class std::vector<...> has no member named

Question

I'm pretty new to C++, and I'm trying to use a vector of structs, but I keep getting "class std::vector’ has no member named ‘p’" when I try to compile my code. This is it, by the way:

#include <vector>
#include <cstdlib>
#include <stdio.h>
#include <algorithm>
using namespace std;

struct animal {
    int p;
    int v;
};


bool cmpp (animal a, animal b) { 
    return (a.p < b.p); 
}

bool cmpv (animal a, animal b) { 
    return (a.v < b.v); 
}

bool cmpc (pair<animal, animal> a, pair<animal, animal> b) { 
    return (a.first.p < b.first.p); 
}

int main(){
    int c, s;
    while(scanf("%d %d", &c, &s) != EOF){
        vector<animal> masses[2*c];
        vector<pair<animal, animal> > chamber;

        for (int i = 0; i < 2*c-s; i++){
            masses[i].v = 0;
            masses[i].p = -1;
        }

        for (int i = 2*c-s; i < 2*c; i++){
            masses[i].v << cin;
            masses[i].p << i - 2*c-s;
        }

        sort(masses.begin(), masses.end(), cmpv);

        for(int i = 0; i < c; i++){
            if(chamber[i].p < masses[2*c-i] && chamber[i].p != -1)
                chamber[i] = pair<animal, animal> (masses[i], masses[2*c-i]);
            else
                chamber[i] = pair<animal, animal> (masses[2*c-i], masses[i]);
        }

        sort(chamber.begin(), chamber.end(), cmpc);

        for(int i = 0; i < c; i++){
            printf("%d %d", chamber[i].first.v, chamber[i].second.v)
        }
    }
    return 0;
}

There might be other errors in the code, but I just wanna know the vector thing for now. P.S.: This is my first question here :) I knew this day would come!

Solution 1

You have an array of vectors for some reason.

vector<animal> masses[2*c];

should probably be

vector<animal> masses(2*c);

Solution 2

Here are the ways to defining and initializing vector:

vector<T> v;//empty

vector<T> v1(v2);//v1 is a copy of v2
vector<T> v1 = v2;

vector<T> v1{a, b, c};//list initialize 
vector<T> v1 = {a, b, c};

vector<T> v(b, e);// v is a copy of the elements in the range denoted by iterators b and e

vector<T> v(n);//v has n value-initialized elements
vector<T> v(n, t);// v has n elements with value t

So, your defining doesn't do what you want,

vector<animal> masses[2*c]; //masses is an array of vector<animal>

when you say masses[i] which is a vector not animal, has no member named ‘p’
You should write:

vector<animal> masses(2*c);