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Passing private member pointer to Unmanaged Function C++/CLI
I may be wrong but your getter returns a copy of the pointer. So when you use &ptr you are actually pointing to a copy of the original pointer so you will change the copy but not the original pointer in your myObj instance. If you can't change the implementation of MyStructWrapper, e.g. by returning a reference to the pointer, you may not be able to do what you want. Wait for the gurus to have a definitive answer...

Categories : Dotnet

Passing array of float pointers into VBO
What you're doing is wrong because in C everything is passed by value, so when you dereference the .x member of the returned struct, you're doing it on a copy of the position struct, which will be popped from the stack if not assigned to any value. You're design is wrong, you don't need a struct like this one: typedef struct { float *x, *y, *z; } point; Rather one like this: typedef struct { float x,y,z; } If you still want to assign it to it's original value, in a way that if the original struct's values change, also this struct is changed, then you need a getter who will return a pointer to the struct, and hold a pointer to it: points[i] = [[particles objectAtIndex:i] getPositionPointer]; This way you're sure that your struct contains the same values of the orig

Categories : Objective C

Passing string to a function in C - with or without pointers?
An array is a pointer. It points to the start of a sequence of "objects". If we do this: ìnt arr[10];, then arr is a pointer to a memory location, from which ten integers follow. They are uninitialised, but the memory is allocated. It is exactly the same as doing int *arr = new int[10];.

Categories : C

Passing pointers as function arguments
Edit: true - those are pointers to const char... and so the pointer itself is not const. You're trying to change what the pointer points at - the function gets a copy of the contetnt of the original pointers so you need to either have a pointer of pointer or use a reference. ie: C void order( const char **first, const char **second ) { const char* temp = *first; *first = *second; *second = temp; } C++ void order( const char *&first, const char *&second) {} (the content is the same as your function)

Categories : C++

C - Changing the value of a variable outside of a function by passing pointers
I believe, as pointed out in a comment, that you're missing the intention. I think the idea is that the "root" stackT instance should be a well-known structure, so that you can declare one locally. Then you call init() to set up the actual stack described by the stackT instance: int push_four(void) { stackT my_stack; init(&my_stack); push(&my_stack, 1); push(&my_stack, 2); push(&my_stack, 3); push(&my_stack, 4); } The above assumes that the stack stores integers, i.e. the allocation inside init() should be something like: void init(stackT *stack) { stack->items = malloc(64 * sizeof *items); stack->count = 0; } And this, in turn, assumes a declaration like: typedef struct { int *items; size_t count; } stackT; Of course, the default ma

Categories : C

Passing function pointers as an API interface to a compiled library
You have full access to the C code. You have limited access to the C++ library code. The C code is defining the "doUsefullthings" function. From C code you are calling the "Something" function ( C++ class/function) with function pointer to "doUseFullThings" as the argument. Now the control goes to the C++ library. Here the various arguments are allocated memory and initialized. Then the the "doUseFullThings" is called with those arguments. Here the control transfers back to the C code. In short, the main program(C) calls the library(C++) and the library calls the C function. One of the requirements is that the "userland function should have access to local variable from the C code where it is called". When you call "something" you are only giving the address of "doUseFullThings". There is

Categories : C++

How to handle passing/returning array pointers to emscripten compiled code?
The expected format of Module.cwrap does allow for 'array's to be passed into the function, but will assert on result and fail if you attempt to return an array displayArrayA=Module.cwrap('displayArray','array',['array']) displayArrayA([1,2,3]) // Assertion failed: ccallFunc, fromC assert(type != 'array') A second restriction of this is that incoming arrays are expected to be byte arrays, meaning you would need to convert any incoming double arrays into unsigned 8-bit numbers displayArrayA=Module.cwrap('displayArray','number',['array']) displayArrayA(new Uint8Array(new Float64Array([1,2,3]).buffer)) Calling the method this way will invoke your function, temporarily copying your arrays to the Emscripten stack which will be reset after your invoked function's execution, making the ret

Categories : Javascript

Passing byte reference to unmanaged cpp COM dll from c#
Your com objects method take pointer to byte , but what you pass is only the first item of the byte (nativeByte[0]) which is wrong , call the method like this bool result = feg.SendPacket(ref UIdestID, ref nativeByte, nativeByte.Length); ALso did you see in the intellisense what are the arguments the method is expecting when you type feg.SendPacket , which will help you in deciding whether to add ref keyword or not for arguments.

Categories : C#

Sending array of pointers to function
Given the API entry (copied from your comments into the question), and your variable declaration, you can't pass an array of pointers to the function. You could write: GLuint buffer[2]; glGenBuffers(2, buffer); You could write: GLuint *buffers[2]; buffers[0] = malloc(number * sizeof(GLuint)); buffers[1] = malloc(number * sizeof(GLuint)); glGenBuffers(number, buffers[0]); glGenBuffers(number, buffers[1]); Either of these respects the API.

Categories : C

C++ how to pass array of pointers to a function
class base { public: int a; }; void function (base ** pool) { for (int i = 0 ; i < 40; ++i) cout<<pool[i]->a<<' '; } int main() { base *pool[40]; // Allocate 40 base objects and the 40 base pointers // point to them respectively for(int i = 0; i < 40; ++i) { pool[i] = new base; pool[i]->a = i; } function (pool); // free the 40 objects for(int i = 0; i < 40; ++i) delete pool[i]; return 0; } I added the a member just as an example. Even better would be void function (base ** pool, int n) { for (int i = 0 ; i < n; ++i) cout<<pool[i]->a<<' '; } and function (pool, n); It's not so easy to pass a copy of the array - especially in the c

Categories : C++

initalize an array of structs with function pointers in them C
One One mistake I an find, in structure declaration of function pointer is incorrect: typedef struct{ char str[512]; int (*fptr)(); // not char* fptr } infosection; Two declaration: infosection section[] = { ("Software", *SoftwarePtr), ("Hardware", *HardwarePtr), } Should be: infosection section[] = { {"Software", SoftwarePtr}, {"Hardware", HardwarePtr} } Remove *. and replace inner ( ) with { }. three: infosection section[]; section[0].str="software"; // compiler error section[0].fptr=SoftwarePtr; Is wrong you can't assign string in this way. you need to use strcpy() as follows; strcpy(section[0].str, "software");

Categories : C

How to pass a multidimensional array of pointers to a function?
Multidimensional arrays are not managed in C++, you must declare your function as: void ord_matrix_multiplication(Cache& cache, Block* block1, Block* block2, Block* block3, int* A, int* B, int* C, int i, int j, int k, int n, int s) Thereafter you may index into those arrays in a multidimensional fashion, although you are responsible for data integrity and bound checking. Additionally, it is not standard C++ to be able to declare arrays of variable sizes. The sise of the array must be known at the time of declaration, or allocated in an initialization function using the 'new' keyword.

Categories : C++

returning array of char pointers from a function (c++)
Returning objects allocated in the automatic storage (also known as "stack objects") from a function is undefined behavior. When you need to return an array in C, you have three options: Return an object allocated in the static storage area, Return an object allocated in the dynamic storage area, or Take a buffer and max size, and return the actual size of the array. The first option is rarely applicable, because it makes your function non-reentrant. The third option is widespread, but it has limitations: when you must return more data than fits into the buffer, the API needs to be called multiple times. This leaves us with option number two: use new to allocate the memory that you are returning, copy the data into it, and return the result to the caller. It is now caller's responsibi

Categories : C++

how to pass array of pointer of pointers to a function?
I made some edit and realized your function will do the same. So go on, and read the EDIT if you don't know how it works. Besides I think there's something wrong in your main(). First, array[size] = (char *)malloc(sizeof(len)); tends to report an error because no size is defined here. Second, if by size you mean the number of elements in array, then array[size] would cause an overflow. Third, the argument of malloc should be sizeof(char)*len, not sizeof(len), since the latter equals sizeof(int). Change your function to void function(char **, int); And call it by function(array, 0); EDIT I think by "modify it" you mean to change the pointers stored in the array. Since every element is a char*, a char** will do the job. When you pass array as an argument, actually you're passing

Categories : C

Array of function pointers to member functions
The dot (member-of) operator is used for accessing members of an object. For classes and namespaces, you have to use the :: operator. Also, don't parenthesize, since & has lower precedence than :: and it's more readable like fptr[0] = &operate::add;

Categories : C++

Function declaration error - returning an array of pointers
Returning an array is not something you can do in C++. Your function actually returns a pointer to the first element of ans, which is also bad news, since that array is declared on the stack and goes out of scope as soon as the function returns. The right thing to do would be to pick an appropriate data structure from the C++ standard library and use that. If for some reason you're set on fundamental types, you'll need to come up with a different solution - perhaps allocating the array dynamically inside your function and returning a pointer to it, for example.

Categories : C++

warning: initialization from incompatible pointer type - how to initialize array of struct containing function pointers
int CRChndshakeMake(PktDescriptr usbPkt, ringbuffr* usbPktpload, int* CRCcalc) does not match your declaration; typedef int (*CRCchecker)(PktDescriptr, ringbuffr, int); It's apparently disagreeing on some pointers.

Categories : Arrays

Passing an array of strings from a function to main function (C code)
Copy keywords to a linked-list and return it to main. This way you can iterate and print them in main. Also, you will not have to know before hand what size the list of keywords will be. Make sure that you copy the keyword string libxml returns into the linked-list node and xmlFree free it to avoid issues with memory management.

Categories : C

Passing 2dim array through an median function to the one of 2 other function
case 0: proc1(int iArray[][2]); break; The call should be simply proc1(iArray);. You already know enough to write selectfunction(A); and not selectfunction(int A[][2]); - you should call proc1 and proc2 the same way. Also, the statement cin;: I'm not sure what you wanted it to do, but be aware that it does nothing at all.

Categories : Visual C++

what are the initial values of pointers in "array of pointers"?
There is no requirement in C that any local variable should have any 'default' value. So, when the compiler reserves two (or three) memory locations, the initial value is whatever that these memory locations contained before - there will not be any default initialization.

Categories : C

Passing an array to a function as array vs as a pointer
This line: printf("address of array passed in: %p ", &x); Is wrong. You are not printing out the address of the array, but the address of the local variable that the array pointer is stored in. (Yes, x is actually a pointer.) Just print out x: printf("address of array passed in: %p ", x); The answer is that in this case it doesn't matter much which way you declare it. int[] and int* in C are sometimes interchangeable, and this is one of the cases where they are. Further reading: Are pointers and arrays equivalent in C? (Specifically, see the "arrays passed to functions are converted to pointers" section.)

Categories : C

Passing array to a function
void func(int *arr) void func(int arr[]) void func(int arr[5]) are all equivalent in C. C says a parameter of an array of type is adjusted to a pointer of type.

Categories : C

C++ Passing array into function
You are passing a copy of the array, so any changes will not affect the original. Pass by reference instead: void addToArray(Array<int> &intarray) // ^

Categories : C++

C# pointer to unmanaged struct with array
Use Marshal.PtrToStructure: var bytes = yourUnmanagedByteArray; fixed (byte* b = bytes) return (T)Marshal.PtrToStructure(new IntPtr(b), typeof(DivertIPv6Header)); You could make it work without a fixed buffer too, if you don't want to use unsafe code.

Categories : C#

Passing an array through a function's parameters
You can use $.each like this : $.each(["one_a", "one_b", "one_c"], function(_,shape) { $('.'+shape).mouseover(function(){ $('.main_box').addClass(shape); }).mouseout(function(){ $('.main_box').removeClass(shape); }); }); Note that I changed your code so that the mouseout event is only bound once. You might also be interested in the hover function.

Categories : Javascript

C: passing an array (pointer) to a function
As you already knows the number of rows = nline in your matrix in count0 function. So you should simply allocate all memory for array a in count function one time, you don't need to re-call realloc() function. void count0(int **M, int col, int** a){ (*a) = malloc(nline * sizeof(int)); for(i = 0; i < nline; i++){ (*a)[i] = M[i][col]; } } Note: precedence of [] is higher then * so you need () around *a just call this function as: count0(H, col, &b); and free(b); in main() after printf statement to deallocate memory explicitly.

Categories : C

Passing char array to function
static const char* hello_str = "hello" will do it. Replace sizeof() with strlen. Maybe this should have been a comment as I am not explaining the fundamentals of pointers, but I actually do not see a point :) in doing that as there are plenty of info on that subject elsewhere.

Categories : C++

Function error, passing as array
You declared svname as a local variable in addition to a function. Remove the second declaration and it should work: Dim resp As String', svname As String <- error caused by this bit

Categories : Excel

VB.NET passing array of strings to a C function
Basically, create some pinned memory to store the strings, and pass that to your function: Marshal.AllocHGlobal will allocate some memory for you that you can give to your c++ function. See http://msdn.microsoft.com/en-us/library/s69bkh17.aspx. Your c++ function can accept that as a char * argument. Example: First, you'll need to convert your strings to one large byte[], separating each string with nulls (0x00). Let's do this efficiently by allocating just one byte array. Dim strings() As String = New String() {"Hello", "World"} Dim finalSize As Integer = 0 Dim i As Integer = 0 Do While (i < strings.Length) finalSize = (finalSize + System.Text.Encoding.ASCII.GetByteCount(strings(i))) finalSize = (finalSize + 1) i = (i + 1) Loop Dim allocation() As Byte = New Byte((finalS

Categories : C++

Passing an Array with Objects to another function in GAS
As a complement to the answer I gave in the comments : "you could also simply store the id and while you read the events again using the same start/end time you can check if an event correspond to the saved ID in a loop... if a match is found with the right ID you are sure it's the right event" Here is a piece of code I use to modify/update/delete calendar events using their ID as reference. This code is used to delete specific events selected from the spreadsheet, the code to modify events is roughly the same, at least it uses the same ID checking. ... var cal = CalendarApp.openByName(calName); if (cal) { var events = cal.getEvents(new Date(date_deb), new Date(date_fin),{max: 4000}); // stocke tt ds une variable array var sel= sh.getRange(6,1,sh.getLastRow()-5, 10).getVal

Categories : Arrays

Passing pointer array to function
It is UB to use malloc to allocate non POD types, in your case book instances will contain some garbage in strings, because there was no std::string constructor called. And it won't be just garbage strings, it will be most likely garbage pointer pointing to some random locations. You should use std::vector or at least new if you really need to allocate memory manually, to create new Book instances in a heap. And if you really, really must use malloc, you can use placement new to create valid std::strings in raw memory you have allocated somehow (by malloc in your case).

Categories : C++

passing bool array to a function
When you pass an array to a function, in fact you pass the pointer to the first element. That's why the changes that you do to the array in the function are reflected in the original array. You cannot pass an array by value. This is because: Copying arrays would be kind of complicated and not very clear, since the behavior would change for different parameters and different function declarations. Why can't we pass arrays to function by value?

Categories : C++

passing array to recursive function
for that you need to delete the values you've put in the array, by adding the line a[x + 1]=0; after the recursion call: #include<iostream> using namespace std; int a[100]; void go (int a[100],int x) { a[x]=x; for(int i=1;i<=5;i++)cout<<a[i]<<" ";cout<<endl; if(x==3)return; go(a,x+1); a[x + 1]=0; for(int i=1;i<=5;i++)cout<<a[i]<<" ";cout<<endl; } main() { go(a,1); } also you don't need an array of 100, or an array at all, you can just do: #include<iostream> using namespace std; void go (int x) { for(int i=1;i<=5;i++)cout<<(i <= x ? i : 0); cout << endl; if(x==3)return; go(x+1); for(int i=1;i<=5;i++)cout<<(i <= x ? i : 0); cout << en

Categories : C++

C++ Passing an new array to a pointer from a function
You're right, because r is declared on the stack it will be deleted when it goes out of scope. You need to allocate memory on the heap e.g. int *r = new int[7]; // * was missing make sure you call delete [] ris; when you're done using it, to free the memory you allocated

Categories : C++

Proper calling convention of unmanaged DLL function
Not much point in declaring the argument type if only NULL is permitted. Just declare it IntPtr and pass IntPtr.Zero. The debugger is pointing out that you forgot to declare the CallingConvention. It is not the default for .NET, this is a __cdecl function. So the proper declaration would be: [DllImport("libvlc", EntryPoint = "libvlc_new", CallingConvention = CallingConvention.Cdecl)] public static extern IntPtr New(int argc, IntPtr argv); Called as: New(0, IntPtr.Zero); Do try to pick a better name...

Categories : C#

Passing a 2 dimensional array to a function using a pointer in C++
If I remember correctly you can use something like 'string [][] & rArray' (or exactly: string [3][3] & rArray), of course you should pass the actual dimensions as parameters as well. The compiler accepted this: string arr2[3][3] as parameter. But i would try to improve passing a pointer instead of copying an array by value. Since you are using stl::string you could also try vector< vector< string > >.

Categories : C++

passing an integer and an array of integers to a VBA function
Try below code: Public Sub mainSub() Dim IsMember As Boolean b = Array(4, 5, 6, 7, 8, 9) Dim checkVariable As Integer checkVariable = 4 IsMember = ckArr(checkVariable, b) If IsMember Then MsgBox checkVariable & " is a member of member of array" Else MsgBox checkVariable & " is not a member of member of array" End If End Sub Public Function ckArr(N As Integer, A As Variant) As Boolean For i = LBound(A) To UBound(A) If N = A(i) Then ckArr = True Exit Function End If Next End Function B = Array(4, 5, 6, 7, 8, 9) so B is variant here. So i have made parameter of below procedure as variant. From Public function ckArr(N As Integer, A() As Integer) To Public Function ckArr(N As Integer, A

Categories : Excel

Passing a std::array of unknown size to a function
Is there a simple way to make this work, as one would with plain C-style arrays? No. You really cannot do that unless you make your function a function template (or use another sort of container, like an std::vector, as suggested in the comments to the question): template<std::size_t SIZE> void mulArray(std::array<int, SIZE>& arr, const int multiplier) { for(auto& e : arr) { e *= multiplier; } } Here is a live example.

Categories : C++

Passing a Variant Array from Excel VBA to a WCF Function
I have similar problems with Type mismatch error only if I declare array variable in VBA in this way: Dim anotherArray() As Variant but the error disappears if the variable is defined in this way: Dim anotherArray As Variant Some other differences between your and my similar solutions are: //C#- my solution- without array[] definition: public object[] ReturnSomeArray(object someArray) //VBA- my solution -without array() definition: Dim someArray As Variant EDIT: 2013-08-28 Working with C#-Excel-Interop I prefer try&test way of searching solution. If anything works then I stick to it and sometime I miss to indicate the source of the solution or logic. Below you will find code which includes LINQ to operate with arrays. These code snippets works in both direction- get data f

Categories : C#

C++ passing dynamic array element to a function
You cannot return a raw array like that. What your fInit() does is to return the address of some local memory that is invalidated once the function returns. Your a then, in some sense, points to memory inside your fInit(), but which is not valid anymore. Any attempt to read an element a[n] results in undefined behaviour. You should use one of the standard containers, e.g. a std::vector if the size of the array is determined at runtime, or std::array if you know the size at compile time. If you need chained lists, use std::list, and so on. All of the standard containers are copyable (and thus returnable). See http://en.cppreference.com/w/cpp/container. And, definitely bookmark http://en.cppreference.com/w/. And every time you are tempted to write yourself an algorithm, or find yoursel

Categories : C++



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