how to iterate over col in 2D vector c++? - c++

Question

I have the following vector of vector containning tree string elements, I want to know how to iterate over col element instead of normal loop over rows
vector<vector<string>> vec2Dstr =
{
{ "A2", "A4", "A6" },
{ "B2", "B4", "B6" },
{ "C2", "C4", "C6" },
{ "D2", "D4", "D6" },
{ "E2", "E4", "E6" }
};
the output expected is :
A2 B2 C2 D2 E2
A4 B4 C4 D4 E4
A6 B6 C6 D6 E6
code
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
vector<vector<string>> vec2Dstr =
{
{ "A2", "A4", "A6" },
{ "B2", "B4", "B6" },
{ "C2", "C4", "C6" },
{ "D2", "D4", "D6" },
{ "E2", "E4", "E6" }
};
for(auto & j : vec2Dstr ) {
for(int i = 0 ; i < 3; i++ )
cout << " => " <<j.at(i) << endl;
}
return 0;
}

Answer 1

this following code might do the aim expected!
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
vector<vector<string>> vec2Dstr =
{
{ "A2", "A4", "A6" },
{ "B2", "B4", "B6" },
{ "C2", "C4", "C6" },
{ "D2", "D4", "D6" },
{ "E2", "E4", "E6" }
};
size_t total_col = vec2Dstr[0].size();
for (int col=0; col<total_col; ++col)
{
for(auto& row : vec2Dstr)
{
cout << row[col] << " ";
}
cout << endl;
}
return 0;
}

Answer 2

Your for loops are wrong. How do you expect it to show 5 elements when you hardcode a limit of 3. Rewrite the for loop using this logic:
Iterate vec2Dstr from 0 to length.
Display vec2Dstr[i][j] where j increases after each loop we described above.
If you still are stuck after this let me know. Show me some code first.