so I'm trying to rework some code that solves sets of equations by gaussian elimination and wanted to change the array elements to pointers. Below i've put my c code and the custom header file that goes with it.
Header file
#ifndef CHAPTER5_8_H
#define CHAPTER5_8_H
#define N 5
#define INPUT_FILENAME "equations.txt"
[Code].....
The following function uses reference variables as parameters. Rewrite the function so it uses pointers instead of reference variables, and then demonstrate the function in a complete program.
int doSomething(int &x, int &y)
{
int temp =x;
x = y * 10;
y = temp * 10;
return x + y;
}
I understand how to covert the reference variables to pointers, however I am stuck on this error. Either I get the error listed in the title or (with a few changes) the error "invalid conversion from 'int' to 'int*'"
What am I doing incorrectly?
#include <iostream>
using namespace std;
int doSomething(int*, int*);
int main(){
int X, Y, result;
[Code] ....
I have multiplied both x and y by 10 and then added them together!
Here is the result " //I really didn't know how else to use the "doSomething" function in a meaningful way. So... I just stated what the function does.
<< result << ".
";
system("PAUSE");
return 0;
}
int doSomthing(int *x, int *y)
[Code] .....
I am going to read some codes about image processing and I need to understand functions like this one below?
BOOL Trans_Geo_Affine(CImage *pImgSrc, CImage *pImgDst, BOOL bMatrix,
BOOL bHvInversed, double fScale_xx, double fFlex_xy, double fSkew_yx,
double fRotate_yy, double fTx, double fTy, int nInterpolation, BOOL bResize, BYTE cFill)
[URL]
two parameters, CImage *pImgSrc and CImage *pImgDst. I think they are class pointers and the function is passed by reference. What should I learn to understand this function and its parameters? How should I use this function? how to use the function with two parameters CImage *pImgSrc and CImage *pImgDst.
If f1 and f2 are two user defined functions.
main(){
int *p;
f1(&p)
}
f1(**p){
f2(&p);//
If I've to pass the pointer by reference again in another function, will I've to do something like this?
}
f2(***p){
**p = NULL;
}
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'm trying to create an array of pointers to pointers which will point to array of pointers (to strings) I tried
Code:
int i;
char *string[]={
"my name is dave",
"we like to dance together",
"sunny day",
"hello",
[code]...
the app keeps crashing , I don't know how to make the array-elements to point to another array-elements..
I am trying to use smart pointers to sort and re-link potentially large data elements. I have defined a class in my code for smart pointers, as listed below:
template <typename T>
class sptr {
public:
sptr(T *_ptr=NULL) { ptr = _ptr; }
[Code] ....
The object I'm trying to sort is a singly-linked list containing class objects with personal records (i.e., names, phone numbers, etc.). The singly-linked list class has an iterator class within it, as listed below.
template <class T>
class slist {
private:
struct node {
node() { data=T(); next=NULL; }
[Code] .....
The following is my function within my list class for "sorting" using the smart pointers.
template <typename T>
void slist<T>::sort(){
vector< sptr<node> > Ap(N); // set up smart point array for list
//slist<T>::iterator iter = begin();
node *ptrtemp = head->next;
[Code] .....
I must have a bad smart pointer assignment somewhere because this code compiles, but when I run it, std::bad_alloc happens along with a core dump. Where am I leaking memory?
I've been given an assignment with the below questions.
1. What is the difference between pass by reference & pass by pointers?
2. What is the use of the initialization list in the constructor?
3. What is meant by a reference & its advantage?
4. Class has a reference, pointer and a const. Is it possible to write the copy constructor & assignment operator overloading funciton? how? ( Since reference is there, I'm not sure on how to write for it)
5. Example for a variable decleration and definition? (I know for function but for variable don kw how)
6. static and const static what is the difference??
Write a program using user-defined function which accepts an integer array and its size as arguments and assign the elements into a two dimensional array of integers in the following format: If the array is 1,2,3,4,5,6, the resultant 2D array is
1 2 3 4 5 6
1 2 3 4 5 0
1 2 3 4 0 0
1 2 3 0 0 0
1 2 0 0 0 0
1 0 0 0 0 0
Write a function that takes an array and returns true if all the elements in the array are positive, otherwise, it returns false.
View 6 Replies View RelatedI am having problem in writing the code for the problem "To assign the elements of 1-D integer array into 2-D array of integers such as if the array is 1,2,3,4,5,6 The resultant 2-D array should be like :
1 0 0 0 0 0
1 2 0 0 0 0
1 2 3 0 0 0
1 2 3 4 0 0
1 2 3 4 5 0
1 2 3 4 5 6
"
I have just started learning C language, I have read that array name is the pointer to the first element of array.
So,technically both a and a[0] should have different memory address and a should hold address of a[0],
But when I declare an array and print the address:
int a[5]={2,4,6,8,10};
printf("The address of a and a[0] are &d and %d",&a,&a[0]);
Output is: The address of a and a[0] are 2358832 and 2358832
Why I am getting the same result, shouldn't I be getting different memory address for both a and a[0].
Im trying to reference my array in another function but i keep getting errors.
void player::store()
{
int menuChoice;
int amountChoice = 0;
int items[4] = {0,0,0,0};
string inv;
[Code]...
errors
C:UsersChayDesktopDinosaur ArenaMainGame.h|81|error: declaration of 'items' as array of references|
C:UsersChayDesktopDinosaur ArenaMainGame.h|81|error: prototype for 'void player::backpack(...)' does not match any in class 'player'|
C:UsersChayDesktopDinosaur Arenaplayer.h|24|error: candidate is: void player::backpack()|
I'm trying extremely hard to understand pointers and I have the basic concept down.. I feel as though my knowledge of dynamically allocated pointers and pointers in general is not enough to understand the logic behind what I'm trying to do. The problem is that the donations array must be able to accept any number of donations. I've made it do just that, but there is also an array of pointers which must each point to the same element in the donations array. The program works if I assign int *arrPtr[100] for example, but it does not work if I try to dynamically allocate it to accept the same number of elements for donations entered by the user. Here it's the snippet
#include <iostream>
using namespace std;
//Function Prototypes
[Code]....
I need to pass an array of 10 instances of a custom class to a function. The snippets of code are posted below. How would I do this right?
The prototype:
Code:
int Search(Vertex vertex[], ofstream &outfile);
The implementation in the main function.
Code:
Search(vertex[10], outfile);
How can I pass a matrix as a reference parameter? I am using the following declarations:
Code:
typedef std::vector< std::vector<std::string> > ss_matrix_t;
I declare the matrix with the following statement, where nRows and nCols are integers
Code:
std::vector< std::vector<std::string> > vI2Matrix(nRows, std::vector<std::string>(nCols,""));
The function is called with:
Code:
int read_files(std::string fname, int nCols, int nRows, ss_matrix_t &ssMat )
But I get a linker error:
error LNK2019: unresolved external symbol "int __cdecl read_splayed_files(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int,int,class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > >,class std::vector<class std::vector<class
[Code] ....
I suspect the syntax of the declaration, but I am not sure what to do here? If I change the call to the function, then the array ( matrix ) is passed by value, and it takes forever:
Code:
int read_files(std::string fname, int nCols, int nRows, ss_matrix_t ssMat )
// this takes ages ( it does compile and link )
I've a file that looks like this:
84484-37.96-Castor, Kathy
39050-69.68-Chandler, Ben
26183-70.84-Costello, Jerry
I have successfully read each element the id, grade and name into 3 separate array. Now i need to add a new student with an id and grade
How do i do this?
This is what I have.
int addStudent( int Iarray[], double dArray[], string sArray[], int newID,
double newGrade, string newName, int size ) {
char ready;
int index;
cout << endl;
cout << "Enter new student ID number : ";
[Code]...
I have a question regarding the elements of an array. Suppose I have a 3 by 3 string array (char x[3][4] ) , and I initialize all the elements to x's , the array would then look like this :
xxx
xxx
xxx
I'm curious if there will be a value if I try to access and element outside the array. As I have to write a code to determine if I have reached the end of an array. The only way I can think of is to border the entire array with o's , making it look like this :
ooooo
oxxxo
oxxxo
oxxxo
ooooo
Is there any other way to do this?
I 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} };
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?
I define an integer variable and pass it by reference to a function.
int func(int &x)
{
// do something
}
int x;
func(x);
However, I have not only one variable but an array of variables with its predefined name. How do I pass to the function by using loop? Example:
int x, y, z;
func(x);
func(y);
func(z);
How can I do this by using loop?
Trying to concatenate the 1st and 2nd element from an array of chars. Then this to be used as a hex value.
so for example
specs[0]='f'
specs[1]='4'
concatenate_value=0xf4
Write the definition of a function reverse , whose first parameter is an array of integers and whose second parameter is the number of elements in thearray . The function reverses the elements of the array . The function does not return a value .
Code:
void reverse(int a[], int num) {
for ( int i=0; i <= num/2 ; i++){
int temp = a[i];
a[i] = a[num-i-1];
a[num-i-1] = temp;
} }
This is supposed to be the answer but I'm not quite sure why this is. I understand everything up until the actual loop. For one, shouldn't "int i" be declared outside the loop (I thought perhaps this was an error in the solutions)?
The main thing that I do not understand is the conditional statement.
Code: i<=num/2;
I don't understand why the "num/2" is necessary here. Also I can't really remember but is there a command that actually reverses an array?
I'm trying to set all the elements of my array to 0 but nothing seems to be working.
.h
#ifndef ServerGroup_h
#define ServerGroup_h
class ServerGroup {
public:
ServerGroup(const int&);
[Code] .....
I want to set each element of the array in servers to 0 based on what is passed into size by numArray.
I am trying to write a program that reverses the elements of an array by using an function 'myreverse'. The function should reverse original array and return nothing.
In my program, the function 'myreverse' is not getting invoked and the original array is being displayed as it is.
#include <iostream>
using namespace std;
void myreverse(int arr[],int n) {
int *p=&arr[n-1];
int temp;
for(int i=0;i<n;++i)
[Code] .....
I'm having trouble getting my array to add its values together. I have a similar program running fine with the exact same equation. I am not so naive as to believe that this means it should run with every program but I'm at a loss as to what to do.
#include <iostream>
#include <iomanip>
using namespace std;
[Code].....