Thread: what is segmentation fault?

What does segmentation fault mean?

Why when i run the following code, there is a segmentation fault?:

Code:

#include <string.h>
#include<iostream.h>
#include<fstream.h>
#include<ctype.h>
#include"lvp/vector.h"
int main()
{
//      const int BUFF_SIZE=100000;
        const long long BUFF_SIZE = 1000000;
        int a;
        ifstream infile;
        ofstream outfile;
        char buff[BUFF_SIZE];
// open the files
//      infile.open("/misc/tmp/kddcup.data_10_percent.fresh");
        infile.open("data.txt");
        outfile.open("output.txt");
// make sure the files are open
        if(!infile.is_open()){
                cerr << "error opening input file";
                return 1;
        }
        if(!outfile.is_open()){
                cerr << "error opening output file";
                return 1;
        }
// loop until the end of the input file
        for(a=0; !infile.eof();){
// read in one line
                char *p;
                char word[20] = "";
                infile.getline(buff,200);
//              infile.ignore(1);
                p = strtok(buff,",");
                for(int i=0; i<42; i++)
                {
                        if(i==1)
                        {
                                strcpy(word,p);
                                cout<<word<<endl;
                                outfile << word << endl;
                        }
                        if(i==2)
                        {
                                strcpy(word,p);
                                cout<<word<<endl;
                                outfile << word << endl;
                        }
                        if(i==3)
                        {
                                strcpy(word,p);
                                cout<<word<<endl;
                                outfile << word << endl;
                        }
                        if(i==41)
                        {
                                strcpy(word,p);
                                cout<<word<<endl;
                                outfile << word << endl;
                        }
                        p = strtok(NULL,",");
                }
        }

// close the files
        infile.close();
        outfile.close();
// pause so you can see the output on the screen
        cout << " **** All done! ****\n";
        cin.get();
        return 0;
}

Thanks for response,

~D

>p = strtok(buff,",");
>p = strtok(NULL,",");
strtok will return NULL when it doesn't find what it's looking for. You must check for p not being null before you attempt to use it.
This could well be the cause of your problem.

>strcpy(word,p);
Try using strncpy() to be on the safe side.

Another thought, though I'm not pre-empting correlcj and Hammer. (Actually, I like their possible solutions. ).

Try decreasing BUFF_SIZE and see if your code will compile.

My compilers (Borland) tend to be more specific (if sometimes indecipherable) with their error messages.

Actually, it appears that you're attempting to create arrays that are too large. Borland allows up to 64K (140K when the "modifier" huge is used).

Code:

int huge arr[70000L];  /* Allocate 140,000 bytes */

You're at 1Mb (almost). Just a thought.

-Skipper

Also you might try changing this:

Code:

// loop until the end of the input file
        for(a=0; !infile.eof();){
// read in one line
                char *p;
                char word[20] = "";
                infile.getline(buff,200);

To this:

Code:

// loop until the end of the input file
        while (infile.getline(buff,200)){
// read in one line
                char *p;
                char word[20] = "";