Pointers are variables themselves, so a pointer that points to another pointer is a pointer to pointer. A pointer to pointer is sometimes mistakenly referred to as "double pointer".
Questions tagged [pointer-to-pointer]
234 questions
0
votes
2 answers
What does this double pointer do in c programming?
#include
#define LENGTH 3
char *words[LENGTH];
int main( int argc, char *argv[] )
{
char *pc; // a pointer to a character
char **ppc; // a pointer to a pointer character
printf( "\n------------Multiple…
ciphermute
- 401
- 1
- 4
- 4
0
votes
2 answers
How to deconstruct complex C/C++ statements/declarations?
Take the following snippet as an example.
char* const (*(* const bar)[5])(int)
Cannot seem to make sense of it or more so, cannot identify the initial point from where to begin making sense of it.
deft artisan
- 15
- 3
0
votes
1 answer
Question about argument in a function as a pointer to a pointer
I am reading the book "C Programming: A Modern Approach" by KN King, where in chapter 17.5 on page 432 they define a function for deleting a node from a singly linked list:
The following function, delete_from_list, uses the strategy that we've just…
Fary
- 77
- 4
0
votes
1 answer
Failed to manipulate the string passed as pointer to pointer inside the function
I am creating a removeNonAlphaCharacters function trying to remove all non alphabetic characters using C.
I could remove all non-alphabetic characters inside the function, but I can not pass the modified string back the original string, which means…
rui wang
- 3
- 2
0
votes
1 answer
Why does malloc(0) in C not produce an error when working with char pointer pointers
I'm trying to write a simple split function in c, where you supply a string and a char to split on, and it returns a list of split-strings:
#include
#include
#include
char ** split(char * tosplit, char delim){
…
Sam van Kesteren
- 9
- 2
0
votes
1 answer
Getting Null iterate through to next element of array using pointers
#import
#import
typedef struct Video {
char *name;
int unique_views;
} Video;
typedef struct Viewer {
char *username;
Video *watched_videos;
int watched_videos_size;
} Viewer;
int count_views(Viewer…
Anshal Antony
- 3
- 1
0
votes
3 answers
How to understand secondary pointer?
i want to ask a question about pointer:
void fun(const char** a) {...}
1.
const char* b = nullptr;
fun(&b);
2.
const char** b = nullptr;
fun(b);
why use 1 but not 2?
1 is good, 2 donnot work
Yeatsflee
- 23
- 1
0
votes
1 answer
struct using a pointer, ... in something not a struct or union
I defined a structure called coordonnees declared as a pointer, I want to append values to the pointer a_visiter but it's not working. How can I fix that?
Here is the struct code:
typedef struct couple
{
int ligne;
int…
Elas
- 21
- 2
0
votes
0 answers
Pointer to Pointer Memory-address
about pointers in C++
why we use ** in pointer to pointer
I just want to know the reason
why we use ** in pointer to pointer
what is the main reason of using double indirections ?what is the logic behind it?
or it is just a syntax?
are there any…
Mpujara
- 1
0
votes
1 answer
how to dynamically allocate a 2d array with the help of a function in C
void alloc_matrix(int ***mat, int *m, int *n) {
mat = (int **)malloc(*m * sizeof(int *));
for(int i = 0; i < *m; i++)
mat[i] = (int *)malloc(*n * sizeof(int));
for(int i = 0; i < *m; i++)
for(int j = 0; j < *n; j++)
…
MXF
- 1
- 1
0
votes
1 answer
How to update field of a pointer to a struct in C?
Im trying to update a field of a struct that's a pointer like so:
typedef struct Data *STRUCT_POINTER;
typedef struct Data
{
int element;
STRUCT_POINTER next;
} STRUCT_NODE;
void manipulate(STRUCT_POINTER *data ) {
data->element =…
Cloyd Abad
- 617
- 8
- 16
0
votes
1 answer
inserting node at the beginning of a circular linked list using void function
I m trying to insert a node at the beginning of a circular linked list using a void function.
When i pass pointer to pointer head in the function because i have to change the head itself, it is throwing me some error on line 24 where i marked it…
Neilson Programmer
- 25
- 6
0
votes
2 answers
G++ responds differently to const int** and const int* as function parameters
I was writing a C++ function that takes int** as input and the function itself does not modify the data (i.e. matrix elements). So I decided to make the argument a const int** type (Is that an acceptable practice?). A sample code is like this:
void…
oaaij-gnahz
- 3
- 2
0
votes
2 answers
Incompatible pointer type pointer to array and double pointer to array
So i am new to programming and i have this program that i have to write, it has an array of integers and i have to pass it to a function with a pointer and then with a double pointer.
After i wrote the code i had this error that i couldn't find a…
Cromocon
- 13
- 2
0
votes
0 answers
Assigning a pointer to "member function pointer" to a pointer to "void"
#include
struct Adder {
int a, b;
int operator()() { // member function.
return a+b;
}
};
int main() {
using MemFuncPtr = int(Adder::*)() ;
alignas(64) char buf[64]; // closure object (size <= 64) is…
tmal
- 47
- 6