How to make a pointer increment by 1 byte, not 1 unit

Question

I have a structure tcp_option_t, which is N bytes. If I have a pointer tcp_option_t* opt, and I want it to be incremented by 1, I can't use opt++ or ++opt as this will increment by sizeof(tcp_option_t), which is N.

I want to move this pointer by 1 byte only. My current solution is

opt = (tcp_option_t *)((char*)opt+1);

but it is a bit troublesome. Are there any better ways?

You really don't want to do that...or, perhaps, why on earth do you think you want to do that (because you really don't want to do that!)? — Jonathan Leffler, May 16 '13 at 02:47
No, that's exactly the right way to do it. But why would you want to? — Lee Daniel Crocker, May 16 '13 at 04:17

score 18 · Accepted Answer · answered May 16 '13 at 03:51

18

I'd suggest you to create a pointer of char and use it to transverse your struct.

char *ptr = (char*) opt;
++ptr; // will increment by one byte

when you need to restore your struct again, from ptr, just do the usual cast:

opt = (tcp_option_t *) ptr;

answered May 16 '13 at 03:51

Amadeus

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How to make a pointer increment by 1 byte, not 1 unit

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