CODEWITHSUNDEEP
ccharbitwise-operators
Torhan Bartel
Torhan Bartel

Reputation: 560

Bitoperators in C on char*

Is there a way to to something like:

char* a = "Hello";
char* b = NULL;
char* c = a | b;

Result should be c = "Hello";

Seems like it does not work with Char*, but is there a way to do something like that?

Upvotes: 0

Views: 95

Answers (3)

igordsm
igordsm

Reputation: 464

It is possible using ternary operators. The code below sets c to b if a == NULL and sets c to a otherwise.

char *c = (a == NULL)? b : a;

Now a clarification on bitwise operators: | and & work on the bits of the operands. Suppose we have two variables, a = 10000001 (128) and b = 10000010 (129). It does not matter the type of a and b, only the bit representation of their values.

a | b = 10000011, that is, it takes the bitwise OR between the bits of a and b;

a & b = 10000000, that is, it takes the bitwise AND between the bits of a and b;

These operators make sense when you are working directly with the bits of the value of your variables. In C, the value of a pointer is the address of a chunk of memory, not the contents of its chunk. Applying a bitwise operation on pointers means applying a bitwise operation on the addresses that they hold. The result of this operation can point to almost anywhere on the memory and using this pointer will probably get you a Segmentation Fault (or at least junk data).

Upvotes: 1

KamikazeCZ
KamikazeCZ

Reputation: 724

This is nonsense not only because bitwise operators on pointers would have very... interesting... results, but mainly because NULL is not guaranteed to be represented by 0.

Upvotes: 1

Barmar
Barmar

Reputation: 781716

The following will set c to a if it's not null, otherwise set it to b:

char *c = a ? a : b;

This is called the ternary operator.

Upvotes: 0

Related Questions