42

score 0 · Answer 2 · answered Dec 19 '16 at 17:33

0

First part simplified:

list<string> Names = new List<string> () {
    "web",
    "mac",
    "iphone",
    "android"
};

or:

var Names = new [] {
    "web",
    "mac",
    "iphone",
    "android"
};

or:

string[] Names = new string[] {
    "web",
    "mac",
    "iphone",
    "android"
};

Second part simplified:

myList.Add(this._repo.FooRepo().Where(i => !Names.Contains(i.SystemName)));

answered Dec 19 '16 at 17:33

maraaaaaaaa

7,749
2
22
37

thank you for your input :) – Harry Dec 19 '16 at 19:07

Alfie Goodacre · Answer 3 · 2016-12-19T19:20:44.610

-1

You could create your own method to evaluate any number of strings, which can be used whenever - in a separate, static class:

public static class StringFunctions
{
    public static bool IfContains(this string inString, params string[] comparisonStrings)
    {
        return comparisonStrings.Contains(inString);
    }
}

This can be called like so

if(!item.SystemName.IfContains("web", "desktop", "mac", "iphone", "android"))
{
    //add to new list
}

You can also pass an array into the method

string[] words = { "web", "desktop", "mac", "iphone", "android" };
if(!item.SystemName.IfContains(words))
{
    //add to new list
}

edited Dec 19 '16 at 19:20

answered Dec 19 '16 at 17:27

Alfie Goodacre

2,753
1
13
26

thank you for your input, this is how i would have done it. but i guess I was searching for a shorter way of doing it. – Harry Dec 19 '16 at 19:07
1

Your first method could be simplified to simply 1 line: `return comparisonStrings.Contains(inString);` – maraaaaaaaa Dec 19 '16 at 19:12
@maksymiuk of course, I was not thinking properly at all by the looks of it xD – Alfie Goodacre Dec 19 '16 at 19:20

More than one string required to match on, a better way?

3 Answers3