C++ :: Function To Initialize Double Data Array Element To 0.0
Apr 25, 2013ok here is the question: Write a function that will initialize a double data array element to 0.0 ?
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C++ :: Initialize String Data Members As Nullptr Or As Zero-size Array?
Nov 4, 2014Is it generally better to initialize string data members as nullptr or as a zero-size array?
I can understand the former is superior from a memory-use perspective and also not requiring the extra allocation step. However, many string management functions will throw an exception - wcslen for instance - if you pass them a null pointer. Therefore I am finding any performance gained is somewhat wiped out by the extra if(pstString==nullptr) guards I have to use where it is possible a wchar_* may still be at null when the function is called.
C++ :: How To Initialize Function Prototype Of Array With Zero
Apr 23, 2014We can initialize normal function prototype's parameters with zero like this:-
void output(float = 0.0, int = 0);
or
void output(int = 0, int = 0, double = 0.0);
But how do you do the same for a pointer array or simply an array?
Assume that second parameter has to be an array.
I have tried the following and it does not work:-
void output(float = 0.0, int = 0);
void output(float = 0.0, *int = 0);
void output(float = 0.0, int* = 0);
void output(float = 0.0, int[] = 0);
void output(float = 0.0, int []);
But if I skip the default declarations altogether, it works.
like:
void output(float, int []);
or
void output(float, int*);
how can I do it by explicitly writing zero, just like the first cases?
C++ :: Possible To Use Data Type Double Or Float For Array?
Mar 9, 2014Can you use data type double or float for an array? ie
double n[];
or
float a;
float m[a];
My code wont accept me changing the data type..will on accept int data type. I get the following error when I try to change the array to double or float..
3310E:C++vector.cpp[Error] invalid types 'double [1000][double]' for array subscript
C++ :: Linked List - Function Which Deletes Element If Next Element Is Bigger
Mar 10, 2014So I have linked list and function which deletes element if next element is bigger, so my code is working but its not working with first element, in the comment I have wrote code which I would code for checking that first element, but when ever I check it is blowing up all program.
#include <iostream>
using namespace std;
struct llist {
int x;
llist *next;
[Code] .....
C++ :: Remove Element From Array By Using Function?
Jun 2, 2013how i can remove element from array by using function?
View 3 Replies View RelatedC++ :: How To Send A Pointer To ONE Element In 2D Array To Function
Feb 2, 2015I am trying to do this.
if (isInteger(&(tokens[i][j])) == true || isDouble(&(tokens[i][j])) == true)
Instead of sending the address of the element at row I and column j, it send the address of the entire row I. What is wrong?
C++ :: Binary Search Function - Return True If Element Inputted By User Found In Array And False If Not
Nov 9, 2014I was instructed to write a binary search function which would return true if an element, inputted by the user, was found in the array, and false if it was not. I'm not sure why, but my function always returns false. My code is as follows.
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
//binary search function
bool search (int array[], int item)
[Code] ....
Why my code does not fulfill it's purpose???
C :: Initialize Data Member In Struct
Mar 28, 2013I was looking at some linked list material and was wondering something. Can you initialize a data member inside a struct like in C++? i.e.
Code:
typedef struct node
{
int data;
struct node * next = NULL; // this is the line in question
} LLnode;
C++ :: Can't Initialize Static Data Member In The Class Definition
Apr 17, 2013"You cannot initialize the static data member in the class definition — that’s simply a blueprint for an object and initializing values for members are not allowed. You don’t want to initialize it in a constructor, because you want to increment it every time the constructor is called so the count of the number of objects created is accumulated."
Why don't you want to initialize it in a constructor?
Edit: Because every time it is called it will set it back to 0 or whatever the initializing value.
C++ :: Why Can Initialize Array Nested In Structure Like Array
Feb 7, 2015Example :
Code:
struct x {
int v[4];
};
const x test = { 0, 1, 2, 3 };
Why can I do this? How does the compiler know to write to this in the proper way? I get that v would be contiguous. Does that have something to do with it?
C/C++ :: How To Initialize Array Of Pointers To Array Of Characters
May 21, 2014I am trying to initialize an array of pointers to an array of characters, I can do it in 3 lines but I really want to do it in one line at the same time keeping the #define.
3 lines initialization (can compile)
======================
#define A 1
#define B 2
char row1[] = {A|B, B, A};
char row2[] = {B, A};
char *test[]= {row1, row2};
1 line initialization (failed)
===============================
char *test[] = { {A|B, B, A}, {B, A} }; // <- how do i do this??
I do not want this because it waste ROM space
=============================================
char test[][3] = { {A|B, B, A}, {B, A} };
C++ :: Initialize Array In A Constructor?
Dec 6, 2013There are two class.How can I initialize an array of different class in a constructor?
class Ticket{
private:
int ID;
[Code]....
I have to provide a no-argument constructor (Cinema();)to initialize the ticket array and give the right ticket ID.
C/C++ :: Initialize Array With Tiles?
May 8, 2014imagine you have a world class. Than you have a tile class. Now, in the world class is a array with a lot of tiles and I want to initialize them with my imagination(For example I want a grass floor). But how I can do this, the array can only be create with the standard constructor. But it would be stupid and not very fast, that the tiles are first initialized with the standard constructor and than overridden to build the world. Whats the best way to initialize such a array ?
View 12 Replies View RelatedC/C++ :: What Data Type Is The Result Of Calculation On Int And Double
Jun 24, 2013okay for instance
int x = 4;
double y = 2;
printf("%d", (x / y + 5));
what data type is
(x / y + 5)
??
C++ :: How To Take Size Of Array And Initialize It On Heap
Feb 6, 2014I am creating a class that has a private array on the heap with a constructor that takes the size of the array and initializes it on the heap. Later I have to make a deconstructor delete the space and print out free after.In my code, I was able to heap a private array and make a deconstructor, but I don't know how to take the size of the array and initialize it on the heap. My guess is this:
int* size = new int();
Also when you initialize size on the heap, don't you also have to delete it too? If so, where, in the code, do you do that? Here is my code so far.
Class Student {
private:
int size;
int* array = new int[size];
public:
Student(); // Constructor
~Student(); // Deconstructor
[code]....
How do you make a constructor that takes the size of the array and initializes it on the heap
Student::~Student()
{
delete[] array;
cout << "Free!" << endl;
}
C++ :: Can't Initialize String Array In Constructor
Jul 22, 2013I am currently practicing designing classes. In one exercise, I am trying to store 15 words in an array, and randomly print one (using the rand() functions and seeding it with crime. I have a header file, a respective .cpp file, and a main .cpp file. When I try to compile the code using g++ GuessWord.cpp UseGuessWord.cpp -o UseGuessWord, I get the following error in my constructor: expected primary-expression before ‘{’ token
Here is my code:
header file (GuessWord.h):
#ifndef GUESSWORD
#define GUESSWORD
#include <string>
using namespace std;
[code].....
C/C++ :: String Out Of Bound - How To Initialize Array
Mar 7, 2014I'm a newbie to C++ and I am writing a code that searches strings and checks their value. I'm mostly working with if statements.
My code tends crash on Dev C++, even when I haven't recently saved any changes or compiled it, citing "memory access errors".
I recompiled in visual studio, and visual studio told me I have string out of bound errors.
My code is very long... but most of it is copy and pasted with slightly different conditions.
I believe the problem lies in how I initialize arr[4] ??
#include <cstdlib>
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main() {
cout << "Hall symbol -- generator matrix program" << endl;
// Setting up a data structure bc a normal array cannot handle the data for the spacegroups
[Code] ....
C/C++ :: Constructor To Initialize Each Members Of Array?
May 3, 2014Need a C++ constructor to initialize each members of an array. how to give value for for each elements of an array declared as a class object according to the users input.
View 1 Replies View RelatedC/C++ :: How To Initialize Array Of Structures At Runtime
Aug 26, 2014I somewhere read "You cannot initialize a structure like that at run time."
Example:
struct item_info {
char itemname[15];
int quantity;
float retail;
float wholesale;
[Code] ....
But if you want to assign values at run time then you have to do it manually like:
strcpy(item[0].itemname, "rice");
item[0].quantity = 10;
item[0].retail = 40;
item[0].wholesale = 30;
I tried in internet but am unable to know the differences. I want to know the difference between those two in terms of run time and compile time. Explanation required also for below one. Is this run time or compile time? How does we actually decide which is run time and which is compile time!
struct item_info {
char itemname[15];
int quantity;
float retail;
float wholesale;
//int quatityonorder;
[Code] ....
C++ :: How To Initialize Array Of DirectX9 Objects
Jan 3, 2015I've got an error saying that there is an access violation at 0x0000040 error no 0xC0000005
I've searched the net, saying the error may be due to an uninitialzed variable.I debugged the code, and found out that an object created from directx D3DXMATRIXA16 is uninitialized.With values ??,??,?? in each element
pMeshContainer->pBoneMatrices = new D3DXMATRIXA16[g_NumBoneMatricesMax];
here, pMeshContainer is a variable passed into a function called GenerateSkinnedMesh by pointer
GenerateSkinnedMesh(..., D3DXMESHCONTAINER_DERIVED *pMeshContainer)
Then in turn, GenerateSkinnedMesh is called within a callback from a DirectX9 API called
ID3DXAllocateHierarchy
Code:
class CAllocateHierarchy : public ID3DXAllocateHierarchy {
public:
STDMETHOD( CreateFrame )( THIS_ LPCSTR Name, LPD3DXFRAME *ppNewFrame );
STDMETHOD( CreateMeshContainer )( THIS_
LPCSTR Name,
[code]....
when the method CreateMeshContainer finished execution, the meshContainer is passed back to its parent like this
*ppMeshContainer = pMeshContainer;
The whole meshContainer stuff is stored persistently inside the frame root wrapped within a class called CMesh So in that process, I haven't initialized pBoneMatrices in anyways. But what and where is the best way to initialize an array of DirectX9 objects.
There is a function called
D3DXMatrixIdentity(&...);
But how can I initialize each one of them with this call?
Notice that pMeshContainer->pBoneMatrices does contain a valid address, despite the fact that the elements inside it are never initialized...
C++ :: How To Convert String To Double Without Changing Actual Data
Jun 3, 2013I have to convert string to double. i'm using "atof" function to achieve same.
I have string as "0.0409434228722337" and i'm converting with "atof" But i'm getting double value as "0.040943422872233702". Why it adds 02 additionally at the end?
More example :
"0.0409434228722337" converts to "0.040943422872233702"
"0.067187778121134" converts to "0.067187778121133995"
Is there any other possibility to convert string to double without changing data ?
C :: Initialize Array Values With 0s Or Assume They Will Be Initialized To 0
Apr 7, 2014The following:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[]) {
int i;
int arr[3];
[Code] ....
Notice we didn't set a value for second index but it returns 0. Should I assume that when declaring an array with n values, those values will be initialized to 0 automatically or should I still initialize the array with all 0s doing something like this:
Code:
for(i=0;i<sizeof(arr);i++) {
arr[i]=0;
}
C :: Initialize Dynamically Allocated Array Of Integers To Zero?
Jun 22, 2013Suppose I wished to initialize a dynamically allocated array of integers to zero. Would I do better to use calloc() or malloc + iterate over all entries setting each to zero? Which one is regarded as a better approach?
View 12 Replies View RelatedC :: Initialize 1D Or 2D Array In Shared Memory (POSIX)
Dec 8, 2014I am trying to initialize a 2D char array of strings into POSIX shared memory to be shared between 3 other processes. There are plenty of tutorials on how to use a pointer to share a single string or an integer between processes, but I could find no examples on how to initialize 1D or 2D arrays using mmap(). I have posted what I have so far below. It is the first program, which creates the shared memory object and initialize the array char files[20][2][100] with the value files[0][0][0] = ' '. What is the proper method to initialize and share an array in C?
(program initializes shared memory object and array)
Code:
#include<fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
int main (int argc, char *argv[]){
[Code] ......
C++ :: Initialize Char Pointer Array In Struct
Nov 28, 2014I am trying to store data in a struct to be able to read it latter . have problems initializing this.
struct FoodAndDrink {
struct Food {
char* CannedGoods[2] = {
"Canned Spaghetti",
"Canned Tuna",
[code] .....