Is there some way to generate an initializer list algoritmically?
In the case I'm thinking of, I want to initialize a map<> to pair<key, constant> over all expected values of key.
Obviously i could write a loop to initialize after construction, but it would be nice if it could be done in one statement.
#include <iostream>
#include <initializer_list>
using namespace std;
void doSomething(std::initializer_list<int> list) {
} int main() {
doSomething({2,3,6,8});
return 0;
}
I write a small piece of code like above. But I can not compile it successfully. I try it both with and without the line "using namespace std", but nothing worked.
The error list: Symbol 'initializer_list' could not be resolved
I use Eclipse CDT and GCC 4.9.1.
In order to test catching exceptions from an initializer list, I deliberately did bad practice by hard coding an argument to a ctor that would cause a std::bad_allocto be thrown. Obviously better practice is to send a variable, but that would cause a compile error, so I hard coded a value.
The program I wrote creates Prime Numbers up to a specified limit which is an argument to the ctor of type std::size_t. The program works fine IMO, using g++ in cygwin:
$ time ./PrimesExe
Limit is 2000000
148933 Primes Created
real 0m1.210s
user 0m1.123s
sys 0m0.046s
Now when I send something invalid like a negative number or something too big for std::size_t, the program seems to run indefinitely, when compiled with g++ under cygwin. I haven't tested it yet on Linux.
However, if I do the same on VS2013 express, it takes about 15 seconds to print the expected caught exception message. I was not expecting it to take so ridiculously long compared to the reasonable amount of work involved in doing primes up to 2 million.
I have read up about what is involved in catching exceptions: stack unwinding, keeping track of what needs to be destroyed etc. But this is 1 object with 1 ctor argument, no Base classes or any other complications. So why such a long or indefinite amount of time?
This whole example is probably contrived, and I am wondering whether exceptions is the right tool for this - it is similar to the divide by zero problem, or could be considered a programming error to call a ctor with a bad argument?
Also, catching an exception thrown by an initalizer list seems a bit awkward in that one seems to have enclose the creation of the object and all subsequent uses of it (and any code in between ) in the same try block, otherwise it goes out scope. I suppose I could try to write a wrapper function that returns a smart pointer reference to a valid object, but I would have to test the validity of it's return too. That's the awkward part - there is probably a better way?
Are there any recommended ways of recovering from initializer list exception, that is, to allow the user to enter a new hopefully valid value and try to create the object again?
I have a project that compiles fine with VS 2010. As I compile it with VS 2012 it generates the entitled error. Why?
View 5 Replies View RelatedThe below code is taken from the open source 7zip project (7z920CPP7zipUIFileManagerBrowseDialog.h)
Code:
class CBrowseDialog: public NWindows::NControl::CModalDialog {
What does the single colon (CBrowseDialog:) mean? Is that Initializer List?
I know the double colon (NWindows::NControl::CModalDialog) is Scope Resolution Operator.
Why is (: public NWindows::NControl::CModalDialog) used with the class declaration?
Similar code is found through out the project along with class declarations.
Suppose you have a switch statement defined like:
switch (parameter) {
case ONE:
case TWO:
// ... other n-2 cases
case N:
doSomething();
break;
default:
somethingElse();
break;
}
What is the complexity of the doSomething()? Is it still equal to the complexity of doSomething() , or the complexity of doSomething() plus the number of case statements? In other words, does the number of case statements a conditional piece of code has count towards the complexity?
#include <iostream>
int ival1
int ival2=1
int summe
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int main() {
[Code] .....
If I compile it I've got these errors
[Error] expected initializer before 'int'
recipe for target 'rechnen.o' failed
I'm working on a school project learning C++. I'm running into an error I can't seem to find the answer for (see topic title).
main.cpp
#include <iostream>
#include <string>
#include "Signature.h"
#include "Genome.h"
using namespace std;
// Calling Function
int main() {
Signature Sig1; // Create Signature object
Genome gString1; // Create Genome object
[code]....
Im trying to output an array to a bmp file but i keep getting and error that says excess elements in scalar initializer.
i have tried both of these codes and still get the same error.
float pond[n][n];
int outputBMP("finaldata.bmp", (float*)pond, 499, 499);
float pond[n][n];
val=&pond[n][n];
int outputBMP("finaldata.bmp", (float*)val, 499, 499);
I working on an assignment that processes an array of structs. In the main function I am attempting to declare an array of Author structures with 3 elements. It is supposed to be initialized to set all of the string fields (the names and book titles) to "NONE", and the double fields (the prices) to zero. This is supposed to be done in one statement, not using loops. Here is what I have.
struct BookInfo struct Author
{ {
string title; string authorName;
double price; BookInfo books[SIZE] //SIZE = 3
}; };
//prototype for function to print the content of array on screen
void showInfo(Author a[], int size);
[Code] .....
I was under the impression that an array can only hold the values of one data type. So doubles and strings in the same array doesn't make sense to me. However, that's the example my teacher drew up. The error keeps telling me that there are too many initializer values.
I just got this warning from codeblocks:
Code: extended initializer lists only available with -std=c++11 or -std=gnu++11 that I belive is due to having initialized a class array in the constructor somewhat like this:
Code: class xpto {
public;
xpto():num{25,25}{}
int num[2];
};
Since the code I'm developing is not meant to be compiled only by me and I want to ensure there are no incompatibilities with other machines I would like to kow whats the best way to initialize the array that is not c++11 dependent.
Is there no way to do it directly on the constructor "pre-instructions" (don't know the correct designation for the initialization section)? or do I have to put the instructions on the constructor body.
I wrote a template class for Matrix manipulation. The compiler cannot compile the source and complains
Matrix.h:144:41: error: expected initializer before ‘const’
What is the problem of the code enclosed below?
#ifndef MATRIX_H
#define MATRIX_H
/**
* @file Matrix.h
*The Matrix template class written for simplify the matrix manipulation.
*/
#include <cassert>
using namespace std;
template<typename T>
class Matrix {
int rows,cols;
[Code] .....
So I have this class
class DataBase
{
// Change the connection path here to your own version of the database
public SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;AttachDbFilename=|DataDirectory|UberDatabase.mdf;Integrated Security=True;");
public DataBase()
{
}
}
And in the same namespace as this class I have a form that calls it like so:
DataBase dBase = new DataBase();
SqlCommand trythis = new SqlCommand("Register", dBase.con);
However, I'm getting the field initializer error on dBase.con. I'm not sure why, but when I call the database from another file (program.cs) it works fine this way.
From HP / Microsoft (Visual Studio C++) <list>:
Code:
struct _Node
{ // list node
_Genptr _Next; // successor node, or first element if head
_Genptr _Prev; // predecessor node, or last element if head
_Ty _Myval; // the stored value, unused if head
};
The stored value is wasted space for the list head. Is there any advantage to implementing list using the same structure for a list head and node?
Code:
// Write a function called insertEntry() to insert a new entry into a linked list.
Have the procedure take as arguments a pointer to the list entry to be inserted (of type struct entry as defined in this chapter), and a pointer to an element in the list after which the new entry is to be inserted.
// The function dveloped in exercise 2 only inserts an element after an existing element in the list, thereby prenting you from inserting a new entry at the front of the list.
(Hint: Think about setting up a special structure to point to the beginning of the list.)
#include <stdio.h
struct entry1 {
int value;
struct entry1 *next;
};
[code]...
This is a working version of the exercise, but I don't think I'm doing what's asked. I was able to add an element to the beginning of the list using an if statement, not creating a special structure that points to the beginning of the list. How would I go about creating a special structure that points to the beginning of the list to add a new element at the beginning of the list?
I'm trying to display a list of MSMQ messages in a list box based on a drop-down list holding the environment.So i've setup the binding and i know that the list loads but nothing shows up in the list? I should be setting like a display member or something but i'm not entirely sure
const String msmqAccelaDev = "FormatName:DIRECT=OS:tcc-intsrvTCCIntegration.MSMQ.Service.Dev/TCCMessagingService.svc";
const String msmqAccelaProd = "FormatName:DIRECT=OS:tcc-intsrvTCCMSMQFail";
const String msmqAccelaTest = "FormatName:DIRECT=OS:tcc-intsrvTCCIntegration.MSMQ.Service.Test/TCCMessagingService.svc";
String currentQueue = "";
private void environmentChange()
[Code]...
I'm working on a linked list and was wondering how this looks to everybody else for a deleteList function.
void deleteList(Node* head)
{
Node* iterator = head;
while (iterator != 0)
[code].....
I have a linked list comprised of chars like so...
Code:
node1 - "p"
node2 - "o"
node3 - "p"
I need a function that will take in three perameters...node *replaceChar(node *head, char key, char *str)Stipulations of this function. head is the head of the list, 'key' and 'str' are guaranteed to contain alphanumeric characters only (A-Z, a-z, and 0-9). str can range from 1 to 1023 characters (inclusively). So if I call this function with these perameters..
Code:
node *head == /*the head of the list to be examined*/
char key == "p"char *str == "dog"The new list will look like this...
node1 - 'd'
node2 - 'o'
node3 - 'g'
node4 - 'o'
node5 - 'd'
node6 - 'o'
node7 - 'g'
All instances of 'p' were replaced with 'dog' I have a toString function which takes in a string and converts it to a linked list and returns the head. So assume that you can call the function on str = "dog" so...
Code:
toString(str) == /*this will return the head to the list made from the str*/
If it's unclear what my question is...I am stumped on how to write the replaceChar function the one that takes in three perameters..
I want to maintain a list. which will update at regular interval. so I thought to with linked list. Earlier I have used linked list.
Code:
typedef struct
{
short nwkaddr;
unsigned char macaddress[8];
}device_t;
}
[code]....
This program is giving many errors. I tried lot to fix it. If I fix one then other bug is arising. for that I did't mentioned what bug i got.Main Issue is while (curr->next->list != NULL) this is giving segmentation fault if i add element second time
#include <iostream>
using std::cout;
using std::cin;
using std::endl;
using std::ios;
#include "Course.h"
#include <list>
[Code] ....
The program works well, except for the fact when it prints out the list (starting at the for-loop on line 65) each line is the same as the last, like it overwrites itself every time it traverses the while(true) loop.
I would like to add a new function to my class, "reverse" that would reverse the order of the list. I have added a prototype in the "public:" section of the code (see the comment with PROTOTYPE in it). Your task is to complete the implementation (see the comment with IMPLEMENTATION in it. See the main() function to see how the results should look
#include
#include
using namespace std;
class List {
public:
// Constructs an empty list
List();
[Code]....
I cant seem to get the right function to put into reverse I have tried everything Im not sure where to start!
I have a concurent queue holding lists, where I have one reading thread and several writing workers. My writers are adding to those lists. Now I just lock the list before I add to it -
if (transaction_calls.TryGetValue(strike, out tranlist)) {
lock (tranlist) {
tranlist.Add(tran);
}
}
Is this enough?
What my reader is about to do, is to see the list size, and reads all the data from list[i] till list[last] - I don't really care for getting the true last, meaning that if while reading list.count, another elment was added, I don't mind ignoring it.
I presume I can't use the foreach on that list, is that right?
Basically, I have a LIST that is saved in a CSV file, and I need to remove a particular record after using the search feature (which populates the fields from the CSV file... i.e. ID, Name, etc...).
I am able to get the details that are in the text fields by using a search feature. This is then put in:
logic.remove(tempIndividual)
In class myLogic.cs, then I have this method:
this.individual.Remove(tempIndividual)
Upon debugging, I can see that tempIndividual is populated with the correct data. However, I need to remove this data from the CSV file. Am I on the right track, or totally off? Maybe it is not complete, cause I can't get to the part where it actually removes the data from the CSV, or at least I'm not sure if .Remove is able to do it on its own.
Today I am refining my skills on graph theory and data structures. I decided to do a small project in C++ because it's been a while since I've worked in C++. I want to make an adjacency list for a directed graph. In other words, something which looks like: 0-->1-->3 1-->2 2-->4 3--> 4-->This would be a directed graph with V0 (vertex 0) having an edge to V1 and V3, V1 having an edge to V2, and V2 having an edge to V4, like this:
V0----->V1---->V2---->V4
|
|
v
V3
I know that in order to do this, I will need to create an adjacency list in C++. An adjacency list is basically an array of linked lists. Okay, let's see some pseudo C++ code:
Code:
#include <stdio>
#include <iostream>
using namespace std;
struct graph{
[Code] ....
This pseudocode is currently far from the mark. And that is what -- pointers and structs in C++ have never been my strong suit. First of all, this takes care of the vertices that a vertex points to -- but what about the vertex itself? How can I keep track of that vertex? When I loop over the array, it will do me no good to only know what vertices are being pointed to, rather than also knowing what points to them. The first element in each list should probably be that vertex, and then the elements after that are the vertices it points to.
But then, how can I access this first element of the list in my main program?. I would like to be able to loop over this adjacency list to do some cool things with graphs. For example, to implement some graph theory algorithms (sorts, shortest paths, etc) using the adjacency list representation. (Also, I had a question about the adjacency list. What is different than just using a list of arrays? Why can't I just have a list with an array at each element in the list?)
I am having some difficulties knowing how to assign city to the list.
Code:
class DestinationList
{
private:
int num;
// number of objects in the list
Destination list[MAX_CITIES];
// array of destinations
public:
[Code]...
i just need clarification on if this is what is considered a dynamic list of characters, i don't want a linked list.
Code:
struct dlist {
int size;
int maxsize;
char *datafield;
};