[Resolved] Vector help

[dsheller]

               eANum[i] = hold[0];
               eAMass[i] = hold[1];
               eName[i] = hold[2];
               eSymbol[i] = hold[3];

In the above code eANum etc are string arrays and hold is a vector, I try to assign the array of strings to a vector element, however, when I run the executeable it crashes, and I know it is this part because I commented it out and it ran fine.

[PT Exorcist]

could u show the rest of the code?

[dsheller]

#include <fstream>
#include <conio.h>
#include <algorithm>	// container manipulation
#include <string>		// easy strings
#include <vector>		// growable array
#include <string>

using namespace std;

void split_string(const string &s, vector<string> & out, char split_at);

int main()
{

   string incoming;
   int search;

   string eANum[105];
   string eAMass[105];
   string eName[105];
   string eSymbol[105];
   vector<string> hold;

   int i;
   int j;
   int k;

   ifstream infile;

   infile.open("a:\\elemental.txt", ios::in);

   if (!infile)
   	{
      	cout << "Fatal Exception: File could not be opened." << endl
         	  << "Press any key to terminate...";
         while (!kbhit());
      }
   else
   	{
      	for (i = 0; i <= 104; i++)
         	{
               hold.resize(0);

      			infile >> incoming;

               split_string(incoming, hold, ';');

               eANum[i] == hold[0];
               eAMass[i] == hold[1];
               eName[i] == hold[2];
               eSymbol[i] == hold[3];
            }

      }

   cout << "Enter a way to search: " << endl
        << "1. Search by atomic number." << endl
        << "2. Search by atomic mass." << endl
        << "3. Search by element name." << endl
        << "4. Search by element symbol." << endl;

   cin >> j;

   if (j == 1)
   	{
      	cout << "Enter an atomic number to search for." << endl;
        cin >> search;
     }
   else if (j == 2)
   	{
      	cout << "Enter an atomic mass to search for." << endl;
        cin >> search;
     }
   else if (j == 3)
   	{
      	cout << "Enter an element name to search for." << endl;
        cin >> search;
     }
   else
   	{
      	cout << "enter an element symbol to search for." << endl;
        cin >> search;
    }
     
	

   return 0;
}

void split_string(const string &s, vector<string> & out, char split_at)
{
	// for searching the string
	string::const_iterator stay, run;
	// set stay to the start of the string
	stay = s.begin();
	// temporary
	string t;
	// loop run through the string, from front to back
	for(run=stay; run != s.end(); ++run)
	{
		// if encountered split char...
		if(*run == split_at)
		{
			// ...clear the temporary value...
			t = "";
			// (speeds it up a little)
			t.reserve(run-stay);
			// ..., copy current substring to temporary...
			t.append(stay, run);
			// ...and add it to the array.
			out.push_back(t);
			// Finally, let the next substring begin directly after the splitting char.
			stay = run+1;
		}
	}
	// same as above for the last piece (from last split char to end of string)
	t = "";
	t.reserve(run-stay);
	t.append(stay, run);
	out.push_back(t);
}

The split function is corned bee's function so I know that is not the problem.

[CornedBee]

eANum[i] == hold[0];
eAMass[i] == hold[1];
eName[i] == hold[2];
eSymbol[i] == hold[3];

should be

eANum[i] = hold[0];
eAMass[i] = hold[1];
eName[i] = hold[2];
eSymbol[i] = hold[3];

= is the assignment operator, == is the comparison operator.

[dsheller]

I tried that, but it still crashes, any ideas?

[CornedBee]

Where does it crash? Do you know how to use a debugger?

[dsheller]

I have no idea why exactly it crashes but I do know it is the piece of code I initially posted.

Edit:

When I attempted to debug it it pointed me to this line:

basic_string<charT, traits, Allocator> &
basic_string<charT, traits, Allocator>::operator= (
  const basic_string<charT, traits, Allocator>& str)
{
    str.pref()->addReference();   // This line
    pref()->unLink(alloc_);
    data_ = str.data_;
    return *this;
}

[Jop]

That's just the assignment operator for the standard string, so that's of no help since you already know that it crashes when you assign a certain value to one of those strings.

As CB said, try to use a debugger and check what the variables are and on exactely what line it crashes

[dsheller]

Alright I will give it a try.

[dsheller]

Well when I run debugger I get an error at the following line:

eAMass[i] = hold[1];

Also, when I do something like this:

               eANum[i] = hold[0];
               cout << "Got to step 1\n";
               eAMass[i] = hold[1];
               cout << "Got to step 2\n";
               eName[i] = hold[2];
               cout << "Got to step 3\n";
               eSymbol[i] = hold[3];
               cout << "Got to step 4\n";

It prints the "Got to step 1" line and then it crashes. So I think that after it first assigns to eANum it crashes.

[Jop]

eAMass[i] == hold[1];

Are you sure there's a second element in the vector hold?

The error is not at eANum since it does print got to step 1

Also try to check what hold[1] contains when you try to add it to the string!

[dsheller]

Yea this c++ business really frys my brain in VB I would have had this solved so fast. I will continue to try.

[dsheller]

Well I am sure that it is filling the vector correctly because I tested it out without the loop and everything and it printed the entire file split at the semi-colon

[Jop]

Yeah but it's not the prob at the first item of the vector, it occurs at the second (or have you used without the loop while accessing hold[1] ? )

Also can you maybe attach the file you're trying to read? So that we can test it over here and see what the prob is?

[dsheller]

Alright I will attach it, however, I think there is something weird going on because when I split it and read through each item in the vector it works fine but then assigning doesnt.

[Jop]

Tried it here, runs without any crashes / runtime errors... what compiler are you using?

also:

   if (!infile)
   	{
      	cout << "Fatal Exception: File could not be opened." << endl
         	  << "Press any key to terminate...";
         while (!kbhit());
         return 1
      }

You'd want the code to terminate

And I recommend not to use conio.h, include <iostream> (for cin and cout) and use

system("pause");

instead of

while (!kbhit());

And consider using a switch statement rather than your if - elseif

[dsheller]

I have no idea how you did that, but wow, thanks , I mean, it looks exactly like my old code in most respects I can't even find the major difference!

[dsheller]

Sorry to burden you again, but say I want to search through and compare a string to a float value, how would I go about converting the string to float? I tried using atof but I didn't have much luck (errors).

[Jop]

Something like this?

int main()
{
string s = "1.007";
float f = atof(s.c_str());
cout << f;
}

[dsheller]

I got it to work, I just decided to change the search variable to a string rahter than having it a float =/