Can I a have one pointer with two reference in it. Here's what I've got.
Code:
char* c;
char x='x' , y='y';
c = &x;
c = &y; -- or --
Code: char* c[2];
char x='x' , y='y';
c[0] = &x;
c[1] = &y;
If it's possible I want to apply it to make AST.
i really don't know why has a error in my code, that pass a pointer of pointer (name of a matrix with 2 dimensions). Here is the source code of a simple example where appears segmentation fault when execute (but compiles normal):
#include <stdio.h>
#define LINHAS 3
#define COLUNAS 5
float a[LINHAS][COLUNAS];
void zeros(float **p,float m, float n){
int i,j;
for(i=0;i<m;i++)
[Code]...
Essentially, the 'Sequence' below uses linked lists to store data. If 'result' refers to the same sequence as 'seq1' or 'seq2', I want 'result' to refer to a new sequence. This new sequence can be default constructed (no copy of 'seq1' or 'seq2' is required). I can't seem to do this correctly. Also, the prototype of the function cannot be altered.
void fun(const Sequence& seq1, const Sequence& seq2, Sequence& result) {
// Check for reference to same sequence. If they are the same,
// create new sequence for 'result' to refer to
if ((&seq1 == &result) || (&seq2 == &result)) {
[Code] ......
I would like to get the this pointer by call by reference. Is this possible? I hoped to get it with this code, but it doesn't work:
Code:
"cpp"]class DemoClass {
public:
DemoClass();
int x;
void setParam(const DemoClass ¶m){
param=this;
[Code] ....
I get always the error code "C2678". But I don't understand how I should change my code to avoid this.
I am used to the restrict keyword to hint the compiler that no overlap is going to happen in the values passed to the function.
void foo( int * restrict a, char * restrict b)
I understand that I can pass by reference in c++.
void foo( int &a, char &b)
Using it, will it automatically restrict it or not ? It is very important for performance reasons (no checks at each iterations/steps)...
//program to form a header file
/* using pass by reference in pointer */
#include <iostream>
#include<math.h>
[Code].....
I am unable to get "reference to a pointer".
Here:
char*p = "hello";
char*&k = p;
while creating reference to a pointer why we have to write *&k , why not &*k?
I've read about the difference between the two, what one can do that the other can't syntactially, but I'm still very confused by the concept of references in C++. I'm trying to understand what is the difference in terms of undelying implementation.
Take, for example, the following code:
void foo(int *bar) {
++*bar;
}
int main(void) {
int n = 0;
foo(&n);
return 0;
} Translated into: Code: __Z3fooPi:
[Code] ....
Considering the above assembly code, and the memory that was used in both cases, I'm tempted to say that references was added to C++ to make the synax looks prettier... Where would I be wrong?
What is the difference in pass by pointer and pass by reference? As per my understanding, there is no difference much.If a function accepts pointer, then NULL check can be performed.other than this i'm not able to see any big difference..
View 3 Replies View RelatedI have a struct which has an array inside of it:
struct someStruct{
int structArray[999];}
Now when I want to access that array, I have the following:
ptrSomeStruct->structArray[someIndex];
But now I want to pass structArray to this function by reference so that it can adjust the array as needed and I can continue to use the array back in my caller function:
void adjustArray(void *& someArray){}
How do I accomplish this?
I just want to know if there is any real difference between the two below, if yes, when would i use one over the other? I would thought the "&" is pointless in below function, as far as the data is concerned.., the only things is with "&", if the pointer address value is changed in Test function, it will affect the caller's copy of data. Both function should behave the same if data is changed.
Code:
Between
void Test(QSharedPointer<Data> data)
{
}
and
void Test(QSharedPointer<Data> & data)
{
}
#include "vehicle.h"
...
void exchange(vehicle *&v1, vehicle *&v2) {
vehicle *tmp = v2;
v2=v1;
v1=tmp;
}
Is it right?
How about: void exchange(vehicle *v1, vehicle *v2){...}
What is the difference between *&v1 and *v1 ?
what is the advantage of using reference over constant pointer?
Can they be used interchangeably?
i'm still unclear between the difference between using pointer and a reference
I understood the concept of pointers in c in the class i took last year
and that was to change the actual value stored in the memory address Code:
void change_a(int a*){
a=6;
}
int main(){
int a=5;
change_a(&a);
}
but in c++ I've been using references in all my assignments because I don't know how to correctly use pointers in c++ I may have missed a class but I'm on spring break and would like to clear things up
so in c++
in my assignments I would call it like this Code:
void change_a(int &a){
a=6;
}
int main(){
int a=5;
change_a(a);
}
so does this change the value in the address or does it make another copy of a in my c++ code and stores 6 in that copy
I have to write an example in which you use a function having as argument a pointer passed by reference in C++. Can you provide an example like this:
funz.h : void funz( int *&a );
funz.cpp : ? (1)
main.cpp:
#include "funz.h"
#include <iostream>
[Code]...
as I write in (1) and (2) ?
I don't understand how my code not run.
#include "stdafx.h"
#include<iostream>
using namespace std;
struct student{
char name[30];
char birthday[20];
char homeness[50];
float math;
[Code] ....
I just started learning about pointer and reference. * and &
The assignment is " Write a program that stores the following numbers in the array named miles:15,22,16,18,27,23, and 20. Have your program copy the data stored in miles to another array named dist, and then display the values in the dist array. YOur program should use pointer notation when copying and displaying array elements.
And this is what i have so far. But there is an error. I highlighted it with red. It says it's incompatible...
#include <iostream>
using namespace std;
const int arraynumb = 7; // declaration of keys: number of characters of keys
void copyfunc(int *[], int); // function initialized
int main() {
int miles[arraynumb] = {15, 22, 16, 18, 27, 23, 20};
[Code] ....
I am trying use a print function to print out data in a struct. My questions are:
1. I have to use pass by reference. For the print function, I am passing the struct pointer as a reference, however, I don't want the print function to accidentally change anything. How can I make it use const to ensure that?
2. The deleteprt function doesn't look right to me. I feel like it should just be delete ptr not delete [] ptr.
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <string>
using namespace std;
struct Inventory {
[Code] .....
Basically I'm trying to pass an object as a reference to the template function, rather than a copy as it's seeing. I'm needing to do this without editing Obj::Call to accommodate a reference as its first parameter, as it'd break other calls.
You'll notice in the following code the object will be destroyed upon passing, while the object defined is still in-scope due to the infinite end loop.
#include <iostream>
#include <string>
using namespace std;
class Obj {
public:
string name;
Obj(string name): name(name) {cout << "create " << this << endl;}
[code]....
In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.
In my code, I have a function like such: int function1(int* a, int* b). I am wondering how to call it in int main.
View 3 Replies View RelatedI declared all functions in header file, such as:
bool readCase();
bool meshing();
bool readMesh();
bool calculateFlowfield();
bool readFlowfield();
bool calculateEvaporation();
And then I define them in separated .cpp files, each .cpp file include the header, but I got multiple definition error, why?
Even the int main() function, which only decalred and defined once got this error, why?
I have encountered a problem I can't see to solve. I want to access a function and can't seem to find the right combination to get me there. Here is what I am looking at:
CFoo1::CFoo2::GetStrDataC(int nRow) const
How do I call the GetStrDataC function from another class?
I want to develop an application which can host multiple views of explorer (window), where as each window is totally separate from others. So that I can have multiple desktop views through my single explorer. Any built in feature in .NET ?
View 11 Replies View Relatedhow to make subroutines and return multiple arrays.Before that, i wrote my program on matlab. could my program to be structured as following?
<header>
initial value of program;
subroutine1() {
calculating the first work;
return 2 or 3 arrays;
[code].....
I've been working on a function that works like a pipeline of a shell but receives a directory, go over it an search for every file to send it to a filter, something like this in bash "cat dir/* | cmd_1 | cmd_2 | ... | cmd_N", The only problem i have with the code is the redirection of the pipe descriptors.
Code:
int main(int argc, char* argv[]){
char** cmd;
int Number_cmd;
cmd = &(argv[2]); /*list of cmds*/
Number_cmd = argc-2; /*number of cmds*/
}
[code]....
The code is seems to work fine except when i run it with more than one command in example ("./filter DIR wc rev") in this case it returns
wc: standard input: Bad file descriptor
wc: -: Bad file descriptor
0 0 0
I'm using multiple C++ files in one project for the first time. Both have need to include a protected (#ifndef) header file. However, when I do that, I get a multiple definition error.
From what I found from research, adding the word inline before the function fixes the error. Is this the right way to do this, and why does it work? Should I make a habbit of just declaring any function that might be used in two .cpp files as inline?