Help me debug?

[Em7add11]

So, I'm working on a program that compiles fine but gives this message when run:

jfarthing@em7add11 # ./a.out
Segmentation Fault

jfarthing@em7add11 #



Anybody want to offer some advice?

[themuzicman]

You have a bug in your program.






OK...

http://www.cs.bu.edu/help/unix/segmentation_fault.html

A segmentation fault occurs when your program tries to access memory locations that haven't been allocated for the program's use. canf("%d", number);

In this case, number is integer. scanf() expects you to pass it the address of the variable you want to read an integer into. But, the writer has fogotten to use the `&' before number to give scanf the address of the variable. If the value of number happened to be 3, scanf() would try to access memory location 3, which is not accessible by normal users. The correct way to access the address of number would be to place a `&' (ampersand) before number:

scanf("%d", &number);

Another common segmentation fault occurs when you try to access an array index which is out of range. Let's say you set up an array of integers:

int integers[80];

If, in your program, you try to use an index (the number within the brackets) over 79, you will ``step out of your memory bounds'', which causes a segmentation fault. To correct this, rethink your array bounds or the code that is using the array.

© source where applicable

Not sure if you're using memory pointers or what, but I think it usually has to do with accessing uninitialized variables or using variables improperly, as in the example above

Michael

[Em7add11]

Here's my source:

#include <stdio.h>

int main() {
    printf("Segmentation Fault\n");
    return 1;
}

See anything that resembles what that article describes?

[themuzicman]

Just the author of the program.

(Who will now be segmented. DEVELOPERS! oy!)

[Sheepdog]

seg faults are evil, evil little errors.

[$cirisme]

Here's my source:

#include <stdio.h>

int main() {
    printf("Segmentation Fault\n");
    return 1;
}

See anything that resembles what that article describes?

[lee_merrill]

<!-- No comment? -->

<!-- Actually, this really isn't a comment! -->

And it's all the segment's fault!

The BSD demon made me do it...

Blessings,
Lee

[NeilUnreal]

It's like the apocryphal tape backup restore source code:

#include <stdio.h>

int main () 
{
    printf ("Cannot read tape.");

    return -1;
}

[themuzicman]

select * from developers where developers = TRUE

no rows returned

[{Tim}]

It's like the apocryphal tape backup restore source code:

#include <stdio.h>

int main () 
{
    printf ("Cannot read tape.");

    return -1;
}

Or my personal favourite... (forgive the BASIC )

PRINT "WARNING! ALL DATA ON NON-REMOVEABLE"
PRINT "DRIVE C: WILL BE LOST! PROCEED? (Y/N)";

do:loop until InKey$<>""

PRINT "Y"
PRINT
PRINT "Formatting..."

[NeilUnreal]

Or my personal favourite...

When you implement a Twain scanner driver, a common place to start is with the Twain default library. One of the fall-back error messages in that library reads something like:

"Sorry, detailed error status returned success."

(In other words, it succeeded in returning a fatal error, )

And I've actually seen it show up at the user interface level from at least one commercial scanner driver.

-Neil

[lee_merrill]

We have a product that says, erm, "Press enter to exit"...

Blessings,
Lee

[Sheepdog]

there'e always the ubiquoitous "Keyboard not found. Press F1 to continue"

[lee_merrill]

Maybe by the F1 button they mean the belly button on the front of the computer?

Blessings,
Lee

[Barry Desborough]

So, I'm working on a program that compiles fine but gives this message when run:

jfarthing@em7add11 # ./a.out
Segmentation Fault

jfarthing@em7add11 #



Anybody want to offer some advice?

You're not null-terminating your string?