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# What it entails to declare and initialize a pointer in this way: int (*p)[n]

By : Антон Попов
Date : September 23 2020, 08:00 AM
I wish this helpful for you I'm learning about pointers arithmetic and there's an example about processing the columns of a 2D array exploiting pointers, precisely. In order to do that, the code shows a new-to-me declaration of a pointer, here's the snippet: , A syntax like
code :
`````` int (*p)[NUM_COLS];
``````
`````` int arr[NUM_COLS] = {0};
p = &arr;
``````

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## Declare and initialize pointer concisely (i. e. pointer to int)

By : Vincenzo Sicurella
Date : March 29 2020, 07:55 AM
Does that help String literals are a corner case : they trigger the creation of the literal in static memory, and its access as a char array. Note that the following doesn't compile, despite 42 being an int literal, because it is not implicitly allocated :
code :
``````int *p = &42;
``````
``````int i = 42;
int *p = &i;
``````
``````int * i;
*i = 42;
``````
``````int *i = malloc(sizeof *i);
``````
``````int i = 42, *p = &i;
``````
``````int *p = &(int){42};
``````
``````int i[] = {42};
``````

## Why can't I initialize and declare pointer to pointer to NULL in C?

By : Karthik Kumar
Date : March 29 2020, 07:55 AM
it should still fix some issue I wrote a C program. Some part of the code which is inside a function looks like this: , You have two examples of dereferencing a pointer.
code :
``````struct node **head = NULL;
``````
``````struct node **head;
``````
``````struct node **head = malloc(sizeof(*head)*SOME_COUNT);
``````

## C, Why can't I declare pointer and initialize it?

By : María Maestre Barrio
Date : March 29 2020, 07:55 AM
I wish did fix the issue. Well, I have the following code: ,
warning: assignment makes integer from pointer without a cast
code :
``````*str = *envp++;
``````
``````str = *envp++;
``````

## how to declare array pointer first, and initialize later in java

By : user1961300
Date : March 29 2020, 07:55 AM
To fix the issue you can do When you are not sure of the size of array you need you can use java.util.ArrayList instead of array. ArrayList internally consists of an array and a logic for resizing it based on need. Please refer the below code for your reference :
code :
``````import java.util.*;

public static void main(String[] args){
Scanner sc = new Scanner(System.in);

List<Integer> arrList = new ArrayList<>(); // No need to specify size
int i = 0;
while(sc.hasNextInt()){
arrList.add(sc.nextInt()); // it will take care of resizing the array internally based on the inputs
}
}
``````

## Declare a pointer in a class but initialize in another thread

By : dvnu
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , I declare a pointer called download_webm in the main class and i want to initialize it in my thread constructor but every time I try to do that the program crash when I try to connect download WebM and player.
code :
``````MyThread::MyThread(DownloadWebm* we)
``````
``````webm = &we;
``````
``````MyThread *DownloadWebm_Thread = new  MyThread(download_webm);
``````
``````MyThread *DownloadWebm_Thread = new  MyThread(&download_webm);
``````
``````MyThread::MyThread(DownloadWebm *&we)
``````