How to combine structures and vectors?

[Auroch]

I have the next problem:
Entering coordinates of points on a plain with keyboard (as rows x,y). Replacing coordinates in vector (point - structure data type). Than calculating distance from the first point to all another points.

What I can do after creating structure of points?

  struct points{  
    float x;
    float y;
  };

[keskiverto]

Struct is a type definition.

std::vector<points> z; 'z' is an object, whose type is a vector of points. It has no points in it yet.

Read input. For each row append a new point to the vector.

[Auroch]

Hi! How to add a point from structure to vector?

[TwilightSpectre]

If you have your structure points, the easiest and most common way is to create an instance of the struct, and then use push_back to add it to the vector, e.g.:

struct points {
    float x;
    float y;
};

//...

std::vector<points> pointvec;
points p;
p.x = 5.0f;
p.y = 3.6f;
pointvec.push_back(p); // add 'p' to the vector 

[Auroch]

Thank you very much. And what are 5.0f /* and */ 3.6f

 
points p;
p.x = 5.0f;
p.y = 3.6f;

[TwilightSpectre]

Ah, adding the 'f' at the end of a number just says that it is a floating point number, rather than a double. Doesn't really make a difference, just makes things clearer for me when I'm dealing with floats rather than doubles.

[Auroch]

OK, but I should enter coordinates with keyboard. How can I do it?

[TwilightSpectre]

Just the same way as you would normally: Input into the structure. Do you know how you do that? Here is an example:

struct myStruct {
    float a;
};

// ...

myStruct s;
std::cin >> s.a;

[keskiverto]

http://www.cplusplus.com/articles/386AC542/
http://www.cplusplus.com/doc/tutorial/basic_io/

while ( std::cin >> p.x >> p.y )
{
 // append to vector
}

[Auroch]

Entering two coordinates (x,y) is the next code?

struct points {
    float x, y;
};

// ...

points p;
std::cin >> p.x >> p.y;

or?

struct points {
    float x;
    float y;
};

// ...

points p;
std::cin >> p.x;
std::cin >> p.y;

[TwilightSpectre]

Yes - either work. Also, see @keskiverto's response for one example of how you might add values to a vector.

[Auroch]

Thank you so much! Very helpful! :D