A pointer is a data type whose value refers directly to (or "points to") another value stored elsewhere in the computer memory using its address.

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Why are the raw pointer values being overwritten/falling out of scope [migrated]

I have a C++11 function making calls against a legacy C function. I thought it would be good to create worker threads(using std::thread that will then pass variables to the C function. However, it ...
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3 views

updating multidimensional pointers for radix buckets [migrated]

First post on Stackexchange, so - hi everyone. I'll give a short background to my situation: Our professor isn't really helpful and doesn't quite know his things well, especially when it comes to ...
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2answers
188 views

Autoreleasing objects in Reference Counting Systems

I'm experimenting a bit in C and I'm trying to implement my own Reference Counting System. I've mainly worked with Objective-C in the past but AFAIK autoreleasing objects is something that is unique ...
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0answers
41 views

why pointer variable not showing 100 digits? [migrated]

aim: i had a requirement for accuracy i need 100 digits to be displayed try 1: first i had used integer variable then it displayed only 10 digits try 2: with the help of my friend i used pointers ...
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2answers
133 views

C Linked List Implementation Pointer vs. Pointer-to-Pointer Consistency

To get some practice in C, I'm writing some basic functions for operating on a linked list of ints. I started out with functions that accepted as a "list" a pointer to the head node. Now, I find ...
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3answers
316 views

C++ Chess board design and smart pointers [closed]

I wrote a Chess engine in Java and I am porting it over to C++. I am new to C++. The idea: I have a Board object which holds a 2-dimensionnal array of Piece objects. Queen, Rook, Bishop, etc are ...
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4answers
407 views

How to work around Java's lack of pointers to pointers when working with linked data structures? [closed]

I've learned from a textbook how to implement binary search trees recursively in Java, and am working on implementing them nonrecursively. I've found a simple and elegant way to implement an insert ...
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4answers
197 views

Storing a pointer to an argument passed by (non-const) reference

When designing an interface for passing objects which are meant to be stored for later use and which should not be 'null', I am always a bit uncertain if the argument should be passed by reference or ...
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6answers
424 views

What are memory addresses? [closed]

I have more or less 0 knowledge in low-level topics, so forgive my possible ignorance. I know that in languages such as C, pointers hold 'memory addresses', i.e. strings (or binary data?) written in ...
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1answer
88 views

In C++11 can Auto be used to get around mis-casting of void * parameters in functions?

If I have a generic function that takes a void* as a parameter, can Auto in C++11 help stop any bad casting of that parameter? For instance, we may have an event system that sends events and a ...
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3answers
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Why Increment Pointers?

I just recently started learning C++, and as most people (according to what I have been reading) I'm struggling with pointers. Not in the traditional sense, I understand what they are, and why they ...
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2answers
192 views

Assigning strings to pointer in C Language

I am a new learner of C language, my question is about pointers. As far i learned and searched pointers can only store addresses of other variables, but cannot store the actual values(like integers or ...
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4answers
1k views

Pointer indexing

I am currently reading a book titled "Numerical Recipes in C". In this book, the author details how certain algorithms inherently work better if we had indices starting with 1 (I don't entirely follow ...
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2answers
149 views

Can a version of Python's shelve module that knows when its entries have been modified be written in any programming language?

shelve is a Python module that makes it easy to persist a Python dictionary to disk (under the right conditions). The documentation for shelve gives this example to demonstrate one of the pitfalls of ...
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3answers
328 views

usage of double pointers and n pointers?

I am familiar with basic C pointers. Just wanted to ask what is the actual use of double pointers or for that matter n pointer? #include<stdio.h> int main() { int n = 10 , *ptr , **ptr_ptr ; ...
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0answers
32 views

Binary Tree Address Conflictions

I wrote a post on a similar topic yesterday about my destructor for my Huffman tree class program. I have since isolated an issue with how my tree is being built that has me pretty baffled at the ...
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2answers
254 views

Usage of raw pointers

So from the top-voted answer to this question, it appears that using raw pointers for storage isn't frowned upon so much. However, then what is the point of a std::weak_ptr? I thought that storage was ...
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5answers
137 views

What conclusion to be drawn from no difference in generated assembly from 2 rather different programs?

I might not have had a counterexample when I got the reply "A pointer is just an address, what's the difficulty?" but I didn't really buy such a simple explanation and at assembly code it's not ...
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3answers
510 views

How to teach pointers to beginners in C? [closed]

I'll hold a little presentation about C-Pointers in a small group of people with beginners programming skills, with no CS background. Just people who would like to learn something about coding and ...
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2answers
160 views

Difference between a pointer and a reference? [duplicate]

In Java and other high-level languages, a reference leads to an object. In C++, as far as I know, a pointer can also lead to an object. So what's the difference between a reference leading to an ...
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3answers
195 views

ANSI C pointers corrupted values

I am working on ANSI C and having some issues with the pointers. That is that after a point in my program the pointer's values change without me interfering, is something like overwriting them. I ...
2
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3answers
341 views

Why are pointers to literals not possible?

Reference to a literal is possible only if the reference is declared as constant. But why is a pointer to a const object not possible in case of literals? i.e. int const& ref = 5;// But why ...
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4answers
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Why do C++ and Java both use the notion of “reference” but not in the same sense?

In C++ a reference argument to a function allows the function to make the reference refer to something else: int replacement = 23; void changeNumberReference(int& reference) { reference = ...
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3answers
468 views

How do you read this line of code?

Forgive me for my poor English, me and my friend were doing school homework, suddenly he asked me to read this line of code ptr = &array[1][1][1] (ptr is a pointer to an integer). He said ...
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2answers
243 views

Is it better to use an external variable or to pass around a pointer?

While writing in C, I have always wondered about when is the best time to use an external variable. I generally prefer to pass a pointer into a method. Is there a correct time to use an external ...
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3answers
218 views

adding array pointer in c

I am having problems understanding how this equation works in c: char *sum(char *a, int b) { return &a[b]; } printf("%d", sum(5, 4)); I understand how arrays work, and I understand how to ...
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2answers
1k views

Storing a pass-by-reference parameter as a pointer - Bad practice?

I recently came across the following pattern in an API I've been forced to use: class SomeObject { public: // Constructor. SomeObject(bool copy = false); // Set a value. void ...
3
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1answer
396 views

What are the real life use cases for tagged pointers? [closed]

What are the real life use cases for tagged pointers? This is mostly coming from reading about small 64-bit systems and possible uses of 64-bit word pointers. To my understanding tagged pointers are ...
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1answer
306 views

Pointer access and cache coherency

To my understanding, when you access a variable, that variable and the surrounding area of memory is put into the L1 cache. If I'm wrong here, please tell me. Now my question is, say I have an array ...
3
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5answers
744 views

What is the definition of pointer? [duplicate]

Conceptually a "pointer" is just something that "points" to something else;Is this definition is sufficient to tell exactly what a pointer is in programing languages? Does it need to have any other ...
2
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2answers
4k views

Do pointers really exist in Java? [duplicate]

I read quite a few resources on the internet and now I am quite confused about the existence of pointers in Java. Some claim that there are pointers and some claim that there is no such concept. So ...
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3answers
223 views

Garbage collectors and pointers/ reference

I am a little confused on both pointers and reference. From my understanding pointers are addresses in memory. If I pass a variable using pointers and reference to a function, any manipulations of ...
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1answer
301 views

Is there a proper way to allow access to private list by reference?

I'm trying to provide a by-reference getter to a list of objects in a class. My setup looks something roughly like this: class c_Container { public: c_Item* Get(int uid); private: c_Item ...
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1answer
217 views

Hardware that accelerates pointer dereferencing?

Most modern languages make a heavy use of pointers / references: a typical OOP language uses VMT lookups, a typical functional language builds key data structures out of pointers, etc. Even typical C ...
6
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1answer
2k views

Is this a valid example of a dangling pointer?

The book "Data Structures in C" (Horowitz and Sahni) suggests that in the following code the pointer pf is behaving as a dangling reference: float f,*pf; pf=(float*) malloc(sizeof(float)); *pf=2.6; ...
4
votes
4answers
2k views

Was C designed to facilitate Object-Oriented programming?

I am trying to broaden my understanding of the history and development of object-oriented programming, and I am curious to find out if C was designed to facilitate Object-Oriented programming? (like ...
6
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5answers
6k views

Is there any difference between pointers and references? [duplicate]

References and pointers do the same thing as I know. Is there any difference between them? If there is no difference, why we call them reference not pointer?
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1answer
994 views

Converting 'char*' to 'char'. Am I passing this array correctly? [closed]

So my CS professor gave the whole class a simple assignment. "Write a recursive function that will swap the order of a section in an array of chars." I thought to myself, "Easy. I'll finish this up in ...
11
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4answers
6k views

C++ why & how are virtual functions slower?

Can anyone explain in detail, how exactly the virtual table works & what pointers are associated when virtual functions are called. If they are actually slower, can you show the time that the ...
6
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5answers
2k views

When and why would we use immutable pointers?

In Java, the String object is both immutable and also a pointer (aka reference type). I'm sure there are other types/objects which are both immutable and a pointer as well and that this extends ...
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2answers
891 views

C++ Typecasting VS performance

Let's say we're designing a video game. We have some sprites on the map and we want to call some method of the particular sprite at some particular position. We are using one broadly-known C++ ...
3
votes
2answers
314 views

What happens when using address before it's allocated?

The very simple piece of C++ code below is incorrect, it's easy to see why and tools like Valgrind will tell you. In running several C++ codes containing this kind of error, I noticed that each time, ...
5
votes
4answers
619 views

What's a good way to explain the need for pointing to a pointer?

Understanding what a pointer (an address) is, is fairly easy and an eleven-year old can understand it. But how do we express why we have a need for a pointer to a pointer? what is a very pedagogical ...
2
votes
3answers
1k views

C++ Pointers: Number of levels of Indirection

In a C++ program that doesn't contain legacy C code, is there a guideline regarding the maximum number of levels of indirection that should be used in the source code? I know that in C (as opposed to ...
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4answers
941 views

C simple arrays and pointers question

So here's the confusion, let's say I declare an array of characters char name[3] = "Sam"; and then I declare another array but this time using pointers char * name = "Sam"; What's the ...
2
votes
3answers
3k views

Functions returning pointers

C++ noob here. I have a very basic question about a construct I found in the C++ book I am reading. // class declaration class CStr { char sData[256]; public: char* get(void); }; // ...
5
votes
5answers
2k views

What's so bad about pointers in C++?

To continue the discussion in Why are pointers not recommended when coding with C++ Suppose you have a class that encapsulates objects which need some initialisation to be valid - like a network ...
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votes
2answers
533 views

Explanation of satellite data from a programmers perspective

I have started reading Part 2 of Introduction to Algorithms and in the section The structure of the data the author/authors says in the context of sorting a sequence of numbers: In practice, the ...
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votes
2answers
630 views

what will be the Output of the following code written in “ C”?

#include<stdio.h> void main() { char ***p="hello"; printf("%c",++*p++); } I haven't understand the concept of (*) indirection uses here three times. When i compiled this program then the ...
2
votes
2answers
495 views

The best way to have a pointer to several methods - critique requested

I'm starting with a short introduction of what I know from the C language: a pointer is a type that stores an adress or a NULL the * operator reads the left value of the variable on its right and ...