initialize a vector pf points in C++

Question

Point P0(0,0), P1(3, 4), P2(-50,-3), P3(2,0); //Input Points (fine) std::vector<Point> Points(P0,P1, P2 ,P3); (not fine)

This does not seem to work. How do I initialize points vector to the values above? Or is there an easier way to do this?

You might want to check stackoverflow.com/questions/2236197/… — Tony Delroy
– Tony Delroy, Commented Mar 4, 2014 at 0:12

Red Alert · Accepted Answer · 2014-03-03 23:38:06Z

5

If you are using c++11, you can use braces to declare vectors inline.

std::vector<Point> Points {P0, P1, P2, P3};

answered Mar 3, 2014 at 23:38

Red Alert

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4 Comments

Programmer Over a year ago

unfortunately, i do not have c++11

Programmer Over a year ago

i got it.. data.push_back(Point(1,1));

Red Alert Over a year ago

Then you'll have to add them separately. You probably do have c++11 though, unless you are using an ancient compiler.

Andrew Lazarus Over a year ago

Helpful link about VS and C++ 11

Spomky-Labs · Accepted Answer · 2014-03-03 23:41:31Z

Try the following code (not tested):

Point P0(0,0), P1(3, 4), P2(-50,-3), P3(2,0); //Input Points (fine) std::vector<Point> Points; Points.push_back(P0); Points.push_back(P1); Points.push_back(P2); Points.push_back(P3);

Vlad from Moscow · Accepted Answer · 2014-03-04 00:06:44Z

There is no need to define objects of type Point that to define the vector. You could write

std::vector<Point> Points{ { 0, 0 }, { 3, 4 }, { -50,-3 }, { 2, 0 } };

provided that your compiler supports the brace initialization. Or you could define an array of Point and use it to initialize the vector. For example

#include <vector> #include <iterator> //,,, Point a[] = { Point( 0, 0 ), Point( 3, 4 ), Point( -50,-3 ), Point( 2, 0 ) }; std::vector<Point> Points( std::begin( a ), std::end( a ) ) ;

This code will be compiled by MS VC++ 2010.

Brace-enclosed initializer lists and std::begin and std::end are all features of C++11 which may not be fully supported in older compilers.
@Edward I wrote clear that MS VC++ 2010 supports the last example in my post.
indeed you did. I was adding to your answer by naming the specification which added these features to the language so that others with different compilers will be able to understand what they need to be able to make use of your answer.

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