Programming :: Pass By Reference A Parameter Without Assigning A New Object?
Dec 28, 2010
How can I pass by reference, a parameter, without assigning a new object? In my first example, var = "changed" creates a new local object. In the second, mylist.append will affect the reference target. How to i achieve the same effect with example 1?
Code:
#!/bin/python
var = "unchanged"
def print_string( var ):
[Code].....
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Jan 21, 2011
Say, i have an imaginary std library function, which I want to call.
Code:
void std_lib_func(ObjectType *param);
Now in my c++ program, I have a main() function, and I will like to call a customized function (which will in turn call the std lib function) from the main function, as below:
Code:
int main()
{
ObjectType *aobj;
customized_func(aobj);
}
[Code]...
I tried the below but get an error that the std lib function is expecting a ObjectType* param, not aobj. How should I work this out.
Code:
void customized_func(ObjectType aobj)
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Sep 2, 2010
Kindly take a look at the code below :
Code:
#include <stdio.h>
struct test
{
int i;
int j;
[Code]....
why i am getting this error. I know the error is occuring because i have assigned values to obj.i and obj.j outside main(). But i want to know why do that result in an error. From my part i have created an object 'obj' of stucture 'test' and assigned values to its variables.
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Mar 6, 2010
I've been using the PPA version of banshee, and I got this error - just wondering if anyone else has it too! I'm able to play a song, but when the song finishes and the next one starts I get this error: Banshee Encountered a Fatal Error Object reference not sent to an instance of an object Error details:
Code:
An unhandled exception was thrown: Object reference not set to an instance of an object
at Hyena.Gui.Theming.GtkTheme.GetCairoTextMidColor (Gtk.Widget) <0x00017>
at Banshee.NotificationArea.NotificationAreaService.get_TextLightColor () <0x0002f>
at Banshee.NotificationArea.NotificationAreaService.MarkupFormat (string,string[]) <0x00043>
at Banshee.NotificationArea.NotificationAreaService.GetByFrom (string,string,string,string) <0x000d7>
[Code]....
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Mar 9, 2009
I have created a simple test class - Mortgage, with the class declaration in the .h file and the class's methods defined in the .cpp file. (mortgage.h && mortgage.cpp, respectively) Straight up C++ 101 as far as I can tell. I instantiate the class in the main() function, which is defined in practice.cpp. Using Geany on Ubuntu, both the practice.o and mortgage.o files are created, but then I get a linker error: undefined reference to class::functionName
I get it for each function. If the mortgage.cpp file is foremost in the editor when I click "build", then I get the undefined reference to main() error, if practice.cpp is foremost (where the main() function is) then I get undefined reference to Mortgage::Mortgage(), and all the rest of the functions defined for that class. How do I get the linker to know where my object files are so it will link them in? Or is the problem somewhere else entirely?
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Oct 4, 2010
I have the following code in the TCP server:Quote:
while (my $from_who = accept(CLIENT_SOCK, TCP_SOCK)) {
my $data = '';
#my $previous = select CLIENT_SOCK;
[code]...
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Apr 13, 2011
I am creating two shared libs that i intend to be dynamically linkable in C and C++, cross platform Linux/Windows/Mac. As a basic sketch, true for both libs, the lib code is in several .c/.cpp and .h files. For now, I'll talk about the part that I am actively working on, a lib named Discover, i.e. libdiscover.so.1.0. First, everything is in a namespace, RemKon_Discover.
The main Discover.cpp defines the methods for the Discover class (declared in Discover.h) and has extern "C' routines that can return pointers to my main c++ object. The call to GetLibraryMainPointer() creates a Discover class object, theMainObject (ok, I win a prize for dumb names) and returns the (non-mangled) pointer to the caller over in my test program. The Discover class itself is declared extern "c" and the tester program #includes "Discover.h".
In the test program, dlopen() correctly opens the lib and dlsym() gets the pointer to theMainObject. However, when I use that pointer in the tester program to access a method (aDiscoverObject->hello(), e.g.) I get compile time errors saying that Discover::hello() in an undefined reference. My makefile is attached.
[Code]....
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Mar 10, 2010
I have a backup schedule running a full backup everyday. I'm using webmin to manage these backup now. The problem is when the dump command sends a prompt asking if we want to rewrite the tape, Webmin does not display this prompt and we end up having to terminate the backup -> erase the tape(which takes a long time) and then run the backup again.I was wondering if there is a technique that could be used to pass "Yes" as a parameter to the dump command, much like in windows? or if there is a more efficient way of getting this done.
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Nov 4, 2010
I have an issue that is fixed by changing the lpfc driver to run using MSI interrupts. This is done by adding "options lpfc lpfc_use_msi=2" /etc/modprobe.conf.local file.
Is there a way to make this change using kernel boot parameters?
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Mar 1, 2010
Only ones I can think of seem overly complex, and I'm sure there is a simple solution I am overlooking. I have a class, it has a member who is an object. This object needs to be able to represent an object of different types.
[code]...
Where "surface" could be several different types, which will be set during execution. Hope this is clear enough. I have tried using templates but am getting "data member cannot be a member template". Either I have incorrect syntax, or am not implementing it right. another solution would have one class containing definitions of all possible shapes, But this would take up extra memory. Other solutions I thought of seem too round-about, and seems there is a simpler solution that I have overlooked.
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Nov 5, 2010
I am trying to run this and was into issues
function() {
node=echo "10.11.12.13" | awk '{split ($0, a, "."); print a[1]}'
}
[code]....
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May 4, 2010
Using things like awk/sed, but have managed to cobble together what I needed so far without a problem. The only thing I'm struggling with is to assign the content of a particular line as a variable, and then to use it again throughout the file.
For example, if what I want is the first line of the file to become the variable "from1", and then to replace the word "Subject" in the file with the string "Message from [from1]". What I thought would work
I tried a few diff combinations but nothing seems to work. All I get is the terminal hanging indefinitely.
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Jul 25, 2011
I am assigning a file path to a variable like
$1 means it should accept some file name from cmd prompt but in my case its not working.
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May 4, 2010
I got the following modprobe scripts modprobe -k -q streams what does the -k parameter mean?. is it exist in older modprobe? I don't see -k parameter in recent modprobe.
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Mar 1, 2011
I am having all sorts of trouble trying to assign a variable within an awk script with the system command. I know there is a lot of ways around this problem, but for efficiency reasons, I would like to, within my awk script, do something like
system(x=3)
or
system(x=NR)
and, latter on the shell script which calls the awk script, use the variable $x. But nothing is passed to x. I have already tried things like
command = "x=3"
system(command)
and also used a pipeline within the system to pipe it to /bin/sh In fact tried a lot of stuff like that, using $(( )) etc etc etc I can create directories e write to files (yes, i could write to a file and read from there, but I dont think it is efficient, plus I am puzzled).
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Nov 25, 2010
I am trying to execute a Unix Command in perl and assigning its output to an array:
Code:
@File_List=exec("ls -1 /tmp");
but it is not working. I have tried the perl function system() also but its return code is
[code]...
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Oct 2, 2010
I am working on some minor programming projects. and wouldt like to keep track of them by version numbers. E.g. 1.0.0
Is there a tool or other method for automatically assigning version numbers to software ?
I am currently using Mercurial. as far as i can see it only assigns revision numbers. E.g. 5
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Mar 7, 2010
Groovy is an object-oriented programming language for the Java platform. I do not have experience in Java, only perl and shell scripts. Recently I have been asked to maintain a software written in groovy (also to make enhancements). So can I learn groovy without knowing java language. or isit I have to learn java before venturing into groovy.
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Jun 11, 2010
If I have the following links in HTML
Code:
<a href=lang.php?lang=cymraeg>Cymraeg</a>
<a href=lang.php?lang=english>English</a>
and lang.php has a link to page2.html, how do I pass on the value of the lang parameter from lang.php to page2.html? The value needed is the one passed in to lang.php.
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Jul 9, 2010
I have a small board that has a static ram board attached to it. I have two different programs that each write to a byte of memory in the static ram board. I get a file descriptor to the device memory with the following code:
int phymemfd;
phymemfd=open("dev/mem, O_RDWR | O_SYNC);
This opens the physical memory for both reading and writing. Next I get a pointer to the beginning of my ram board.
volatile unsigned char *novram;
novram = (unsigned char *) mmap(0, getpagesize() * 31,
PROT_READ|PROT_WRITE, MAP_SHARED, phymemfd, 0x11AA0000);
I do this same code in two processes that are both running and this works fine. Now, if I take out the O_SYNC parameter, one of the programs gets into some sort of weird state.My understanding of the O_SYNC parameter is that it cause the process accessing the memory location to block, not allow another process to run, until the first process has finished writing to it.I can see that if my program doesn't block, I wouldn't really know what was in the memory location, but would I can't see how it would cause any other type of system problem.
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Jun 23, 2010
I am facing the problem of calling cfitsio library from C program in linux. when i am givingthe option "gcc -o CreateLevel1DataFitsFile CreateLevel1DataFitsFile.c -lm -lcfitsio
"i am getting following error
/usr/lib/../lib/gcc/i386-redhat-linux/3.4.4/../../../libcfitsio.a(getcolj.o)(.text+0x7065):/backup/Astrosat/learning/cfits/cfitsio/getcolj.c:3098: more undefined references to `__xtoll' follow
[code]...
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Apr 26, 2010
Below I've presented the declaration, definition and the calling method of a function w.r.t pass by reference:
Declaration
Code:
void getUnpackedMsg (unsigned char &data, unsigned int numberOfBits);
Definition
line 278: Shown in RED
Code:
void packedMessage :: getUnpackedMsg (unsigned char &emptyArray, unsigned int numberOfBits)
{
...
...
printf ("
[code].....
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Mar 19, 2010
I was trying to make a code for passing variables by reference..here's the code:
#include<iostream>
using namespace std;
void fun(int& ,int& );
int main(){
[Code].....
invalid initialization of non-const reference of type 'int&' from a temporary of type 'int*'
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Jul 20, 2011
I wrote a small test program, and this is what happens when I try to compile it:
Code:
$ g++ -llua main.cpp
/tmp/ccHJ8HR3.o: In function `main':
[code]...
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Dec 10, 2010
Code:
#include <string.h>
int main ()
{
stricmp ("anisha", "kaul");
return 0;
}
Code:
[code]....
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Apr 5, 2011
When I compile my code in Linux (ATCA machine), I am getting the following error: /vobs/ims_do/lib/rhlinux/debug/libnem-dummy_td2.so: undefined reference to `__isoc99_sscanf'
The same code is being compiled in Solaris without any problems.
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Jun 21, 2011
I'm using Linux and I have the following files:
The function F1() is declared in fileB.h and defined in fileB.cpp. I need to use the function in fileA.c, and so I declared the function as
However, during compilation, I got the error fileA.c: (.text+0x2b7): undefined reference to `F1'
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Jun 22, 2010
When I try to compile my code using g95 or gfortran:
Code:
subroutine dipole_tilt(glong, glat, utsec, tau, day, hgraze)
implicit none
[code]....
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Dec 4, 2010
i want to pass variable in mysql qyery in c programming
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Apr 8, 2010
bash script:
Code:
$ bash --version
bash --version
GNU bash, version 3.1.17(2)-release (i486-slackware-linux-gnu)
Copyright (C) 2005 Free Software Foundation, Inc.
Code:
[serv:]$ cat test.sh
#!/bin/bash
[Code]...
The question is, how to config it works through 'function cool {}' or cool() {} with position parameter
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