I have earlier suggested that lexical_cast adds locale support so you can actually use it to parse something else than unformatted integers but the reply quoted the following text from the documentation: --- Start quote --- - It is also worth mentioning future non-directions: anything that involves adding extra arguments for a conversion operation is not being considered. A custom keyword cast, such as lexical_cast, is intended to look like a built-in cast operator: built-in cast operators take only a single operand. Where a higher degree of control is required over conversions, the standard stringstream offers a more appropriate path. Where non-stream-based conversions are required, lexical_cast is the wrong tool for the job, and so it won't be special-cased for such scenarios. --- End quote ---