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

c pointers increment
misteryes picture misteryes · May 16, 2013 · Viewed 17.8k times · Source

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?

Answer

Amadeus picture Amadeus · May 16, 2013

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;

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