I have to create static 3D array 200x200x200, but when I try to compile this code
int main()
{
int arr[200][200][200];
return 0;
}
program crashes. Debugger displays this error:
Program received signal SIGSEGV, Segmentation fault.
Does anyone have idea how to solve this?
You are running out of space: 200*200*200*4(32 bit system int) are ~32MB. You cannot allocate that much space in the stack. Answer 1 and Answer 2
Find another solution that involves computing less numbers, for example using temporal results to find other results, or saving values to file and loading them when needed
Related
Hi I am doing this simple program
#include <iostream>
#include <string>
using namespace std;
int main (){
string hi("Hi how are you");
for(int i = 0;i<4;i++)
cout<<hi<<endl;
return 0;
}
When I compiled it and run it, there were no issues, but when I try to debug it, every time the IDE program (Code::Block 16.01) steps in or out of string hi("hi how are you") it gives me a Segmentation Fault.
I know SF is when the program tries to access a space of memory that it is not supposed to access, and I know string class is a C-Sytle string that allocates memory dynamically, and deletes them automatically when the program is finished, hence there should be no issue in memory management, so this code shouldn't be a problem.
BUT in this code I don't understand why do I get a SF when I debug it. When I tried debugging it for the first time and stepped out of hi, there were no errors, but when I tried watching hi, it gave me a SF, and when I try to debug it again, and I steped into string hi I get S.F.
Screenshot of the error FYI
When I was search information about this issue I found entry in Code::Blocks forum, but it is quite old.
However, there is possibility of bug in GDB for MiniGW. If you want to be sure, you should look for this issue and its fix.
I know that this isn't full answer, but you should go to this posts and read they, there is some solution:
Code::Blocks forum's posts:
1. Watching std::string in debugger causes segfault?!?
2. Still having seg fault while watching a string....
I have been trying to trace the source of a segfault in a cython program that I inherited. I have implemented gdb under python3 by executing gdb python3 then run my_file.py and got this:
Program received signal SIGSEGV, Segmentation fault.
__pyx_f_7sklearn_5utils_25graph_shortest_path_leftmost_sibling (__pyx_v_node=<optimised out>)
at /home/my_name/.pyxbld/temp.linux-x86_64-3.4/pyrex/sklearn/utils/graph_shortest_path_strat.c:3195
3195 __pyx_t_1 = (__pyx_v_temp->left_sibling != 0);
Thanks #Veedrac
The call appears as follows:
landmark_points=[random.randint(0,kng.shape[0]) for r in range(self.number_landmark_points)]
self.dist_matrix_=graph_shortest_path_strat(kng,landmark_points,method=self.path_method,directed=False).
Basically instead of calculating the distances between every single point in a graph I want to calculate the distance between all points and a limited number of points defined in an array. where landmark_points is an array of integers kng is a graph of nearest neighbors
kng = kneighbors_graph(self.nbrs_, self.n_neighbors,mode='distance')
the graph_shortest_path is a .pyx code. And I am using version is 0.15.1
#Veedrac thanks for your help. I actually traced the error to the fact that I was using random.randint, when I should have been generating unique random integers with random.sample.
My program only sometimes gets a Segmentation fault: 11 and I can't figure it out for the life of me. I don't know a whole lot in the realm of C++ and pointers, so what kinds of things should I be looking for?
I know it might have to do with some function pointers I'm using.
My question is what kinds of things produce Segmentation faults? I'm desperately lost on this and I have looked through all the code I thought could cause this.
The debugger I'm using is lldb and it shows the error being in this code segment:
void Player::update() {
// if there is a smooth animation waiting, do this one
if (queue_animation != NULL) {
// once current animation is done,
// switch it with the queue animation and make the queue NULL again
if (current_animation->Finished()) {
current_animation = queue_animation;
queue_animation = NULL;
}
}
current_animation->update(); // <-- debug says program halts on this line
game_object::update();
}
current_animation and queue_animation are both pointers of class Animation.
Also to note, within Animation::update() is a function pointer that gets passed to Animation in the constructor.
If you need to see all of the code, it's over here.
EDIT:
I changed the code to use a bool:
void Player::update() {
// if there is a smooth animation waiting, do this one
if (is_queue_animation) {
// once current animation is done,
// switch it with the queue animation and make the queue NULL again
if (current_animation->Finished()) {
current_animation = queue_animation;
is_queue_animation = false;
}
}
current_animation->update();
game_object::update();
}
It didn't help anything because I still sometimes get a Segmentation fault.
EDIT 2:
Modified code to this:
void Player::update() {
// if there is a smooth animation waiting, do this one
if (is_queue_animation) {
std::cout << "queue" << std::endl;
// once current animation is done,
// switch it with the queue animation and make the queue NULL again
if (current_animation->Finished()) {
if (queue_animation != NULL) // make sure this is never NULL
current_animation = queue_animation;
is_queue_animation = false;
}
}
current_animation->update();
game_object::update();
}
Just to see when this function would output without any user input. Every time I got a Segmentation fault this would output twice right before the fault. This is my debug output:
* thread #1: tid = 0x1421bd4, 0x0000000000000000, queue = 'com.apple.main-thread, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
frame #0: 0x0000000000000000
error: memory read failed for 0x0
Some causes of segmentation fault:
You dereference a pointer that is uninitialized or that points to NULL
You dereference a deleted pointer
You write outside the bounds of the scope of allocated memory (e.g. after the last element of an array)
Run valgrind with your software (warning, it really slows things down). Its likely that memory has been overwritten in some way. Valgrind (and other tools) can help track down some of these kinds of issues, but not everything.
If its a large program, this could get very difficult as everything is suspect since anything can corrupt anything in memory. You might try to minimize the code paths run by limiting the program in some way and see if you can make the problem happen. This can help reduce the amount of suspect code.
If you have a previous version of the code that didn't have the problem, see if you can revert back to that and then look to see what changed. If you are using git, it has a way to bisect search into the revision where a failure first occurred.
Warning, this kind of thing is the bane of C/C++ developers, which is one of the reason that languages such as Java are "safer".
You might just start looking through the code and see if you can find things that look suspicious, including possible race conditions. Hopefully this won't take to much time. I don't want to freak you out, but these kinds of bugs can be some of the most difficult to track down.
I have serious problem which is segmentation fault and i am %99.99 sure its because of rewind.
i have somewhat big loop and it runs about 1200 time. in each run of my loop i rewind(fp) in 2 different class method. in visual studio it goes up to 527 times and then when i look at the value of fp, it says unable to read memory. i copy the same code to matrix environment and it goes up to 1027 test.if i stop rewinding i dont get error but my result will be wrong.
now my question:
when each time i rewind, is anyway to delete it from memory at the end of my loop?
for example
FILE* fp;
fp=fopen("filename","r");
for(..;..;..)
{
rewind(fp);
//beginning of my code
.
.
.
//end of my code
is there any command i can use to clear fp from memory right here?
}
any comment makes me grateful
I do some image processing work in C++. For this i use CImg.h library which i feel is good for my work.
Here is small piece of code written by me which just reads an image and displays it.
#include "../CImg.h"
#include "iostream"
using namespace std;
using namespace cimg_library;
int main(int argc,char**argv)
{
CImg<unsigned char> img(argv[1]);
img.display();
return 0;
}
When i give lena.pgm as input this code it displays the image. Where as if i give some other image, for example ddnl.pgm which i present in the same directory i get "Segmentation Fault".
When i ran the code using gdb i get the output as follows:
Program received signal SIGSEGV, Segmentation fault.
0x009823a3 in strlen () from /lib/libc.so.6
Missing separate debuginfos, use: debuginfo-install glibc-2.9-2.i686 libX11-1.1.4-5.fc10.i386 libXau-1.0.4-1.fc10.i386 libXdmcp-1.0.2-6.fc10.i386 libgcc-4.3.2-7.i386 libstdc++-4.3.2-7.i386 libxcb-1.1.91-5.fc10.i386
Can some one please tell me what the problem is? and how to solve it.
Thank you all
Segfault comes when you are trying to access memrory which you are not allowed to access.
So please check that out in the code.
The code itself looks just fine. I can suggest some ways to go ahead with debugging -
Try removing the display() call. Does the problem still occur? (I'd assume it does).
Try finding out where in the CImg code is the strlen() that causes the segmentation fault (by using a debugger). This may give additional hints.
If it is in the PGM file processing, maybe the provided PGM file is invalid in some way, and the library doesn't do error detection - try opening it in some other viewer, and saving it again (as PGM). If the new one works, comparing the two may reveal something.
Once you have more information, more can be said.
EDIT -
Looking at the extra information you provided, and consulting the code itself, it appears that CImg is failing when trying to check what kind of file you are opening.
The relevant line of code is -
if (!cimg::strcmp(ftype,"pnm")) load_pnm(filename);
This is the first time 'ftype' is used, which brings me to the conclusion that it has an invalid value.
'ftype' is being given a value just a few lines above -
const char *const ftype = cimg::file_type(0,filename);
The file_type() function itself tries to guess what file to open based on its header, probably because opening it based on the extension - failed. There is only one sane way for it to return an invalid value, which would later cause strcmp() to fail - when it fails to identify the file as anything it is familiar with, it returns NULL (0, actually).
So, I reiterate my suggestion that you try to verify that this is indeed a valid file. I can't point you at any tools that are capable of opening/saving PGM files, but I'm guessing a simple Google search would help. Try to open the file and re-save it as PGM.
Another "fun to track down" cause of segmentation faults is compilier mismatches between libraries - this is especially prevalent when using C++ libraries.
Things to check are:
Are you compiling with the same compiler as was used to compile the CImg library?
Are you using the same compiler flags?
Were there any defines that were set when compiling the library that you're not setting now?
Each of these has bitten me in subtle ways before.