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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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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0answers
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I have a class that is derived from a QList object. I have used for loops, I keep getting the error that list is not declared in the scope [migrated]

I have a class that is derived from a QList object. I have used for loops, I keep getting the error that list is not declared in the scope #include "AssetList.h" #include "Asset.h" ...
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3answers
293 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
115 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
143 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 ...
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3answers
319 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
444 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
184 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
192 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
523 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
292 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
139 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
664 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
1k 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
174 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
222 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 ...
6
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1answer
210 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 ...
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1answer
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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; ...
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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 ...
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5answers
3k 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
449 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 ...
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4answers
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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 ...
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5answers
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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
555 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++ ...
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2answers
309 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, ...
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4answers
605 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 ...
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3answers
985 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
802 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 ...
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3answers
2k 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); }; // ...
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4answers
972 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 ...
3
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2answers
374 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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2answers
436 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 ...
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2answers
401 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 ...
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5answers
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What is the point of dynamic allocation in C++?

I really have never understood it at all. I can do it, but I just don't get why I would want to. For instance, I was programming a game yesterday, and I set up an array of pointers to dynamically ...
2
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3answers
593 views

introducing pointers to a large software project

I have a fairly large software project written in c++. In there, there is a class foo which represents a structure (by which i don't mean the programmers struct) in which foo-objects can be part of a ...
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6answers
794 views

why are both index[array] and array[index] valid in C?

For example consider: int index = 3; int array[4] = {0, 1, 2, 3}; then both index[array] and array[index] are valid expressions, much like *(index + array) and *(array + index). In C arrays why is ...
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9answers
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Pointers in C vs No pointers in PHP

Both languages have the same syntax. Why does C have the weird * character that denotes pointers (which is some kind of memory address of the variable contents?), when PHP doesn't have it and you can ...
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3answers
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How is a Java reference different from a C pointer?

C has pointers and Java has what is called references. They have some things in common in the sense that they all point to something. I know that pointers in C store the addresses they point to. Do ...
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4answers
283 views

What are good strategies in C for dealing with pointer errors of this type?

In C, I often come across errors with code like this prio_queue->head[index] = newEntry; Yields a " "Cannot assign Entry** to Entry* " How do you prevent/debug errors of this type, in general? ...
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4answers
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What is the difference between a pointer pointing to 0x0 location and a pointer set to NULL?

Is a pointer pointing to 0x0000 the same as a pointer set to NULL? If NULL value is defined in the C language, then what location does it physically translate to? Is it the same as 0x0000. Where can I ...
12
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5answers
901 views

How is precedence determined in C pointers?

I've come across two pointer declarations that I'm having trouble understanding. My understanding of precedence rules goes something like this: Operator Precedence ...
4
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6answers
1k views

Is it best to minimize using pointers in C?

I think most people would agree that pointers are a major source of bugs in C programs (if not the greatest source of bugs). Other languages drop pointers entirely for this reason. When working in C, ...
2
votes
5answers
1k views

What is the purpose of arrays in C, when pointers could have done the job?

Arrays and pointers are not the same thing in C, although they are related and can be used similarly. So far we all agree. However, I don't see why arrays were included in C, when pointers could have ...
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5answers
1k views

Who invented pointers?

Pretty simple question, but something I haven't been able to find out. Who was the first person to describe the idea of a pointer? The abstract concept itself?
53
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17answers
5k views

What programming problems are best solved by using pointers?

Well, I basically understand how to use pointers, but not how best to use them in order to do better programming. What are good projects or problems to resolve involving the use of pointers so I can ...
4
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5answers
2k views

Do I need to understand pointers to use C++?

Well, I love C++, I have been using it for a while: I like all the libraries (Allegro, SDL, QT, Ogre, etc.), but I have a problem: I don't understand pointers. Do I really need them ? I just program ...
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5answers
1k views

function pointers are so complex to me

I found this code sample in this answer by Armen Tsirunyan. class MyClass { public: typedef void (*funcPtr)(int, int); MyClass(funcPtr whatToCall) { callme = whatToCall; } ...
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15answers
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Will real world applications ever need a 128-bit flat address space?

This is a bit "one megabyte should be enough for anyone", but... A 64-bit flat address space allows up to 4.3ish billion times more space than a 32-bit address space. That's 17,179,869,184 GiB. ...
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2answers
229 views

Is a small demo a good idea for an interview?

Unfortunately most of my work is internal -- I was toying with the idea of a small web demo to give the company better insight. What do you think?