Copying numbers from a "Number" field to a "Single Line" field?

Copying numbers from a "Number" field to a "Single Line" field?

Hello,

I have values listed in a "Number" field and would like to copy them in a new "Single Line" field.  I have tried first to simply change the type of the original field from Number to Single Line, but I am receiving the following error message when attempting to enter any type of entries (number and/or string):

"View Error Details java.lang.Long cannot be cast to java.lang.String"

Therefore I have created a new field (Single Line) and I am now looking for the specific function to copy-paste the current values.  But I don't know how to transfer numbers to strings.  The following script (for a custom action) cannot be saved as is...  :

void manipulation.No_Sales (Sales_USD Item7)
{
    for each n in Item7
    {
        n.No_Number = n.No_String;
    }
}

Thanks in advance!