CODEWITHSUNDEEP
c++vectoriterator
Jack
Jack

Reputation: 271

iterate through an array of vector in c++

I am trying to iterate through my vector array, but I cannot seem to get it to work, my error is at the second for loop and the error message is the follow:

expected primary expression before 'double'

I have looked through on how to iterate a regular vector, but how do I iterator a vector array? I followed this structure:

#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector;
  for (int i=1; i<=5; i++) myvector.push_back(i);

  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it = myvector.begin() ; it != myvector.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

I can't seem to get my vector array version to work. 

#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

int main(int arc, char *argv[])
{
   vector<double> vector[7];

   double num[7];
   ifstream infile("data.txt"); 
   string temp;

   for(int i = 0; i <= 6; i++)
   {
      infile >> temp;
      cout << temp << ' ';
   }
   cout << endl;

   while(infile >> num[0] >> num[1] >> num[2] >> num[3] >> num[4] >> num[5] >> num[6])
   {
      for(int i = 0; i <= 6; i++)
      {
         vector[i].push_back(num[i]);
      }
   }
   cout << endl;

   for(int i = 0; i <= 6; i++)
   {
      // error on this line
      // not sure what is wrong before vector<double>:: iterator it = vector[i].begin()
      for(vector<double>::iterator it = vector[i].begin(); it != vector[i].end(); ++it)
      {
         cout << ' ' << *it;
      }
   }
   return 0;
}

Upvotes: 0

Views: 5677

Answers (3)

Ben Voigt
Ben Voigt

Reputation: 283624

On this line of code

for(vector<double>::iterator it = vector[i].begin(); it != vector[i].end(); ++it)

vector is not a type, it's a variable. Names in local scopes hide names in global scopes.

You could instead write

for(::std::vector<double>::iterator it = vector[i].begin(); it != vector[i].end(); ++it)

or

for(auto it = vector[i].begin(); it != vector[i].end(); ++it)

but a better solution is to not use the same name for multiple different things.

Upvotes: 2

legends2k
legends2k

Reputation: 32884

#include <iostream>
#include <fstream>
#include <vector>

using std::ifstream;
using std::vector;
using std::cout;

int main(int arc, char *argv[])
{
   const size_t data_size = 7;
   ifstream infile("data.txt"); 
   vector<double> input;
   double num;
   while ((infile >> num) && (input.size() <= data_size))
   {
      input.push_back(num);
   }
   for (vector<double>::iterator it = input.begin(); it != input.end(); ++it)
   {
      cout << ' ' << *it;
   }
   return 0;
}

Use minimal variables and get the job one. Also don't name your variables after standard library functions, classes, structs, etc. and avoid using directives like using namespace std; and prefer using declarations.

Upvotes: 1

Taimour
Taimour

Reputation: 129

You can simply traverse a vector of array like this for (int i=0; i<myvector.size(); i++) { for (int j=0; j<myvector.size(); j++) { cout<<myvector[i][j]<<endl; } }

Upvotes: -1

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