Is this the correct approach to do input validation with floating point values?

Question

After spending a good amount of time researching input validation, I combined a few ideas and came up with this:

Function to check a string for a valid dou

Answer 1

Based on the feedback of those who answered and some of the examples in other questions, I answered my own question. As per FailedDev's suggestion, this question should be marked answered. So here is the accepted answer. :)