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Files and Arrays
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Join Date: Jun 2008
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Junior Poster in Training
When I run this program I can only access the first row of data. Can any one help so that I can access all the lines? I am trying to store numbers into a 2-dimensional array.
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
int main ()
{
ifstream inData;
float numbers[25][10];
int rows=0,cols;
inData.open("data.txt");
while (inData){
for (rows=0; rows<=7; rows++){
for (cols=0; cols<=7; cols++)
{
inData >> numbers[rows][cols];
cout<<fixed<<showpoint<<setprecision(1)<<numbers[rows][cols]<<" ";
}
cout<<endl;
}
}
cout<<endl;
cout<<fixed<<showpoint<<setprecision(1)<<numbers[0][1];
return 0;
} Last edited by JackDurden; Jul 28th, 2008 at 10:19 pm.
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Join Date: Aug 2005
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How about this one? But this has the danget of writing outside the bounds of the array, so you need to add more checkiing.
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Join Date: Oct 2007
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Posting Whiz in Training
It looks like you have declared an array of 25 rows and 10 columns. I'd suggest you intialize the rows to their value(rows=25) and columns (cols=10). Try my example
dont forget to declare your array numbers[rows][cols]
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Last edited by joshmo; Jul 29th, 2008 at 4:42 am.
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Junior Poster in Training
That seems to have done it! Thanks for the help!
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>> for (i=0; i<=rows; i++)
I hope you realize that is going to cause data overflow errors which might possibly crash your program or destroy other parts of your program if that code is incorporated into a larger program. Why? Because the loop performs one too many iterations -- if the value of rows is 25 then the above loop will count from 0 to 26, which is one too many. Same with the inner j loop.
What you want is this:
Then there is the danger that the data file doesn't contain that many numbers (rows * columns).
I hope you realize that is going to cause data overflow errors which might possibly crash your program or destroy other parts of your program if that code is incorporated into a larger program. Why? Because the loop performs one too many iterations -- if the value of rows is 25 then the above loop will count from 0 to 26, which is one too many. Same with the inner j loop.
What you want is this:
for (i=0; i < rows; i++) Then there is the danger that the data file doesn't contain that many numbers (rows * columns).
Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.
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Posting Whiz in Training
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Originally Posted by Ancient Dragon 
>> for (i=0; i<=rows; i++)
I hope you realize that is going to cause data overflow errors which might possibly crash your program or destroy other parts of your program if that code is incorporated into a larger program. Why? Because the loop performs one too many iterations -- if the value of rows is 25 then the above loop will count from 0 to 26, which is one too many. Same with the inner j loop.
What you want is this:
for (i=0; i < rows; i++)
Then there is the danger that the data file doesn't contain that many numbers (rows * columns).
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