Conversion from string "<fetch version='1.0' ><entity na" to type 'Double' is not valid."

Question

I am reading a string attribute from ms crm in temp string variable then i am converting it to type integer memcod so that i need to pass it as integer type to xml but it sounds strange i am not using a string or double its throws the following exception Conversion from string "<fetch version='1.0' ><entity na" to type 'Double' is not valid. Please help

Answer 1

The problem is the way you tried to concatenate a bunch of strings together with an integer, memcod, by using the + operator.

This code produces the same exception at runtime:

Conversion from string "<foo>" to type 'Double' is not valid.

Dim n as Integer = 0
Dim test As String = "<foo>" +
        n +
        "</foo>"

Clearly, VB sees the integer there and thinks that you're trying to do arithmetic. I guess it figures you want a double because it can't hazard a guess what else you might want. This bizarre code, for example, sets test to "11". That's a string equal to "11":

    Dim n As Integer = 0
    Dim test As String = "5" +
        n +
        "6"

You can work around this issue in two ways.

One, use VB's backwards compatible dedicated string concatenation operator instead of +:

    Dim test As String = "<foo>" &
        n &
        "</foo>"

Two, explicitly stringify n:

    Dim test As String = "<foo>" +
        n.ToString() +
        "</foo>"