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C++ - Difference between Vec definitions [closed]

asked 2016-10-31 23:09:26 -0500

skr_robo gravatar image

updated 2016-11-01 00:58:46 -0500

berak gravatar image

What is the difference between the definitions:

1) vector<Vec4i> lines and

2) Vec4i l

I found both these in the same code here. I am wondering if there is any difference between the both? If not why use the first format which is longer?

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Closed for the following reason the question is answered, right answer was accepted by skr_robo
close date 2016-11-04 15:30:58.387541

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answered 2016-11-01 01:12:00 -0500

berak gravatar image

1) a Vec4i is a struct holding 4 integers, you can access them using the [] operator, like in:

Vec4i l(1,2,3,4);   l[2] == 3;

2) a std::vector is a (template)container for various things.

in the houghlines example, each found line has 2 endpoints, they are kept in a Vec4i like (x1,y1, x2,y2). since the algorithm will find many lines, those are stored in a vector<Vec4i> lines, and you would access it with

lines[which_line][which_coordinate]
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So, this means lines is a vector which contains Vec4i objects?

skr_robo gravatar imageskr_robo ( 2016-11-01 21:51:37 -0500 )edit

exactly !

berak gravatar imageberak ( 2016-11-02 00:42:48 -0500 )edit

Thank You so much for the help.

skr_robo gravatar imageskr_robo ( 2016-11-04 15:30:47 -0500 )edit

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Asked: 2016-10-31 23:09:26 -0500

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Last updated: Nov 01 '16