CODEWITHSUNDEEP
c++c++11
Idea
Idea

Reputation: 25

vector<pair<double,double>> giving problems

#include <iostream>
#include <string>
#include <vector>

using namespace std;

typedef vector<pair<double, double> > Vec; //cords vector (0.0,0.0)/(x,y)
typedef pair<double, double> Punto; //single coord

int main()
{
    int x;
    cout << "cuants vertex?" << endl;
    cin >> x;
    Vec V[x]; // Declare vector of pairs as long as user wants
    Punto P;
    for (int i = 0; i < V.size(); i++) { //fill vector with coords
        cout << "Introdueix coordenada numero: " << i;
        cout << "x: ";
        cin >> P.first;
        cout << "y: ";
        cin >> P.second;
        V.push_back(P);
    }
    for (int c = 0; c < V.size(); c++) { //show all coords
        P.first = V[c].first;
        P.second = V[c].second;
        cout << P.first << P.second << endl;
    }
}

This is a simple code filling a vector<pair<double,double>>, it gives this errors:

main.cpp: In function ‘int main()’:
main.cpp:16:18: error: request for member ‘size’ in ‘V’, which is of non-class type ‘Vec [x] {aka std::vector > [x]}’
   for(int i=0;i<V.size(); i++){
                   ^~~~
main.cpp:19:5: error: request for member ‘push_back’ in ‘V’, which is of non-class type ‘Vec [x] {aka std::vector > [x]}’
    V.push_back(P);
      ^~~~~~~~~
main.cpp:21:19: error: request for member ‘size’ in ‘V’, which is of non-class type ‘Vec [x] {aka std::vector > [x]}’  
for(int c=0; c<V.size(); c++){
                 ^~~~
main.cpp:22:16: error: ‘Vec {aka class std::vector >}’ has no member named ‘first’
    P.first=V[c].first;
                 ^~~~~
main.cpp:23:17: error: ‘Vec {aka class std::vector >}’ has no member named ‘second’; did you mean ‘end’?   
P.second=V[c].second;
              ^~~~~~

Any way to solve it?

Upvotes: 1

Views: 1085

Answers (2)

L. F.
L. F.

Reputation: 20579

Vec V[x];

x is not a constant expression, so you are declaring a variable-length array. This is a compiler extension and is not C++. And an array cannot have .size() member.

You need to change it to:

Vec V;

(Also, use Vec::size_type to go through the vector, or you will get a signedness warning.)

Upvotes: 1

iz_
iz_

Reputation: 16593

This line:

Vec V[x]; // Declare vector of pairs as long as user wants

Is actually creating a C-style array of Vec, not a single Vec. You should use round parentheses instead, constructing a single Vec:

Vec V(x); // Declare vector of pairs as long as user wants

However, now push_back will add additional elements. Replace

V.push_back(P);

with

V[i] = P;

Upvotes: 5

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