atof() to double problem

This is really not an issue.
It's just the way floating point numbers are represented.

When you say returns, you're actually doing a printf here.
So if printf("%f", dbTest); returns 1.00299999, check what printf("%.3f", dbTest); returns.

As Saurabh said:

This this because binary numbers cannot represent all possible real numbers. So when you specify a real number which cannot be represented then its nearest real number is used.


Just another thing: there cannot exist two overloads of a functions that differ only by the return value. This means that on your code snippet, you are always calling the function double atof(const char *buffer), and the compiler implicitly casts the returned value to float. This means that there is nothing strange under the hood with double arithmetic and atof function, as Adam Roderick J erroneusly asserted.

I have noticed this issue with swprinf in VS 2008, and then i dig the reason behind it.
And i found that last bit is having lose with the data in last bit, which is lost in arithmetic of double operations. I believe atof is having some sort of arithmetic that is creating the loss.
So a solution such problem is what i was looking and i found it in codeproject in the below mentioned article:- Five Tips for Floating Point Programming[^]