4 ms·

Few of the top of my head: 1. Performance reasons. For example: zero copy data structures, mutable data structures, controlling data locality. 2. Direct memor

Few of the top of my head: 1. Performance reasons. For example: zero copy data structures, mutable data structures, controlling data locality. 2. Direct memory mapped hardware access. For example: device drivers, kernel, embedded systems, microcontrollers. 3. Bitwise and machine specific conversions. For example: endianess conversions. 4. Structure type coercion. For example: object systems, tagged data structures etc.

pjmlp 13y ago
All of those examples are possible in safe systems programming languages like Modula-2 and Ada, with the difference that only the tiny spot where it matters is marked explicitly unsafe. Whereas in C there is no way to distinguish between unsafe and safe code.
numeromancer 13y ago
2. Direct memory mapped hardware access. For example: device drivers, kernel, embedded systems, microcontrollers. Of course doing this usually means your code isn't portable, sometimes not even to other versions of the same compiler. I often wish C had a defined order for bitfields, for example. One of the things I do to help debug & test embedded code is to factor out code which isn't dependent on the hardware platform (eg communication protocols) into a library, and compile it for, and write test programs to test them on, the host. So even embedded code is often best written to be as portable as possible.
fanf2 13y ago
If you are doing unsafe or machine-dependent endurance conversion code, you are almost certainly doing it wrong. http://commandcenter.blogspot.co.uk/2012/04/byte-order-fallacy.html http://commandcenter.blogspot.co.uk/2012/04/byte-order-falla...
- deletes 13y ago
  Thank you for that link. #leaves to check some old code . . . #comes back Apparently my younger self knew what he was doing. ( The conversion is done correctly :shocked: )
- csmithuk 13y ago
  That's a great article - thanks for posting.
- mcguire 13y ago
  Sometimes I wonder about Rob. "In fact, C may be part of the problem: in C it's easy to make byte order look like an issue. If instead you try to write byte-order-dependent code in a type-safe language, you'll find it's very hard. In a sense, byte order only bites you when you cheat."
- fanf2 13y ago
  "endurance"?! Damn you, autocorrect.
mcguire 13y ago
Oddly enough, I've spent the last week playing around with type-agnostic garbage collection.

pjmlp 13y ago

All of those examples are possible in safe systems programming languages like Modula-2 and Ada, with the difference that only the tiny spot where it matters is marked explicitly unsafe. Whereas in C there is no way to distinguish between unsafe and safe code.

numeromancer 13y ago

2. Direct memory mapped hardware access. For example: device drivers, kernel, embedded systems, microcontrollers. Of course doing this usually means your code isn't portable, sometimes not even to other versions of the same compiler. I often wish C had a defined order for bitfields, for example. One of the things I do to help debug & test embedded code is to factor out code which isn't dependent on the hardware platform (eg communication protocols) into a library, and compile it for, and write test programs to test them on, the host. So even embedded code is often best written to be as portable as possible.

fanf2 13y ago

If you are doing unsafe or machine-dependent endurance conversion code, you are almost certainly doing it wrong. http://commandcenter.blogspot.co.uk/2012/04/byte-order-fallacy.html http://commandcenter.blogspot.co.uk/2012/04/byte-order-falla...

deletes 13y ago
Thank you for that link. #leaves to check some old code . . . #comes back Apparently my younger self knew what he was doing. ( The conversion is done correctly :shocked: )
csmithuk 13y ago
That's a great article - thanks for posting.
mcguire 13y ago
Sometimes I wonder about Rob. "In fact, C may be part of the problem: in C it's easy to make byte order look like an issue. If instead you try to write byte-order-dependent code in a type-safe language, you'll find it's very hard. In a sense, byte order only bites you when you cheat."
fanf2 13y ago
"endurance"?! Damn you, autocorrect.

mcguire 13y ago

Oddly enough, I've spent the last week playing around with type-agnostic garbage collection.