error when using std::copy

Question

Hey guys I'm having trouble with some code I'm writing for a .obj model parser. Here's the code that's causing the problem:

std::istringstream iss(line.substr(1));

std::copy(   
std::istream_iterator<float>(iss),     
std::istream_iterator<float>(),    
std::back_inserter<std::vector<float>>(model.chunks.back().vectices)  
);

It's basically taking a string passed as a argument like this:

v -5.000000 -1.000000 1.000000

Then gets the substring from it so it's left with only this:

-5.000000 -1.000000 1.000000

Finally I use std::copy and get each set of numbers from within the string:

vertices[0] = -5.000000
vertices[1] = -1.000000
vertices[2] = 1.000000

Anyways the main problem here is that I'm getting an error from this line of code:

std::back_inserter<std::vector<float>>(model.chunks.back().vectices));

It says "expected token ';' got float" my code still compiles and run's flawlessly though.

Although if I replace the floats in that code with std::string's I don't get the error anymore.

std::copy(  
std::istream_iterator<std::string>(iss),   
std::istream_iterator<std::string>(),   
std::back_inserter<std::vector<std::string>>(model.chunks.back().vectices)  
);

I'm using Qt Creator so could this possibly be just a IDE error? Any help would be greatly appreciated!

Why don't you just write std::back_inserter(model.chunks.back().vectices) and let the compiler deduce the type argument? — Sarfaraz Nawaz
– Sarfaraz Nawaz, Commented Aug 2, 2012 at 4:59
Hmm.. didn't think of that. It also requires less code. Thanks for the tip! — luveti
– luveti, Commented Aug 2, 2012 at 5:05

Greg Hewgill · Accepted Answer · 2012-08-02 04:39:30Z

4

It might be that your IDE doesn't understand the >> in your template specification. Older versions of the C++ standard required that you put a space in between each > as in > >, otherwise it could be confused with the right shift operator >>. So:

std::back_inserter<std::vector<float> >(model.chunks.back().vectices));

answered Aug 2, 2012 at 4:39

Greg Hewgill

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3 Comments

Cody Gray Over a year ago

Good theory, but he says it works with std::string in the last section of code, which includes the same >> sequence without spaces.

Greg Hewgill Over a year ago

Ah, true. Curious that. But surely it's an IDE-specific thing, because otherwise code with syntax errors can't "compile and run flawlessly".

luveti Over a year ago

Just added a space in between the >> and the error went away! Must of been the IDE. Thanks you guys, and thank you for replying so quickly!

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