using System;
using System.Linq;
using System.Globalization;
 
public class Test
{
	public static void Main()
	{
        string sTemp = "10.12;12.13;15.345";
 
            var doubles = sTemp.Split(';')
                .Select(s => double.Parse(s, CultureInfo.InvariantCulture));
 
            var locale = System.Globalization.CultureInfo.CreateSpecificCulture("fr-FR");
            // or var locale = System.Globalization.CultureInfo.CurrentCulture;
 
            var localeDoubleStrings = doubles.Select(d => d.ToString(locale));
            foreach (string frDoubleStr in localeDoubleStrings)
                Console.WriteLine(frDoubleStr);
	}
}

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