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0 pointssegfaultbuserr6y ago0 comments

Well, it's not lost in C itself. But in the practice of modern C programming, it's often sacrificed in favor of using integers of exact sizes (uintN_t), and many programs perform bitwise operation by assuming an exact size of integer. By C99, they are guaranteed to have the same number N of bits across all implementations, and they are included only if the implementation supports it. So the programs using them is standard C, but not 100% portable, there is no requirement in C to implement exact-width integers.

Although modification of most programs shouldn't be difficult (there is uint_leastN_t), also, C compilers can be modified to treat extra bits as if they don't exist to allow existing programs to work again.

0 pointssegfaultbuserr6y ago0 comments

0 comments

5 comments · 1 top-level

pjc506y ago· 4 in thread

This is the other way round though; code using "int" is a disaster for portability, because you don't know what you're actually getting. So people use uintN_t to get something specific which behaves the same way on different platforms - i.e. portable.

You can always #define or typedef uintN_t to a machine type. You can't re-typedef int. You can #define it, but people will hate you.

TwoBit6y ago

Even worse than int is long. So much old Unix code that was (incorrectly) using long to store pointer-sized types got broken on other 64 bit platforms.

TazeTSchnitzel6y ago

That was an interesting choice by Microsoft. I wonder if it broke 32-bit Windows code? https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_m...

burfog6y ago

I'm surprised that it isn't normal to provide a pragma for that. Something like this:

  #pragma push intsizes 1 2 2 4 0
  #include <yimage.h> // old 16-bit header
  #pragma pop

  #pragma push intsizes 1 2 4 8 16
  #include <servertypes.h> // uses 128-bit long long
  #pragma pop

pjc506y ago

That makes it completely impossible while reading code to tell what the size of int is even on your system. And worsens header file include order problems.

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