How to generate unique integer from string?

Be wary of string.GetHashCode().

The .Net documentation states https://msdn.microsoft.com/en-us/library/system.string.gethashcode(v=vs.110).aspx

The hash code itself is not guaranteed to be stable. Hash codes for identical strings states can differ across versions of the.NET Framework and across platforms (such as 32-bit and 64-bit) for a single version of the .NET Framework. In some cases, they can even differ by application domain

Just take string.GetHashCode() which returns an int from a string with very low collision probability.