Reading a .txt file into an array

[randallson88]

I am writing a program in Dev C++ to read values from a .txt file into a series of arrays. The program I have written so far compiles and starts to run, but on the output some of the values are wrong, and after several lines the programs crashes. I attempted to debug it, and the compiler suggests that the problem might be where I am reading the file into the program, but I can't figure it out.

Here is my program:

#include<iostream>
#include<math.h>
#include<iomanip>
#include<fstream>
#include<string>

using namespace std;

int main(void){

    string fileName=" ";
    ifstream file;
    int rows(0), termsOne[rows], termsTwo[rows], columns(0), limitOne(0); 
    int limitTwo(0), i(0);
    double valueX[rows], sinX[rows], sinOne[rows], errorOne[rows];
    double sinTwo[rows], errorTwo[rows];
    
    cout<<"filename?  >>  ";
    cin>>fileName;
    
    file.open(fileName.c_str());
    
    if(file.fail())
        cout<<"File did not open properly.";
        
    file>>rows>>columns>>limitOne>>limitTwo;
    
    for(i=0;i<rows;i++){
         file>>valueX[i]>>sinX[i]>>sinOne[i]>>termsOne[i]>>errorOne[i]
         >>sinTwo[i]>>termsTwo[i]>>errorTwo[i];//I think the problem is here

         cout<<valueX[i]<<"  "<<sinX[i]<<"  "<<sinOne[i]<<"  "
         <<termsOne[i]<<"  "<<errorOne[i]<<"  "<<sinTwo[i]
         <<"  "<<termsTwo[i]<<"  "<<errorTwo[i]<<endl;
    }
    
    system("pause");
    file.close();
    return(0);
    
}

The file I am trying to read in has 4 numbers on the first row and 8 numbers on each row after that(it is a table of values comparing sin(x) to a taylor series expansion).

[hanst99]

Dev C++ is evil (I am so tired of saying this all the time -__-)

What does your actual file look like?

(Unrelated: Does anyone know if fstream will gets a std::string overload for open in 0x? If feels wrong for a C++ class to require a cstring...)

EDIT: Ah no wait, this is actually pretty easy:

Your arrays all have 0 elements, you seg fault when you try to access them, because you only change row afterwards.

[coder777]

line 13 does normally not compile. Anyway 'termsOne' (and following) is an array of size 0 and does not expand even if you change 'rows'. Use dynamic arrays like std::vector instead


http://www.cplusplus.com/reference/stl/vector/

[randallson88]

I declared the arrays after the value for rows and now it works thank you so much.