What does the '?' means in C++?

What does the '?' means in C++?

I´m developing in C++ and I've downloaded a source code from a web, but
analyzing it I've found and structure that I can´t understand...
This is the code:
CvSeq* objects = cvHaarDetectObjects( img, cascade, storage, 1.1, 4, 0,
cvSize( 40, 50 ));
CvRect* r;
// Loop through objects and draw boxes
for( int i = 0; i < (objects ? objects->total : 0 ); i++ ){
r = ( CvRect* )cvGetSeqElem( objects, i );
cvRectangle( img, cvPoint( r->x, r->y ), cvPoint( r->x + r->width,
r->y + r->height ),
colors[i%8]);
}
Inside the 'for' loop it has an structure as delimiter that I can´t
understand, I don´t know how '?' works :(...
Any idea? Thanks for all :)!