A simple string to valuetype converter using TypeDescriptor.

StringToValueTypeConverter.cs

using System;
using System.ComponentModel;

namespace TestForEverything
{
    /// <summary>
    /// Extension methos of string providing conversions to primitve types
    /// </summary>
    public static class ConverterExtensions
    {
        /// <summary>
        /// Method can be used to convert primitive types. It supports only converting IConvertible structs.
        /// </summary>
        /// <typeparam name="T">type for cast</typeparam>
        /// <param name="value">string representation of type value</param>
        /// <returns>casted value of given type</returns>
        public static T To<T>(this string value) // where T: struct
        {
            var newType = typeof(T);

            object result;

            if (TryConvertTo<T>(value, out result))
            {
                return (T)result;
            }

            throw new InvalidCastException(string.Format("Unable to cast the {0} to type {1}", value, newType));
        }

        /// <summary>
        /// Try converting by casting to special types struct like Enum, Guid and DateTime.
        /// </summary>
        /// <typeparam name="T">type for cast</typeparam>
        /// <param name="value">string representation of type value</param>
        /// <param name="result">casted value of given type</param>
        /// <returns>true, if cast is successful otherwise false.</returns>
        private static bool TryConvertTo<T>(this string value, out object result)
        {
            result = default(T);

            if (string.IsNullOrWhiteSpace(value))
            {
                return true;
            }

            try
            {
                var converter = TypeDescriptor.GetConverter(typeof(T));
                result = (T)converter.ConvertFromString(value);
                return true;
            }
            catch(Exception exception)
            {
               // Log the exception if required.
                // throw new InvalidCastException(string.Format("Unable to cast the {0} to type {1}", value, newType, exception));
                return false;
            }
        }
    }
}

Here are the tests written for this class.