Jul 24, 2016 · On error, (void *) -1 is returned, and errno is set to ENOMEM. Now, What's the significance of (void *) -1? What is the exact memory address it points to? (if it does at all) How is it guaranteed that (void *) -1 is not a valid address that can be returned by sbrk() on success?

Jul 10, 2019 · The so-called safe bool idiom is a misnomer, though -- dirty hack would be better suited. It is by no means safe, or expresses intent well. A bool communicates: "this is a yes or no value" whereas a void* communicates "I am a pointer, please dereference me". Which, for (void*)0 or (void*)1usually isn't such a brilliant idea. The fact that it ...

Jul 24, 2012 · A void * can be converted to any other pointer type without an explicit cast. You cannot dereference a void * or do pointer arithmetic with it; you must convert it to a pointer to a complete data type first. void * is often used in places where you

Nov 9, 2012 · However, it is not necessary for (void *) -1 not to be a valid address in order for shmat to work. It is merely necessary that a successful call to shmat never returns (void *) -1 and that (void *) -1 be supported by the compiler for purposes of testing the return value from shmat. If these two conditions are met, then a program can always ...

Mar 20, 2009 · ¹ In ECMAScript 5 and later, the global variable undefined is guaranteed to be undefined (ECMA-262 5th Ed., § 15.1.1.3), though it is still possible to have a variable inside an inner scope be named undefined.

Jun 25, 2009 · Here the meaning of void is different from other meanings of void: universal type vs. no type. In casts such as (void) new Foo(this) to signify that the return value is deliberately thrown away. Here the keyword usage also matches its meaning in English. Cases 1 and 2 were already covered by @Gerald but case 3 has not been addressed yet.

Oct 15, 1975 · I have made a typedef for a function pointer that takes in an integer and returns a void *: typedef void* (*fp)(int index); I then made a struct that contains a fp and another struct of the same t...

gcc has an extension that treats sizeof (void) as 1. gcc is not a conforming C compiler by default, so in its default mode it doesn't warn about sizeof (void). Extensions like this are permitted even for fully conforming C compilers, but the diagnostic is still required.

Aug 30, 2021 · On top of that, Douglas Crockford doesn't like void, so jslint will complain about it. Basically, since void is an operator, and not a value, it's confusing as hell, and spawns many questions such as this one. Better to avoid it altogether. haha. –

void(): This operator allows inserting expressions that produce side effects into places where an expression that evaluates to undefined is desired. The void operator is often used merely to obtain the undefined primitive value, usually using "void(0)" (which is equivalent to "void 0"). In these cases, the global variable undefined can be used ...