CODEWITHSUNDEEP
c++for-loopvectorstructdisp
user147813
user147813

Reputation: 67

Access vector outside of for-loop C++

I can show the values stored in vector mem (see edited code). How can i store the values in vec.name? It's the syntax that i have problem with. Specifically defining the container for vec.name as well as storing data in it using push_back. 

    #include <vector>
    #include <iostream>
    #include <fstream>
    #include <cmath>
    #include <cstdlib>
    #include <set>

    using namespace std;

    //struct vec {  
    //  int name; 
    //};

    //vector<vec> mem;
    vector<int> mem;    
    size_t nx, ny, nz;

    void read(const char * name)
    {
        ifstream file(name);
        cout << "read file " << name << endl;
        size_t Nx, Ny, Nz;
        file >> Nx >> Ny >> Nz;
        int c=0;
        size_t itens;

        for (size_t z = 0 ; z < Nz ; ++z) { 
            for (size_t y = 0 ; y < Ny ; ++y) {
                for (size_t x = 0 ; x < Nx ; ++x) {
                    c=c+1;
                    file >> itens;                 
                        //mem[c].name = itens;
                        mem.push_back(itens);

                }
            }       
        }
    }



    int main ()
    {

        read("names.txt");
        for(int i=0;i<26;i++){
        cout << mem[i] <<endl;
        }
        cout << "Computation done." << endl;
        return 0;

    }

Upvotes: -4

Views: 324

Answers (1)

Igor
Igor

Reputation: 27250

Update following your comment and your Edit:

You are getting a Segmentation Fault on the first time you are on the line mem[c].name = itens; because you are trying to access mem[1] which you haven't created. In order to access an element of a vector you need to add it to a vector, usually using push_back. Since you are trying to access the second element of the vector, you should call push_back at least twice beforehand.

You probably also need to do some additional fixes in your algorithm, but I will leave it to you.

My original answer:

Your container is vector<vec> name. You can access its n'th element by name[n]. You can access n'th element's mm member variable by name[n].mm

The code that you are using in your snippet (vec[c].name) is wrong.

Upvotes: 2

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