C#

/* required
using System;
using System.Collections.Generic;
using System.ComponentModel;
*/
public static class ConversionExtensions
{
    public enum ConversionType
    {
        SByte, Byte, Int16, Int32, Int64,
        UInt32, UInt64, Single, Double,
        Guid
    }

    static Dictionary<Type, TypeConverter> TypeToConverter = null;

    public static T? TryParse<T>(this string str) where T : struct
    {
        if (TypeToConverter == null)
        {
            TypeToConverter = new Dictionary<Type, TypeConverter>();

            foreach (string ct in Enum.GetNames(typeof(ConversionType)))
            {
                var t = Type.GetType("System." + ct);

                TypeToConverter.Add(t, TypeDescriptor.GetConverter(t));
            }
        }

        Type type = typeof(T);

        // using C# 7 syntax for in-line out variable
        if (TypeToConverter.TryGetValue(type, out TypeConverter tc))
        {
// tbd: use 'TypeConverter.CanConvertFrom here rather than try/catch
            try
            {
                return (T) tc.ConvertFromString(str);
            }
            catch
            {
                return null;
            }
        }
        else
        {
            throw new KeyNotFoundException($"this converter does not handle Type: {type.FullName}");
        }

        return null;
    }
}

cant send file bigger that 1 megabit ( Server_client )

        private byte[] GetFileInfo(string fname, string fext, long fsize)
        {
// i was not attention to this Code
// The problem was from here 1024 ,i changed it to 102400000 now correctly working thanks
            byte[] data = new byte[1024];//<--
            byte[] type = Encoding.UTF8.GetBytes("fff");

            byte[] ext = Encoding.UTF8.GetBytes(fext);
            byte[] extE = Encoding.UTF8.GetBytes(":");

            byte[] sizeS = Encoding.UTF8.GetBytes(fsize.ToString());
            byte[] sizeE = Encoding.UTF8.GetBytes("s");

            byte[] name = Encoding.UTF8.GetBytes(fname);
            byte[] nameE = Encoding.UTF8.GetBytes("?");

            Array.Copy(type, data, type.Length);
            Array.Copy(ext, 0, data, type.Length, ext.Length);
            Array.Copy(extE, 0, data, ext.Length + type.Length, extE.Length);
            Array.Copy(sizeS, 0, data, ext.Length + type.Length + extE.Length, sizeS.Length);
            Array.Copy(sizeE, 0, data, ext.Length + type.Length + extE.Length + sizeS.Length, sizeE.Length);
            Array.Copy(name, 0, data, ext.Length + type.Length + extE.Length + sizeS.Length + sizeE.Length, name.Length);
            Array.Copy(nameE, 0, data, ext.Length + type.Length + extE.Length + sizeS.Length + sizeE.Length + name.Length, nameE.Length);
            byte[] newdata = new byte[ext.Length + extE.Length + sizeS.Length + sizeE.Length + name.Length + nameE.Length + type.Length];
            Array.Copy(data, newdata, newdata.Length);
            return newdata;
        }
        private byte[] GetBinaryFile(string filename)
        {
            byte[] bytes;
            using (FileStream file = new FileStream(filename, FileMode.Open, FileAccess.Read))
            {
                bytes = new byte[file.Length];
                file.Read(bytes, 0, (int)file.Length);
            }
            return bytes;
        }
    }
}