Re: Segments

On Fri, 17 Jan 2025 1:04:03 +0000, Keith Thompson wrote:

mitchalsup@aol.com (MitchAlsup1) writes:

On Thu, 16 Jan 2025 23:18:22 +0000, Keith Thompson wrote:

Terje Mathisen <terje.mathisen@tmsw.no> writes:
[...]

I do know that several people have created fast string libraries,
where any string that is short enough ends up entirely inside the dope
vector, so no heap allocation.

>
Some implementations of C++ std::string do this.  For example, the GNU
implementation appears to store up to 16 characters (including the
trailing null character) in the std::string object.

>
Why use an 8-byte pointer to store a string 16 or fewer bytes long ? !!

>
I don't understand.  What pointer are you referring to?
>
In the implementation I'm referring to, std::string happens to be 32
bytes in size.  If the string has a length of 15 or less, the string
data is stored directly in the std::string object (in the last 16 bytes
as it happens).  If the string is longer than that it's stored
elsewhere, and that 16 bytes is presumably use to manage the
heap-allocated data.

So, when it is stored elsewhere, how do you get from the struct to the
string ??
You use a pointer !!