Yes, local variables like that and pointers to them don't remain valid after the function call they exist inside returns. That it works at all is simply a coincidence. Make a few more function calls and the memory pointed to will probably be overwritten with garbage.
The compiler is probably warning you about this mistake, but as a warning, not an error.
You should pass a pointer to that function instead of getting one from it. Don't let it give you its local variables, give yours to it; perfectly valid when done before your function returns.
You could also use a static variable, like:
But this has several caveats. Static variables act like global variables; it will be pointing to the same pointer every time, so you can't keep the pointer around and expect the value to stay the same when other things use it. Also, this isn't thread-safe since multiple threads would be competing for the same variable. Probably best to pass a pointer.
Last edited by Corona688; 07-06-2010 at 07:04 PM..
hello all,
I tried a program on an array to intialise array elements from the standard input device.it is an integer array of 5 elements.but after entering the 4th element it throws a message called "Segmentation Fault" and returns to the command prompt without asking for the 5th element.
... (3 Replies)
I have written a program which takes a directory as command line arguments and displays all the dir and files in it.
I don't know why I have a problem with the /etc directory.It displays all the directories and files untill it reaches a sub directory called peers which is in /etc/ppp/peers.the... (4 Replies)
ive written my code in C for implementation of a simple lexical analyser using singly linked list hence am making use of dynamic allocation,but when run in linux it gives a segmentation fault is it cause of the malloc function that ive made use of????any suggestions as to what i could do???
thank... (8 Replies)
Hi ,
During execution a backup binary i get following error
"Program error 11 (Segmentation fault), saving core file in '/usr/datatools"
Riyaz (2 Replies)
Hi,
Why I don't receive a segmentation fault in the following sample.
int main(void)
{
char buff;
sprintf(buff,"Hello world");
printf("%s\n",buff);
}
If I define a buffer of 10 elements and I'm trying to put inside it twelve elements, Should I receive a sigsev... (22 Replies)
Hi,
While comparing primary key data of two tables thr bteq script I am getting this Error. This script is a shell script.
*** Error: The following error was encountered on the output file.
Script.sh: 3043492 Segmentation fault(coredump)
Please let me know how to get through it.
... (5 Replies)
I use a binary name (ie polo) it gets some parameter , so for debugging normally i do this :
i wrote script for watchdog my app (polo) and check every second if it's not running then start it , the problem is , if my app , remain in state of segmentation fault for a while (ie 15 ... (6 Replies)
this is a network programming code to run a rock paper scissors in a client and server.
I completed it and it was working without any error. After I added the findWinner function to the server code it starts giving me segmentation fault.
-the segmentation fault is fixed
Current problem -Also... (3 Replies)
I keep getting this fault on a lot of the codes I write, I'm not exactly sure why so I'd really appreciate it if someone could explain the idea to me.
For example this code
#include <stdio.h>
main()
{
unsigned long a=0;
unsigned long b=0;
int z;
{
printf("Enter two... (2 Replies)
Oddities with gcc, 2.95.3 for the AMIGA and 4.2.1 for MY current OSX 10.14.1...
I am creating a basic calculator for the AMIGA ADE *NIX emulator in C as it does not have one.
Below are two very condensed snippets of which I have added the results inside the each code section.
IMPORTANT!... (11 Replies)
Discussion started by: wisecracker
11 Replies
LEARN ABOUT ULTRIX
setjmp
setjmp(3) Library Functions Manual setjmp(3)Name
setjmp, longjmp - non-local goto
Syntax
#include <setjmp.h>
int setjmp (env)
jmp_buf env;
void longjmp (env, val)
jmp_buf env;
int val;
Description
The and functions help deal with errors and interrupts encountered in a low-level subroutine of a program.
The function saves its stack environment in env (whose type, jmp_buf, is defined in the <setjmp.h> header file) for later use by It returns
the value 0.
The function restores the environment saved by the last call of with the corresponding env argument. After finishes, program execution
continues as if the corresponding call of (which must not itself have returned in the interim) had just returned the value val. The func-
tion cannot cause to return the value 0. If is invoked with a second argument of 0, returns 1. At the time of the second return from all
accessible data have values as of the time is called. However, global variables have the expected values. For example, those as of the
time of the
Examples
#include <setjmp.h>
jmp_buf env;
int i = 0;
main ()
{
void exit();
if(setjmp(env) != 0) {
(void) printf("value of i on 2nd return from setjmp: %d0, i);
exit(0);
}
(void) printf("value of i on 1st return from setjmp: %d0, i);
i = 1;
g();
/*NOTREACHED*/
}
g()
{
longjmp(env, 1);
/*NOTREACHED*/
}
If the a.out resulting from this C language code is run, the output is as follows:
value of i on 1st return from setjmp:0
value of i on 2nd return from setjmp:1
Unexpected behavior occurs if is called without a previous call to or when the last such call was in a function which has since returned.
Restrictions
The values of the registers on the second return from are register values at the time of the first call to not those of the Thus, variables
in a given function can produce unexpected results in the presence of depending on whether they are register or stack variables.
See Alsosignal(2).
RISC setjmp(3)