generating an array of arrays

[djm]

Good day,

I am attempting to generate an array of arrays. The code compiles but hangs when I run it (suggesting an infinite loop perhaps?). I am unsure how code would be necessary for a wise and kind :) person to help me, but I have included what I deemed necessary.

Thank you

#include <iostream>
#include <fstream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <stdio.h>
#include <cstdlib>
#include <ctype.h>
 
using namespace std;
 
int main (){
 

Skip opening and reading in initial data and finding distances between points (sab_array and tab_array).
These sections work correctly.

nsteps and narray are previously entered constants.

Here is where I am trying to generate the array of arrays.

  vector<double> tsab_array;
  for(int j=0; j<narray;j++)
    {
      for(int i=1; i=nsteps; i++)
    {
    double tsab = (1-1/i)*sab_array[j] - i*(tab_array[j]);
    tsab_array.push_back(tsab);
    }
    }
  for(vector<double>::iterator v=tsab_array.begin(); v != tsab_array.end(); v++)
    {
      cout<<*v<<"\n";
    }
 
  return 0;
}
 

[D_C]

In the second for loop, you should be testing i != nsteps instead of assigning i = nsteps.

[Banfa]

D_C is right also even if you correct that unless you are sure that nsteps >= 1 then you might get what appears to be an infinite loop because it can take a long time to count to 2^32 if you have 32 bit ints.

This is why it is often better not to compare to a single value in a for loop but to compare to the end of a range, i.e. rather than i != nsteps use i < nsteps.

Finally I see no construct in your code that could be interpreted as an array of arrays, tsab_array is just an array of double


This calculation

(1-1/i)*sab_array[j] - i*(tab_array[j])

has a slightly odd effect, for any given j if i ranges between 1 and 4 then I think it will issue the values

-tab_array[j]
sab_array[j] - 2*tab_array[j]
sab_array[j] - 3*tab_array[j]
sab_array[j] - 4*tab_array[j]

is this the output you required?