Show 2 more comments. Active Oldest Votes. Reviewing the basic terminology It's usually good enough - unless you're programming assembly - to envisage a pointer containing a numeric memory address, with 1 referring to the second byte in the process's memory, 2 the third, 3 the fourth and so on What happened to 0 and the first byte?
Well, we'll get to that later - see null pointers below. For a more accurate definition of what pointers store, and how memory and addresses relate, see "More about memory addresses, and why you probably don't need to know" at the end of this answer.
A pointer scenario Consider in C, given a pointer such as p below Losing and leaking addresses Often a pointer may be the only indication of where some data or buffer exists in memory. More about memory addresses, and why you probably don't need to know More strictly, initialised pointers store a bit-pattern identifying either NULL or a often virtual memory address.
Improve this answer. Pacerier: from 6. Honey: the value hex is too big to encode in a single byte 8 bits of memory: you can only store unsigned numbers from 0 to in one byte.
So, you just can't store hex at "just" the address Instead, a bit system would use 32 bits - which is four bytes - with addresses from to A bit system would use 64 bits - 8 bytes - from to Either way, the base address of p is just if you had another pointer to p it would have to store in its four or eight bytes.
Hope that helps! TonyDelroy: If a union u contains an array arr , both gcc and clang will recognize that the lvalue u. I'm not sure whether the authors of those compilers think that the latter invokes UB, or that the former invokes UB but they should process it usefully anyway, but they clearly view the two expressions as different.
TonyDelroy: What's needed for safety and optimization isn't so much a "bit cast" operator, but rather a "restricted pointer" type which during its lifetime requires that all parts of an object that are accessed using a restricted pointer be accessed exclusively through it, and whose constructor could take a pointer of any type and cause accesses made through the restricted pointer to be treated as accesses to the original type. Most code that needs to use type punning would be amenable to such a construct, and it would allow many useful optimizations that would go beyond TBAA.
Show 15 more comments. So, dereferencing gives this value. This is an indirect way to access a. Migol 7, 8 8 gold badges 45 45 silver badges 69 69 bronze badges. Mahesh Mahesh 33k 17 17 gold badges 82 82 silver badges bronze badges. A pointer doesn't point to a value , it points to an object. KeithThompson A pointer does not point to an object, it points to a memory address, where an object maybe a primitive is located.
A pointer value is an address. An object, by definition, is a "region of data storage in the execution environment, the contents of which can represent values".
And what do you mean by "primitive"? The C standard doesn't use that term. KeithThompson I was barely pointing out, that you did not actually add value to the answer, you were only nitpicking on terminology and did that wrong also. The pointer value surely is an address, that's how it "points" to a memory address.
Show 6 more comments. Add a comment. Peter Mortensen 29k 21 21 gold badges 97 97 silver badges bronze badges. Fahad Naeem Fahad Naeem 6 6 silver badges 14 14 bronze badges. Code and explanation from Pointer Basics : The dereference operation starts at the pointer and follows its arrow over to access its pointee. You actually have to allocate memory for where x is supposed to point at. Your example has undefined behavior. Have you tried? I did. The Overflow Blog. Podcast Explaining the semiconductor shortage, and how it might end.
Does ES6 make JavaScript frameworks obsolete? Featured on Meta. Now live: A fully responsive profile. Visit chat. Linked 1. See more linked questions. Related Hot Network Questions. To know something is to be aware of it as a fact or truth: He knows the basic facts of the subject.
I know that he agrees with me. To comprehend is to know something thoroughly and to perceive its relationships to certain other ideas, facts, etc. To understand is to be fully aware not only of the meaning of something but also of its implications: I could comprehend all he said, but did not understand that he was joking.
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