CODEWITHSUNDEEP
cnetbeans
user266425
user266425

Reputation:

Netbeans and C, peculiar bug

I am writing something in C using Netbeans 6.9.1 (its a requirement) and I stumbled upon a peculiar bug. When I try to run this code from Netbeans:

#include <stdio.h>
#include <stdlib.h>
#include "company_description.h"


company_description read_company_description() {
    char file_name[FILE_NAME_BUFFER_SIZE];
    FILE *company_description_file;
    company_description cd;


    printf("Please enter the name of the file containing the "
            "company's description: \n");
    scanf("%50s", file_name);


    company_description_file = fopen(file_name, "r");
    if(company_description_file != NULL) {
        printf("file is not null\n");
    }
    fscanf(company_description_file, "%s%s%s%s%s%s", cd.company_name,
        cd.name_file_deliveries_info, cd.name_file_industrial_park,
        cd.name_file_places, cd.name_file_roads, cd.name_file_vans_info);
    return cd;
}

I get this output:

Please enter the name of the file containing the company's description: 
name_file.txt
Segmentation fault
Press [Enter] to close the terminal ...

Ok I say to myself, from my point of vie there is nothing wrong with this code and I go to ~/path/to/NetbeansProject/dist/Debug/GNU-Linux-x86 and try to run the executable from there and it works. I forgot to mention that the file that should be read is in that same folder, exactly where the executable is. Now there might be a mistake on my side but I don't see it so any thoughts about this would be helpful. Thanks!

Upvotes: 0

Views: 397

Answers (3)

Karel Petranek
Karel Petranek

Reputation: 15164

Don't blame the compiler/IDE, the bug is in your code :)

company_description_file = fopen(file_name, "r");
if(company_description_file != NULL) {
    printf("file is not null\n");
}
fscanf(...

There is an else missing that will cope with the situation when the file is not found. Right now you pass a NULL pointer to fscanf which causes the crash. Your program cannot find the file most probably because NetBeans sets the working directory somewhere else. Make sure you set the correct working directory or copy the input file to the proper location.

Upvotes: 0

wkl
wkl

Reputation: 79981

As to why it doesn't run in Netbeans: working directory is probably incorrect - when you run from Netbeans, the working directory is not necessarily the same as where the executable resides.

I do not have Netbeans installed, but you can set the working directory (what directory the system thinks the executable was executed in) in your project's settings.

I also agree with aschelper's answer - if you don't get a valid FILE * back you don't want to continue running that file code.

Upvotes: 1

aschepler
aschepler

Reputation: 72421

Your code will probably crash if fopen fails. Sure, you have a check for whether company_description_file != NULL, but then if it is null you go ahead and pass it to fscanf anyway (rather than exit()ing or returning early or something). Undefined Behavior.

Upvotes: 1

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