Programming :: C++: Assignment Operator Copy All The Members Also For Structures Containing STL Objects?
Sep 26, 2010
does the assignment operator copy all the members also for structures containing STL objects strings,vectors,vectors of vectors...)? I did try it on my platform,and it works that way (copying all the fields),but i was wondering if it is a standard behavior or not.
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Feb 9, 2011
I have it so that an Env object contains all the variables in the current scope, and the parent scope. You can also save them to variables like objects, and my idea is to use the "." operator to get values from them.
First, how do I assign to them? I currently have it that only a variable name can be assigned to, but you should be able to assign to an "obj.value" expression, too. How do I keep track of what variable to set and still be able to say it in an expression and have it evaluate to the variable?
Second, these object don't really have a "type", they're just containers that contain any values you want under any name you want. How can I, for example, define a primitive "boolean" object and have things like if statements recognize it?
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Apr 16, 2011
I'm having a bit of an issue using overloaded operators in an already overloaded operator. In my following code, I have overloaded the && operator to compare two Course objects. The operator in turn goes to a function which calls other overloaded operators to compare private object variables of that object to compare them.
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Jul 6, 2011
I got across a peculiar problem with memcpy.History:writing a code which do flash/Read functionality for SPI Parts.
Implementation:
1.memory map the Flash chip registers to userspace. - fine
2.Issue block read command
3.Just print the data I got, using the memory mapped address - fine I got the correct data.
4.Copy the data to a local buffer from memory mapped address using memcpy - FAIL
UPDATE:
on SUSE 11.3 -32 bit the above code worked perfectly, but on SUSE 11.4 - 64bit , Ubantu, Fedora it failed.
I am using gcc compiler obviously. I am using i386/x86_64 OS. Processor: Intel core 2 duo, SNB after step 4 , when I dump the data from local buffer every thing is FF.But step 4, if i implement byte by byte copy using assignment operator, it worked.is there any known bug with memcpy? am I missing anything?
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May 19, 2010
Anyone know some links where i can find about data structures using STL ?
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Jun 17, 2011
I hace some code C/C++ STL, which i need to use for android, using SDK-NDK-JNI.my problem is that i need to pass some STL structures across JNI, I can't pack/unpack data into basic types or arrays of basic types, doing my own simple streaming between the two layers.My application need to pass a pointer to a STL structure which is updated by eachuser interaction wonder if it is possible using NDK-JNI ?Other option is "native activity" but it also needs JNI in some way ... and passing the STL structures wille a requirement, yet.I only can package data into an own streaming if there is a second (concurrent) application running (implementing the STLfunctionality). Is it possible ?
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Apr 18, 2011
I am working on a project that needs to use structures and I'm pretty sure string arrays. First I declare my structures and they must be exactly like this.
typedef struct
{
int hour;
[code]....
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Apr 25, 2011
how to run a linux commands in shell programming using control structures.
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Dec 13, 2010
I am implementing c program to access ext3 file system's metadata. I want to know how to access members of the in-memory superblock structure. I am able access on-disk ext3_super_block structure but dont know how to access in- memory structure and its members.
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May 23, 2010
i'm a bit stuck playing with the following class setup for glut. The actual issue is with the function pointers.Basically the following code is the opengl redbook cube example slightly modified.
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Apr 18, 2011
I'm having a bit of trouble getting the OR operator to work.This is the code that I have:
global.php:
Code:
$vars["admin link"] = "<a href='/path/to/admin.php'>Admin</a>";
$vars["admin ip"] = "xxx.xxx.xxx.xx1";
$vars["admin ip2"] = "xxx.xxx.xxx.xx2";
[Code]...
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May 1, 2010
I have a binary value which I receive from a controller. Say this binary value is 42. Just plain hex 42. If you would look at that byte in a debugger you would see 42.Now this value hold 8 bits each indicating a high or a low output. So 0x42 = 01000010b. Which means bits 1 and 6 are '1'.When I would want to find out which bits are set and which are not in a language like C, I simply do:
Code:
mask = 0x80;
if (binval & mask) {...}
etc..
However I am programming in TCL, and I try to do:
Code:
set mask 0x80
if { [expr ($binval & $mask) > 0] } {...}
etc...
this fails. At the moment the expr is executed, $binval is evaluated and substituted so the expression I am evaluating is
Code:
set mask 0x80
if { [expr ('B' & '0x80') > 0] } {...}
etc...
Eventually I got it working by converting the $binval into a '0x42' string value, like this:
Code:
binary scan $binval c byte
set byte [format "0x%0x" $byte]
set mask 0x80
if { [expr ($byte & $mask) > 0] } {...}
etc...[
Then the expression yields what I want. But this seems so stupid and clumsy. Isn't there a better way where I can compare two binary values without conversions?
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Jul 9, 2011
[Code]....
if the address of stWndClass is 403000h, WHY it would be compile as mov eax,[esi+403004] and the first one would be mov eax,[esi+4]? I know how to get the values 403004h and 4,but do not know why.
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Oct 2, 2010
I have assignment to write bash script and I have to submit it after tommorow . I do not have experience to finish it by myself.I am really need help if any one can contact me. on my email I will be thanks him/ her.
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Jul 13, 2011
I have a simple program from book C++ cookbook, page 291, 8.3, Using Constructors and Destructors to manage resources (or RAII), but it can not get compiled in my g++
------------------------------------------------------------------------------------------------
// Example 8-3. Using constructors and destructors
#include <iostream>
#include <string>
using namespace std;
[code]....
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Feb 8, 2010
I'm very new at Bash scripting and have a bone head issue that I'm trying (and failing) to resolve. I cannot get this one IF statement to work, it seems the comparison operator does not think the resulting number from the $b*$c+$b operation is an integer even though it is a number. Below is a small proof of concept script with the bit I'm having trouble with.
Code:
#! /bin/bash
a=800
b=700
c=.15
if [ "$a" -le "$(echo "($b*$c+$b)"|bc)" ]
[Code]...
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Feb 3, 2011
it's been a long time since I did coding in C, but thought to pick up a very old project again, just to show off what I have been working on ten years ago.I deducted my problem as follows:
Code:
#include <stdio.h>
#include <stdlib.h>
#define bit1 1
#define bit2 2
[Code]...
Why is it saying that bar->act is not a valid lvalue while both bar->act and the bit are cast to (long long)?
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Sep 1, 2014
Is there a way to achieve the following with the square bracket operator?I have a class:
Code: Select allclass A
{
public:
void SetValue(int index, Item* B);
private:
int m_iCount;
ItemCollection Item_Collection;
[code]....
The probelm is that I am not just blindly assigning whatever given on the right hand side to the returned value from operator [], I need to verify it's not NULL, and it is not already there in the Item_Collection, and I also need to increase the count.
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May 10, 2011
I know it is wrong to use the "==" operator to compare the equality of two floating point numbers. Logically it would seem that if the "==" operator is not usable for floating point comparison, then the "<=" operator would also not be usable. Is this true? The lack of google search results on this topic made me think that it must be true. If that is true, then is it true that the only way to compare floats with <= or >= is with something like the code below? Code: bool smaller_than_or_equal(float a, float b) {
if ( fabs(a-b) < EPSILON){return true;}
else if (a < b) {return true;}
else {return false;}
} I think this is a general question, but if specifics are necessary, I am using the C++ language to code at the moment.
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Jan 4, 2010
I am trying to learn C++.I implemented a simple archive program, and I am in a situation in which the user is prompted by a menu to make a choice.So I have some cout instruction to illustrate the possible choices and then
int choice;
cin>>choice;
and everything works fine.I introduced this code in a "while" loop that checks wether the choice made by the user is valid or not:
bool check=true;
int choice;
while(check)
{
cin>>choice;
if(the choice is valid) {...;check=false}
else cout<<"please make an other choice"
}
What is happening is that if by mistake the user introduces a character in place of a number, the loop repeats indefinitely because the program, when it get to the "cin" instruction, does not pauses to wait for a new input.
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Apr 25, 2010
Can one of you point me towards a comprehensive print function tutorial in perl? I was under the impression that everything within quotes will get interpolated - but I am running into exceptions where it is not desirable to run some varaibles under quotes.
ordinal.pl
1 #!/usr/bin/perl
2 $idx = 1;
3 foreach $letter (a..z) {
4 print "Letter #",$idx++," is: $letter
";
5 #print "Letter # $idx++ is: $letter
[Code]...
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Jun 12, 2010
I've been reading and googling, etc. I've seen some things, but not a definite explanation of this. What is the appropriate way to mimic a C ternary operator using Python? Isn't there an exact proper way to do it? Any difference for using lambda functions? I'm sorry, but I've been searching and it's ambiguous to me how this should be handled. I would appreciate a person's help on this. I came up with this link, but I'm wondering if I'm missing something.[URL]...
So, is that it? In Dive Into Python, it's using the and-or trick. Well, if the above post is the full explanation,
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Jun 27, 2010
how to overload the subscript operator ([]) for a list class?
Code:
template <typename T>
class list
{
public:
struct node
[Code]...
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Mar 27, 2010
I have tryed out this operator on program:
Code:
#include <iostream.h>
#include <iomanip.h>
#include <fstream.h>
ofstream myfile;
[code]...
which definitly is not the same number. I guess somewhere in the convertion from double to char* ("<<") something is not right and what can i do to save these double numbers in an accurate manner in a file?
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Nov 23, 2010
I would like to compare the nmlookup result of IP's stored in the file ips with a list of PC names stored in the file pcs.
Code:
for line in `cat "ips"`
do
[code]....
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Oct 28, 2010
I have a question about shared objects and when mapping and linking is established in the following code...Well more of a verification.
getsetx.c - shared object source code Code: unsigned long x = 0;
unsigned long getx(void)
{
return x;
}
[Code].....
Now its my understanding when I execute ./testit, getsetx.so will get mapped into its address space at start up and testit will link any functions as they are needed..
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Apr 6, 2011
I have two classes, for argument's sake A and B. A implements the core functionality, B is an encapsulated data structure. If you imagine this situation
[code]...
From within B's member functions, I would like to access the public function() in class A. This is not an inheritance issue, they are two discrete classes with radically different functionality. Class A makes an object of B.
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Aug 31, 2010
I am trying to make a hash of objects in perl (long story.) I have a package containing the main hash and all the subroutines necessary to work with it. My "new" subroutine used to add an object to the hash goes like this:
Code:
$tmpdir="/tmp";
$subdir="/AutoScript";
[code]...
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Jun 24, 2010
I cannot get this to work
Code:
#!/usr/bin/python
# -*- coding: iso-8859-1 -*-
import re
# @description "This is a describing text about the file currently documentet";
#DocC documentation prototype
[Code]...
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Aug 30, 2010
The goal is to auto-update a webpage that contains links to network devices. These devices are all set to DHCP, and their hostnames are not guaranteed to stay the same, so static IPs or accessing via hostname is NOT an option.
Process: Run a script every hour or so to query devices on the local network to generate a list of responding devices by MAC address and what their current IP is (results.lst). Using a "static" MAC address list file "printers.db" as the database search "results.lst" to find specific MAC addresses. When a match is found, grab the IP from "results.lst" and update "index.html" with the new IP address. No comparison needs to be done between "results.lst" IP and "index.html" IP as I just want to overwrite whatever is there.
Here is what I have so far (using dummy data): PRINTERS.DBProduct Mac Address Printer1 00:00:00:00:00:11 Printer2 00:00:00:00:11:11 Printer3 00:00:00:11:11:11 Printer4 00:00:11:11:11:11 Printer5 00:11:11:11:11:11 Printer6 11:11:11:11:11:11 TEST.SH
Code:
#!/bin/sh
#------------------------------
# Quick Links Updater v2.0 |
# By Rob M. |
# with help from Tim F. |
#------------------------------
[code]....
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