Question

I am trying to do something like the following:

stringstream convert1(Model_str.substr(2, 12));
cout << (Model_str.substr(2, 12)) << endl; //output = 0.999999
convert1>>vertex1[VertexCounter];
cout << vertex1[VertexCounter] << endl; //output = 0

Is there a reason why it is not being precise to 6 decimal places when placing it into my array?

Answer 1

When you extract an int from a stream with >>, it reads for as long as there are characters that could be considered part of an int. Integers do not allow for fractional parts, so there are no decimal points in int values. It read the 0 from the stream, stored it in your vertex1 array element (assuming vertex1 is an array of int), and left the remaining characters on the input buffer for a later read operation to consume.

If you want to read a floating-point string from a stream, you at the very least need to read into a type that supports floating-point values, such as float or double. Whether you get the precise value you expected is another matter. The target type you choose might not be able to represent the exact value you want it to.