null-pointer

What is the normal behavior in Objective-C if you call a method on an object (pointer) that is nil (maybe because someone forgot to initialize it)? Shouldn't it generate some kind of an error (segmentation fault, null pointer exception...)? If this is normal behavior, is there a way of changing this behavior (by configuring the compiler) so that the program raises some kind of error / exception at runtime? To make it more clear what I am talking about, here's an example. Having this class: @interface Person : NSObject { NSString *name; } @property (nonatomic, retain) NSString *name; - (void

So I was going through some interview questions and I came across one about void and null pointers , which claims: a pointer with no return type is called a null pointer. It may be any kind of datatype. This confused me thoroughly! It seems void and null could be used interchangeably according to this question, and I don't believe that to be correct. I assumed void to be a return type and null to be a value. But I am just a code-rookie and am not sure I am right. Please express your views as to what a null pointer is and a void pointer is. I am not looking for difference between null and void.

First of all, I've seen this question about C99 and the accepted answer references operand is not evaluated wording in the C99 Standard draft. I'm not sure this answer applies to C++03. There's also this question about C++ that has an accepted answer citing similar wording and also In some contexts, unevaluated operands appear. An unevaluated operand is not evaluated. wording. I have this code: int* ptr = 0; void* buffer = malloc( 10 * sizeof( *ptr ) ); The question is - is there a null pointer dereference (and so UB) inside sizeof() ? C++03 5.3.3/1 says The sizeof operator yields the number

Is it safe to check a pointer to not being NULL by writing simply if(pointer) or do I have to use if(pointer != NULL) ? You can; the null pointer is implicitly converted into boolean false while non-null pointers are converted into true. From the C++11 standard, section on Boolean Conversions: A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool . A zero value, null pointer value, or null member pointer value is converted to false ; any other value is converted to true . A prvalue of type std::nullptr_t can be converted to

This question already has an answer here: Why doesn't my program seg fault when I dereference a NULL pointer inside of malloc? 4 answers I've come across a snippet of code that to me should crash with a segmentation fault , and yet it works without a hitch. The code in question plus relevant data structure is as follows (with associated comment found right above): typedef struct { double length; unsigned char nPlaced; unsigned char path[0]; } RouteDefinition* Alloc_RouteDefinition() { // NB: The +nBags*sizeof.. trick "expands" the path[0] array in RouteDefinition // to the path[nBags] array