Why not delay the detection of the length to the first call of strlen?

 

What it should do:

-> Confirm the underlying buffer contains at least one NUL byte, if possible to be confirmed: This is done by the constructors.

-> Avoid repeated traversals for strlen: Cache the length.

-> Don't calculate the length, if not needed. Only do it at first use. Should be as efficient as a char* pointer (at least regarding the operations).

 

The confirmation of NUL is not always possible or needs different pre-conditions or different effort:

 - constructing from char*: We don't know the length of the buffer. Confirmation not possible.

 - constructing from char*+size of buffer: Can be done in O(n)

 - constructing from types with guaranteed NUL at the end, but possible intermediate NUL bytes: Already confirmed by type.