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inputing a text file into an array

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Re: inputing a text file into an array

#11

Jan 27th, 2008

you don't need lines 25-29 to zero out the array. Do it when the array is declared, like this:
int matrix[101][5] = {0};
>>What alterations/additions do I make to the code to import the .txt file into the array?
Code that reads the text file. Start by deleting lines 1 to 3 -- al those files are obsolete in C++. Most likely all you need is this:

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

Next declare an ifstream object Then in a loop read the integers into the array. See Vernan's post #6 above, which is an example of how to read the file.

Last edited by Ancient Dragon; Jan 27th, 2008 at 6:09 pm.

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Re: inputing a text file into an array

#12

Jan 27th, 2008

Sadly, the c++ compiler i have to use at uni must use those headers, as it isn't a very new program. So I do have to use them

You say to declare an ifstream object and then in a loop, read the integers into an array.

I know this is what I must do, but this is the code I am struggling with... I've never come across any examples of this before. Could you possibly give me some brief code that will read the integers into the array?

Thanks for the help with zeroing, that worked a treat

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Re: inputing a text file into an array

#13

Jan 27th, 2008

So you do know that you have three columns? You don't know how many rows, but there are three columns? If you don't know how many columns, this won't work. If it's different from 3, change numCols. Anyway, here's a way to read it in:

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int numCols = 3;
int numRows = 0;
 
 
while (inFile >> matrix[numRows][0])
{
      printf ("%d\t", matrix[numRows][0]);
      for (j = 1; j < numCols; j++)
      {
          inFile >> matrix[numRows][j];
          printf ("%d\t", matrix[numRows][j]);
      }
      numRows++;
      printf ("\n");
}
 
inFile.close ();
int numCols = 3;
int numRows = 0;


while (inFile >> matrix[numRows][0])
{
      printf ("%d\t", matrix[numRows][0]);
      for (j = 1; j < numCols; j++)
      {
          inFile >> matrix[numRows][j];
          printf ("%d\t", matrix[numRows][j]);
      }
      numRows++;
      printf ("\n");
}

inFile.close ();

You have

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inFile.close ();
inFile.close ();

at the top before anything is read in, so you want to take that out. I think these lines are going to give you an error:

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printf("\t%d", matrix[i][1],k);
printf("\t%d", matrix[i][2],k);
printf("\t%d", matrix[i][1],k);
printf("\t%d", matrix[i][2],k);

You only have one "%d", but you have two parameters. I'd take the "k" parameter out.

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Re: inputing a text file into an array

#14

Jan 27th, 2008

That works perfectly, thank you so much!!

Ok, for my next question:

I want there to be three columns for the text file yes. HOWEVER, i want to have 2 further columns with empty data in them, ready to put calculations in. Is this possible?

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Re: inputing a text file into an array

#15

Jan 27th, 2008

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Originally Posted by andyg55

Sadly, the c++ compiler i have to use at uni must use those headers, as it isn't a very new program. So I do have to use them

Oh, that's unfortunate that your school is making you learn something that will never be used in the real world. We tossed out those compilers 15 years ago.

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Originally Posted by andyg55

I've never come across any examples of this before.

Well, then you didn't read the POST #6 very well, if at all, because it has exactly what you need.

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MY bad

#16

17 Hours Ago

Dunno what I was thinking at the time.. please forgive me.
'

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Originally Posted by Ancient Dragon

Cody: if you want to post code, that is ok, but please
Use code tags [code=c++] /* code goes here */ [/code]

Don't use ancient header files with .h extension

Don't use eof() as you did in line 12 because it doesn't work like that

>> This reads the text in as characters
Why? it could read into integer variables just as easy. By reading in as strings the strings have to be converted into ints before they can be used. That just extra unnecessary work.

Name: Cody Oebel
Place : San Antonio , TX.