Loop through list of strings to find different values

user_9931604 0
Viewed 71

I have a list that is populated with different values:

e.g

{GBP, GBP, GBP, USD}

so far I have this:

List<string> currencyTypes = new List<string>();

for (int i = 0; i < currencyTypes.Count; i++)
{
    if currencyTypes[i] != [i]
        console.writeline("currencies are different");
}

So if the list has all the same entries, the if statement shouldnt fire

e,g {GBP, GBP, GBP, GBP}

however if any of the values are different from the rest then the if statement should notice the difference and fire.

this doesnt work however.

any ideas?

list loops string c#
3 Answers

First of all, your list is empty. Maybe it's for the sake of the example. If not, initialize it with data. However, modify line 3 and 5 to this to fix the problem.

for (int i = 1; i < currencyTypes.Count; i++)
{
    if (currencyTypes[i] != currencyTypes[i-1])
   .... 
 }
user_50935940

You could use LINQ to test whether all entries are the same

if (currencyTypes.Distinct().Count() > 1) {
    Console.WriteLine("currencies are different");
}

Slightly more efficient for long lists:

if (currencyTypes.Count > 1 && currencyTypes.Distinct().Skip(1).Any()) {
    Console.WriteLine("currencies are different");
}

This is more efficient because Any iterates at most one element unlike Count which iterates the whole list.

user_8809900

you should first group your data and find your result depending the group.

eg

    List<string> currencyTypes = new List<string>() {"USD", "GBP", "GBP", "GBP" };

    // group list items
    var typeGroup = currencyTypes.GroupBy(t => t);
    
    if (typeGroup.Count() > 1)
        Console.WriteLine("currencies are different");
    // .    
    // .
    
    // also you can check what item is unique   
    foreach (var t in typeGroup.Where(g => g.Count() == 1 ))
    {
        Console.WriteLine($"{t.Single()} is different");
    }
user_7863760
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