i am wondering why the following simple code causes a segfault on exit,when the std::string destructor is called.
Quote:
#include <iostream>
#include <string>
using namespace std;
[code].....
I guess the memset messes with some internal std::string's data structures/pointers. I personally am anti-memset,and always avoid them.
The below program is giving unpredictable and wrong output when I compile with g++ under Ubuntu OS , tried with the complier avilable with Ubuntu 8.04 and Ubuntu 10.04 LTS.
But it works fine when complied and ran Redhat g++ 3.4.6
I am fairly new to linux still and I'm currently trying to write a shell script (which I have never done) that is supposed to run the xrestop(like top) program. What I want to do is execute the program and check the identifier column to see if a certain program is running. If it is running I want to strip the data from that row of the terminal say every 5 seconds or so and put it in a text file. Is this going to be a complicated thing?
Heres a list of the columns when you run xrestop program res-base Wins GCs Fnts Pxms Misc PxmMem Other Total PID Identifier.
copy string a to string b and change string b with toupper() and count the chars
View 3 Replies View RelatedI noticed that if I have "exit" in a bash script file., e.g. script.sh,that when the word "exit" is reached, and the script file being executed is not in the PATH nvironment, i.e. ". script.sh", the whole konsole shell profile is exited! What gives here? Is there another command compatible to "exit" to prevent this, or will I just have the leave the "." part in the PATH enviroment, which is, to my understanding, is not recommended? I desire for a "goto" function in bash script files
View 11 Replies View RelatedIn linux, creating thread is same as process (clone()), except the virtual address space gets shared with the parent.If a running main process(thread) creates new thread, and if main thread exits, why should the new thread too exit? both are different entities, The same doesn't happen if the child thread exits, the parent thread would be alive.
View 1 Replies View RelatedWe have an application which allows user to perform Drag and Drop operations. The problem we are facing now is the application crash. System works fine for some time and allows user to perform many drag drops successfully. But after running for some time and user perform a drag and drop the system crashes.Following stack trace we are getting while system crashes.
XtDispatchEvent [Event.c]
RemoveAllPMgr [libXm.so.3]
XtCallCallbackList [Callback.c]
[code]....
I feel there's a bit of a misunderstanding going on between C++ and me...My problem is that I have a deque of pointers to a class, and create objects then add them to the deque in a for loop. However, the destructor is called on the object as soon as the loop quits.
Code:
This prints:
Code:
Now, if I change the deque from deque<Test*> to deque<Test> then it works fine - I get:
Code:
However, I can't do this with my actual code, because I am creating a deque of pointers to an abstract class, so it won't let me instantiate the class. (This is all so that I can take advantage of polymorphism, and call functions on a set of similar objects without worrying what type of object I'm dealing with).
So, I suppose my question is: what is the correct way to create that deque of pointers to the abstract class? I don't seem to be barking up the right tree currently.
I've been trying to understand pthread in C a little better. So I made a simple program that takes in a string from the command line and creates a thread to print the string. I've looked online and copied the basic concepts but there are something things I'm confused about. The programs works just fine, but I have questions. Here's what I have so far.
[Code]....
One thing I'd like to know is why the 3rd argument in the pthread_create function which is my SendMessage function needs to be typecasted to a void pointer and then send the address of the function. Also as for the 4th argument, I would see typecasting to void pointer in some of the pthread examples I saw online, but in my case I'm passing a char pointer, would this be correct? In which case would I ever want to pass a void pointer?
Do I need a pthread_exit(NULL) in my main and in the SendMessage function? If so, why? I added the sleep() function so that I could let the pthread_exit function in my SendMessage function execute first. I simply saw that the online examples on pthread had pthread_exit() in both locations.
I have a set of lines as ahown below:
Leon went to school
Leon came back from school..
Leon had dinner...
I have to replace the line containing "dinner" by a single string LUNCH...
I need to creates string suffixes out of a Reference string. for eg. suffixes of abcdefg will be
1)bcdefg
2)cdefg
3)defg
and so on...
create an array of pointers to point to the first few characters and then use that pointer to print the rest of the string.But when i print using the pointer i get GARBAGE values! shudn't std::cout<<ptr[w] print the string following the char it is pointing to? why do i get garbage values?
So if I'm given a location of a file like:
How can I just take the type of the file at the end? I know I can use strrchr() for a period to get the pointer to the period just before file type. Is there a build in string function that will just take the rest of the string from a certain point on forward in the string? I know it wouldn't be much work to make it myself, but I figured I would find out if it already existed before doing it.
Code:
The error is:
Code:
What I want to do is take input of ip4 as a string, convert it to an integer to add 1 to it, then reconvert it back to a string. Its not working.
My full code is:
Code:
I've been given a custom-made string class which handles string, wstring and bstr. It has a number of methods and assignment operators to convert to and from different types. The app I work on compiles happily in VS6 and VS2008, but when trying to compile in Redhat (version 4.1.1 in Redhat 5.0)
[code]....
I have the following two type of strings1: A/D2: A/C/DI am trying to write a subroutine to check whether all of the letters in string 1 appears in string 2. If yes, return true. If not, return false. In the above example, all the letters (A and D) in string 1 are also present in string 2, so I return true.
View 4 Replies View RelatedI want to generate core dump files from my program when it crashes. Its a pretty big process and has about 10-11 threads in it.I have followed the documentation to enable core dump by setting ulimit to unlimited etc. I quickly tried "A demo program creating a core dump" from the following webpage, which succeeds in Segfault and dumping a core file in the directory that I configured.However, I tried running my original program and caused it to crash. I did this by making calls to kill(), raise() or the same null pointer access as shown in the webpage above. In each case, my program crashed but did not generate a core dump file. Am I missing something?My program is in C++ and my environment is Redhat 9.0 (kernel 2.4.20)
Going through the "Why do I NOT get a core dump?" section on the same webpage as above, I can see two potential problems. One - there are issues with the suid/sgid (bullet # 6). I am not able to change any settings with suid because my system does not contain either /proc/sys/fs/suid_dumpable or /proc/sys/kernel/suid_dumpableTwo, my program has threads in it and the bullet # 8 is the problem.
Do I have the convert the int to a string using stringstream then convert the string to a char? or is there a more direct way?Also is there a way to tell the length of a int?
View 5 Replies View RelatedI have one xml string as follows.
I have to parse it and have to get the elements On AC, NO system battery, NA, NA and hav to staore in a buffer. I want a c program to do this. can i use DOM or COM in unix
What are the uses of return 0, return 1 and exit statements in C
View 4 Replies View RelatedI don't know if this is the best place to ask this question. This question arose when I had a g++ compilation error: error: expected constructor, destructor, or type conversion before '.' token The above message can be correctly displayed in urxvt or xterm. But in mrxvt the '.' part can't be displayed correctly. Then I noticed that the quote signs are actually different from the usual ones and there seems no way to type ' ' from the keyboard. What are the differences and how to make mrxvt to display ' ' correctly. I found mrxvt very good and easy to configure.
View 4 Replies View RelatedI am running a command pretty similar to the one below:
Code:
I need to capture the exit status of that part of the command.
What I am trying to do is set a variable that can be modified within my_job.sh, and used to exit.
However, no matter what I set "status" to in my_job.sh, it exits with "0".
What can I do differently?
How exactly can I use the exit status of a command in an if statement ?
Something like this:
Code:
I am using a program that reads in data from a serial port and then sends that data out over a TCP connection. The problem I'm having is that the only way I know to exit the program is to do a 'kill PID', but doing this means the program doesn't go through the motions of closing the TCP connection properly so I have to wait some random period of time for the port to free itself or else when I try to start it back up it tells me that it can't bind to the specified port.The general structure of the program is as follows
Code:
int main(){
// initialize some stuff
[code]...
I am trying to write a python script which logs into a NetApp filer and fetches some data. I am using the telnetlib library. Filer does not take exit command. So it expects Control-D. How to send that via python script?
View 5 Replies View RelatedI have this command in ksh:
1. typeset -i INTEGER INTEGER=aaa In all platforms except of Linux it is failing and return exit code 1 Why in Linux it is not failing? I must it for my number tests
2. The same for printf command. Only in Linux the bellow command is not failing: printf "%d" aaa
I'm new to scripting and I have a trouble with if statement syntax. The code is: Code: #there is a diff command here, and it does what i want but#i wanna see 1 if the exit value of diff is 0, and otherwise i wanna see 0.#the problem is here: (syntax error near unexpected token "then")
if["$?"==0];
then
echo 1
[code].....
Is there a way to count the number of errors- an exit variable $? from one function?
The output from the exit variable (either erroneous or correct (1) or (0)) is it possible to add the erroneous one ups?
How do i run a part of code on exit in a shell script?Suppose i have four echo statements like the following:
echo "Stmt 1"
echo "Stmt 2"
....some code goes here...
[code]...
Consider the following code:
Code:
...
int ret=0;
[code]...
I have a problem with the last point of some homework I have for an OS class. I need the program to print the pid upon execution, then for 10 seconds react to SIGUSR1, SIGUSR2 and SIGTERM. If either USR1 or USR2 is received, the 10 seconds are reset. Some of the functions I'm told to use are alarm(), pause() and signal(). The nicest way I found was to handle SIGUSR1, SIGUSR2 and SIGALRM in the parent process, with SIGALRM killing the child (with a SIGTERM). In the child a pause() (or for(; pause() would be enough for it to be alive until killed from the SIGALRM handler in the parent.
What I found is that I can't just do a wait() in the parent process, waiting for the child to be killed, since whenever the parent receives a SIGUSR1 or SIGUSR2, the right handler is called but the child exits nicely. I tried blocking/ignoring those signals in the child, since the default behaviour for SIGUSR1 and SIGUSR2 is to terminate the process, but the result is the same. The only way I could do it is using a waitpid() within a do { } while(!WIFSIGNALED(status)) since when the child gets killed with the parent's kill(), it's WIFSIGNALED, whereas when it exits after the parent handles a SIGUSR1/2, it's WIFEXITED.
P.S. What I'm doing to achieve the expected 10s window is calling alarm(10) in the parent process and again within the SIGUSR1/2 handlers. In the SIGALRM handler I kill the child and within the child I simply do a for(; pause()