C++ :: Storing Numbers In Array - Pointer And Reference
Apr 17, 2012
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] ....
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May 17, 2014
#include <iostream>
#include<fstream>
int decryption(int);
int multiply(int,int[][2]);
using namespace std;
main(){
int n;
ifstream inFile;
inFile.open ("out.txt");
[Code] .....
I was trying to store numbers read from a text file into 2D array but I am getting the error above.here is where the error occurs:
line 33: cout<<m[i][j]<<" ";
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Mar 14, 2013
I 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?
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Jun 20, 2014
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]...
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Feb 22, 2013
I am working on a program which creates a large pointer array of numbers and then performs several iterations of operations in them.
Code:
int * u = new int[N];
double * nu = new double[N];
int * nud = new int[N];
for (int i=0;i<M;i++){
for (int i=0;i<N;i++){
u[i]=0;
nu[i]=0;
[Code]...
If M is small enough then there are no problems in the program. However once M is large enough I get the "unhanded exception":
std::bad_alloc at memory location 0x0026f728..
Since I am just reusing the same arrays, and since I am able to make it through a few iterations, I didn't think it could be a memory issue. If it is, is there a way I can clear the data completely after each iteration?
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Aug 20, 2014
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.
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Jan 7, 2015
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.
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Jul 7, 2014
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)...
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Feb 9, 2015
//program to form a header file
/* using pass by reference in pointer */
#include <iostream>
#include<math.h>
[Code].....
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May 12, 2012
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?
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Dec 6, 2014
I am writing trying to store a list of numbers into an integer as bits. So far I have this:
n=n & 0x0f
integer = integer<<2
integer = integer | n;
convert(integer));
I want it to store the integers as bits so that I am move them over and store them farther down the row as more numbers are added, but instead each new number is being added to the previous and I'm just getting a larger integer. Is this even a feasible way to store integers within an integer?
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Jul 12, 2014
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?
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Jan 24, 2013
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..
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Jul 30, 2014
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)
{
}
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Mar 15, 2012
#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 ?
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Jun 10, 2013
what is the advantage of using reference over constant pointer?
Can they be used interchangeably?
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Feb 9, 2013
I want to store a very small number - too small for even a long double. However, I don't need the number to be stored very precisely - in fact, all I really need is the order of magnitude of the number. For example, the number 5.205849034425 X 10^-381 can just be stored as an integer of -381 for my purposes. I don't really care about the precision of the 5.205849034425 part.
The reason I get this very small number, is because I am multiplying together thousands of numbers, all of which are around 0.0001 in value. So, one way to do this would be to store all these individual values as simply their order of magnitude (e.g. -4) and then instead of multiplying the numbers, I would just add up their orders of magnitude. However, I am wondering whether there is a way in C++ to do this without me having to change the way I store my data - I still would like to keep the original values if possible.
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Mar 9, 2013
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
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Dec 8, 2014
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) ?
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Oct 4, 2013
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] ....
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Apr 21, 2014
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] .....
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Sep 19, 2014
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.
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Oct 25, 2013
Write a function called breakThree that will accept a 3 digit integer and returns each of the numbers individually. This function will take four paramaters. The first parameter is the three digit number to break apart. Parameters 2 through 4 are passed by reference and will be used to return each of the numbers back to main.
You should make sure that the input into the function is a 3-digit number. If it is not a three digit number the breakThree function should simply return false. If it is a three digit number the breakThree function should break the number apart, and store each of the numbers in the parameters passed by reference.
In main you should get the number from input and then output each of the numbers on a separate line.
What not to use
global variables
cin in breakThree function
cout in breakThree function
goto statements
#include <iostream>
using namespace std;
void separate(int a, int b, int c, int d);
int main(int argc, const char * argv[]) {
int num;
[Code] ....
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Sep 18, 2013
How to code the following:
I have two random numbers which are generated and are related to each other (representing x and y co-ordinate). These random numbers are generated within a specified range: (-range, +range).
I want to categorize these values in a (2-dimensional) grid. The grid size is not definite and so can be varied by the user would be in the order of 400 x 400. (e.g., think CCD detector). For each random number pair (x, y) I want to store a hit (a plus one) in the corresponding grid reference.
In the order of 500,000 related random numbers (x and y) are to be generated and the position recorded according to grid reference. So code needs to be fast.
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Jul 31, 2013
Take for example two arrays.
int A[2][2][2] = { {{1, 2}, {3, 4}},{{ 5, 6}, {7, 8}} };
int B[1]
I want to store the entire array "A" into B[1]. Is it possible?
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Mar 27, 2013
I am having trouble storing strings into an array. Basically I have a console program where it has an option. This is just an example;
Code:
char name[max];
char listofnames[maxname];
int counter;
....
printf("Add names
");
And how can I print it?
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