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#define NULL ((void *)0) /* defined in <stddef.h> */
const char *mynullvar = NULL;
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What is NULL array in C Language?
There is no "NULL array" as such, you may take a pointer to an array and set it to NULL (binary 0) e.g. int* foo; // Declare a pointer foo = malloc( 40 * sizeof(int)); //Allocate an array of 40 integers pointed to by "foo" foo = NULL; //Set the pointer to NULL, if you're using a garbage collector this should trigger an automatic free() of the memory allocated to the array. If you are NOT using a garbage collector (which is more common in C) this line is a memory leak.
Java null pointer exceptions?
A null pointer exception in java comes when you are trying to perform any action on an object that isnt initialized/has a value i.e., is a NULL Value Ex: private String s; //declare a string if(s.equals("test")){ //do something.. } You will get a null pointer in the if condition because you are checking a value that is null which is not allowed..
What is the use of null pointer?
Pointer is a variable that stores address of a variable . A NULL Pointer a pointer that doesn't point to anything, it is a literal zero .Some people ,notably C++ programmers, prefer to use 0 rather than NULL.
How do you declare pointer in c?
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Why you get null pointer assignment error occurs in c?
You haven't assigned the pointer yet, so it's initialized as NULL, or you're trying to assign NULL to the value of the pointer. You have to check if the value is NULL before you use it, or you'll end up with errors just like this.
What is null object in c plus plus?
a pointer that is not pointing to anything
What is the difference between a null pointer and a null macro?
Using a NULL macro to make C portableI'll assume that you're asking your question for C type language programming. A NULL pointer is a pointer that's guarnteed to point to nothing. This may be 0 in a UNIX/Linux system or some other address in another system. Using the NULL macro to set/initialize your pointers will make your programs more portable among systems than using something like the 0.#include char *c = 0; // initialize to NULL--not portablechar *p = NULL; // initialize to NULL as defined in stdio is portableAddendumThe code:char *c = 0;actually is portable because the compiler converts 0's used in a pointer context (cast to a pointer) to the machine's representation of a NULL pointer, which may or may not be all 0 bits. The NULL macro itself might be defined as something like 0 or (void *)0, and both definitions are portable. As a corollary, the following code is also portable:if (!c) {// do something}because it is equivalent to:if (c != 0) {// do something}and the 0 above is converted to a NULL pointer because it is being compared with a pointer.
What is null point in C programming?
I'm going to go out on a limp here, and guess you mean "Null Pointer." Well, it's a pointer to nothing. For most systems, it's 0, but rather use NULL instead.
How do you declare a pointer to a character string in c?
char *ptr;
How do you declare a pointer variable in c?
int* pint; // instantiate a pointer to an int. float* pflt; // instantiate a pointer to a float.
What is a null macro what is the difference between a null pointer and a null macro?
NULL Macro is simply what is defined as 0 in a macro provided by the libraryNull pointer is a pointer which has 0 or NULL value stored and points to nowhwere still it points to 0x00 i.e. the first memory location of the OSNull pointer != Uninitialized pointer because an uninitialised pointer can point anywhere in the memory location ...but a NULL pointer surely points to no where(but still behind the scene we can say that it only points to 0x00). Never we can retrive a Null pointer location using th"&" operator..neither will malloc/calloc return NULL IF THERE IS SPACE IN THE MEMORY. NULL pointer is unique !!nishantnitb@aol.com
Java does not support pointers then what is null pointer exception?
A null pointer exception is thrown when you are trying to manipulate an object that is null. It is just the name and does not have any relevance to the pointers as in C Example: ArrayList lst = null; Object obj = lst.get(0); In the first line we have declared an array list. Without initializing it we have tried to access the element in the 0th position. This would cause a null pointer exception.
