pointers

STL Vectors, pointers and classes

Hey! Let's say i have 2 classes: class Class1 { public: std::vector<CustomClass3*> mVec; public: Class1(); ~Class1() { //iterate over all the members of the vector and delete the objects } }; class InitializerClass2 { private: Class1 * mPtrToClass1; public: InitializerClass2(); void Initialize() { mPtrToClass...

C++ arithmetic with pointers

I am trying to add the following: I have an array of double pointers call A. I have another array of double pointers call it B, and I have an unsigned int call it C. So I want to do: A[i] = B[i] - C; how do I do it? I did: A[i] = &B[i] - C; I don't think I am doing this correctly. Edit: What I want to do is, take the value at in...

C++ print value of a pointer

I have an array of double pointers, but every time I try do print one of the values the address gets printed. How do I print the actual value? cout << arr[i] ? cout << &arr[i] ? they both print the address Does anyone know? ...

"Initializing" the pointer in the separate function in C

I need to do a simple thing, which I used to do many times in Java, but I'm stuck in C (pure C, not C++). The situation looks like this: int *a; void initArray( int *arr ) { arr = malloc( sizeof( int ) * SIZE ); } int main() { initArray( a ); // a is NULL here! what to do?! return 0; } I have some "initializing" fun...

c++ defining a static member of a template class with type inner class pointer

I have a template class like here (in a header) with a inner class and a static member of type pointer to inner class template <class t> class outer { class inner { int a; }; static inner *m; }; template <class t> outer <t>::inner *outer <t>::m; when i want to define that static member i says "error: expected con...

C++ Pointer Issue

_stuckVertices is an array of pointers and I would like to update one index of that array without using _stuckVertices[ (row * _cols) + column ] 3 times. The reason it is an array of pointers is because the vast majority of the time the pointer will be NULL. The following code works but I need to dereference a each time I use it: void...

Code generation in Eclipse plug-in

Hi, I'm developing an Eclipse plug-in and I'd like to insert code automatically... sort of create a sample application automatically when the user presses a button. How can I go about it please? Thanks and regards, Krt_Malta ...

Official names for pointer operators

What are the official names for the operators * and & in the context of pointers? They seem to be frequently called dereference operator and address-of operator respectively, but unfortunately, the section on unary operators in the standard does not name them. I really don't want to name & address-of anymore, because & returns a pointer...

A queue in C using structs and dynamic memory allocation (linked list)

I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc ...

How to return a copy of the data in C++

I am trying to return a new copy of the data in a C++ Template class. The following code is getting this error: invalid conversion from ‘int*’ to ‘int’. If I remove the new T then I am not returning a copy of the data but a pointer to it. template<class T> T OrderedList<T>::get( int k ) { Node<T>* n = list; for( int i = ...

Why is casting Derived** to Base*const* forbidden ?

After reading this question, i saw the answer by Naveen containing a link to this page, which basically says, that casting from Derived** to Base** is forbidden since could change a pointer to an pointer to a Derived1 object point to a pointer to a Derived2 object (like: *derived1PtrPtr=derived2Ptr). OK, i understand this is evil ... B...

Call by Reference Function in C

Hello everyone, I would just like a push in the right direction here with my homework assignment. Here is the question: (1) Write a C function called input which returns void, this function prompts the user for input of two integers followed by a double precision value. This function reads these values from the keyboard an...

How to assign void* pointer1 to void* pointer2? Facing some problem

void* ptr1 = NULL; void* ptr2 = ptr1; unsigned int *buf = data;//some buffer //now ptr2 = buf + 8; The above change in address of ptr2 is not reflected in ptr1. I am trying void* ptr2 = &ptr1; too. Please let me know whats the mistake here. ...

C# memory management: unsafe keyword and pointers

What are the consequences (positive/negative) of using the unsafe keyword in C# to use pointers? For example, what becomes of garbage collection, what are the performance gains/losses, what are the performance gains/losses compared to other languages manual memory management, what are the dangers, in which situation is it really justifia...

Binary Tree in C Insertion Error

I'm quite new to C and I'm trying to implement a Binary Tree in C which will store a number and a string and then print them off e.g. 1 : Bread 2 : WashingUpLiquid etc. The code I have so far is: #include <stdio.h> #include <stdlib.h> #define LENGTH 300 struct node { int data; char * definition; struct node *left; struct node *...

not so obvious pointers

I have a class : class X{ public : void f ( int ) ; int a ; } ; And the task is "Inside the code provide declarations for : pointer to int variable of class X pointer to function void(int) defined inside class X pointer to double variable of class X" Ok so pointer to int a will be just int *x = &a, right ? If there is no double...

Why does std::cout convert volatile pointers to bool?

If you try to cout a pointer to a volatile type, even a volatile char pointer where you would normally expect cout to print the string, you will instead simply get '1' (assuming the pointer is not null I think). I assume output stream operator<< is template specialized for volatile pointers, but my question is, why? What use case motivat...

Loop with pointer arithmetic refuse to stay within boundary in C. Gives me segfault.

Hi have made this function which is made to replicate an error that I can't get past. It looks like this: void enumerate(double *c, int size){ while(c < &c[size]){ printf("%lf\n", *c); c++; } } I have added some printf's in there and it gives me: Adressof c: 0x100100080, Adressof c + size: 0x1001000a8...

Search string in file (C)

So my code isn't working... test.c:27: warning: passing argument 1 of ‘search’ from incompatible pointer type which is the fgets line. My code opens a file, reads the file line by line, and I'm trying to create a "search" function that will return a value that indicates whether that string is found on that line of the file. My ultim...

Modifying a const through a non-const pointer

I'm a bit confused what happened in the following code: const int e = 2; int* w = ( int* ) // (1) cast to remove const-ness *w = 5; // (2) cout // (3) outputs 5 cout // (4) outputs 2 cout // (5) w points to the address of e cout In (1), w points to the address of e. In...