CODEWITHSUNDEEP
c#
user584018
user584018

Reputation: 11304

how to skip multiple iterations and improve code

In the below C# code, I am doing 2 iterations over data and trying to create a filter that looks like this,

(Name1 = 'd1' AND Name2 = 'd1') OR (Name1 = 'd3' AND Name2 = 'd3') OR (Name1 != 'd1' AND Name1 != 'd3')

For the below sets of data:

var data = new List<(string, string)>
{
    ("d1", "d2"), ("d3", "d4"),
};

Here is code:

foreach(var entity in data)
{
    filter += $"(Name1 = '{entity.Item1}' AND Name2 = '{entity.Item1}') OR ";
}

filter = filter + "(";

foreach (var entity in data)
{
    filter += $"Name1 != '{entity.Item1}' AND ";
}

//remove last "AND"
var final = filter.Substring(0, filter.LastIndexOf("AND")).TrimEnd() + ")";

How I can improve this code and get rid of 2 iterations? Thanks.

Upvotes: 1

Views: 103

Answers (2)

Connor Low
Connor Low

Reputation: 7186

Use Linq and string.Join to iterate once and avoid SubString:

var data = new List<(string, string)> { ("d1", "d2"), ("d3", "d4"), };

var exclude = new List<string>();
var filters = string.Join(" OR ", data.Select(entity => {
    exclude.Add($"Name1 != '{entity.Item1}'");
    return $"(Name1 = '{entity.Item1}' AND Name2 = '{entity.Item1}')";
}));
string final = $"{filters} OR ({string.Join(" AND ", exclude)})";

Upvotes: 2

ADyson
ADyson

Reputation: 61839

You can have two filter strings which you build up simultaneously and then combine at the end:

    string filter = "";
    string filter2 = "";
    
    var data = new List<(string, string)>
    {
        ("d1", "d2"), ("d3", "d4"),
    };
    
    foreach(var entity in data)
    {
        filter += $"(Name1 = '{entity.Item1}' AND Name2 = '{entity.Item1}') OR ";
        filter2 += $"Name1 != '{entity.Item1}' AND ";
    }

    filter2 = filter2.Substring(0, filter2.LastIndexOf("AND")).TrimEnd();
    string final = $"{filter}({filter2})";

Live demo: https://dotnetfiddle.net/TGr6Jz

Upvotes: 2

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