There is typo error in NumberFormatInfo.NegativeSign Property Example Doc.
In the example, an instance of CultureInfo is defined with the variable name ci. While converting a number into a string, culture variable is used instead of variable name ci.
Due to this typo error, C# compile is throwing below error,
Compilation error (line 13, col 44): The name 'culture' does not exist in the current context
Affected Languages: C#, VB.NET
.net Fiddle