Convert to a datatype given in string format
I have been searching for a solution for quite a while now and couldn't find anything close.
What I want to achieve:
I have two strings, 'a' and 'b'. String 'a' contains a datatype, for example "Boolean". String b contains a value like "1" or "False", could be anything. I want to be able to store the value of string 'b' in a variable which has the dataty开发者_开发知识库pe of string 'a'.If I would itterate trough a list of results with the same values as given in the example the results would be as following:
Foreach(var value in MyList)
{
if(!var ConvertTo a) //Result would be negative because for "1" for it is not a boolean value, however if 'a' is "Int32" the result would be true.
continue;
else
{//The value "False" is convertable to boolean, so the result would true
Create a variable with datatype boolean with the value 'false'.
}
}
More or less i'm in search of some strangly hacked version of TryParse().
I used boolean in my example, but this can be any datatype. At least I should be able to handle atleast the following datatypes:
- Int, Int32, Int64
- string
- Boolean
- float, decimal
- DateTime
My question:
Is it possible in any way to (try to) convert a value to any datatype given in a string?I hope my question and example is clear, if not please leave a comment.
You have to map the strings to a type. Since not all of them are System.<yourType>
directly, I would consider creating a mapping:
Dictionary<string, Type> types = new Dictionary<string, Type>();
types.Add("int", typeof(System.Int32);
//etc.
Then, use Convert.ChangeType to get your object:
object myObj = Convert.ChangeType(b, types[a]);
Maybe you could extend this by trying to get the type if the key does not exist in your type mapping:
object myObj = Convert.ChangeType(b, Type.GetType("System." + a));
in general if you know the type name you can do this:
Type type = Type.GetType("System.Data.OleDb.OleDbParameter");
for example, so you must anyway know the full name of the type.
said so, if you have an object which was set from the caller to a certain value, you can do a GetType()
on the object and get its actual type.
if "True" comes as string, you have no way to distinguish if should be a bool or a string.
If you want to use the TimeSpan
datatype, you cannot use ChangeType()
.
An alternative is to use TypeConverter.ConvertFrom()
:
var asString = "0";
var textType = "System.Int32";
var dataType = Type.GetType(textType);
var converter = TypeDescriptor.GetConverter(dataType);
var newValue = converter.CanConvertFrom(asString) ?
converter.ConvertFrom(asString) :
asString;
As with the other answers, it assumes you know what type you're casting to.
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