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<== Date ==>		<== Thread ==>

Subject:	sizeof with g++ > 5.2
From:	"Gofron, Kazimierz via Core-talk" <core-talk at aps.anl.gov>
To:	"core-talk at aps.anl.gov" <core-talk at aps.anl.gov>
Date:	Wed, 4 Mar 2020 18:22:01 +0000

Hi,

Since base is written in C, and many drivers are written in C++, we are seeing some issues for string, as discussed below.

https://epics.anl.gov/tech-talk/2020/msg00515.php

The g++ on Debian9 uses newer compiler than g++ > 5.2, and reports sizeof(string) up to 15.

http://www.cplusplus.com/forum/beginner/173925/

sizeof(std::string), in-object space for small string storage:
```
GNU libstdc++ (conforming implementation, GCC 5.2 or later): 32, 15
LLVM libc++: 24, 22
Microsoft msc++ 19.00 (VS 2015): 28, 15

```

Is there a replacement / better way to use sizeof?

mPollQueue(1, sizeof(acquisition_t))

Kazimierz Gofron

NSLS-II Controls Group

Brookhaven National Laboratory

(p) +1 (631) 344 5283

(f) +1 (631) 344 8085

(e) kgofron at bnl.gov

(w) www.bnl.gov/nsls2