Le nonidi 9 frimaire, an CCXXIV, Ganesh Ajjanagadde a écrit : > >> end = p + strlen(p) - 1;
> Don't know what you are referring to here, but dereferencing is > clearly invalid. However, in order to allow common loop idioms, > pointer arithmetic one element beyond a array (memory) range is valid: Of course. But one element BEFORE the beginning of an array is invalid. In other words p + sizeof(p) is valid (assuming p is char[]), but p - 1 is not. In this instance, if p is a 0-terminated string, p + strlen(p) is always valid, even without the provision you mention, because the 0 is part of the object. But p + strlen(p) - 1 is not, if strlen(p) can be 0. Note that dereferencing or not is not relevant: some architectures have special registers for pointers that would cause traps just loading an invalid pointer (think: p at offset 0 of segment S, p-1 at offset max of segment S-1 -> load segment descriptor). FFmpeg probably does not run on any such architecture, though. But still, this is bad style. Regards, -- Nicolas George
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