使用ssize_t供VS INT [英] Using ssize_t vs int

问题描述

我有，我可以在四个可能的方法的有一个的写一个函数：

I've got a function which I can write in one of the four possible ways:

int do_or_die(int retval);
int do_or_die(ssize_t retval);
ssize_t do_or_die(int t retval);   
ssize_t do_or_die(ssize_t retval);   

---

，然后它会与被调用的的这些方式库函数的两个的：

written = do_or_die(write(...)); // POSIX write returns ssize_t
printed = do_or_die(printf(...)); // printf returns int

问题

• 我应该使用哪种原型？


• 我应该给写和打印？
哪些类型


Questions

• Which prototype should I use?
• What types should I give to written and printed?

我想拥有的最强大和最标准的code，同时还具有只有一个 do_or_die 功能。

I want to have the most robust and standard code, while still having just one do_or_die function.

我在这种情况下使用C99，但如果答案是C11不同的，那么我想知道，也为未来的。

I am using C99 in this case, but if answer is different for C11, then I'd like to know that too, for future.

推荐答案

有在C或POSIX标准的sizeof（int）的＆GT难保; = sizeof的（ssize_t供），也不周围的其他方法。通常 ssize_t供比 INT 较大，但在C99安全和便携的选择是使用还会将intmax_t 来代替参数和返回值。

There's no guarantee in the C or POSIX standards that sizeof(int) >= sizeof(ssize_t), nor the other way around. Typically ssize_t is larger than int, but the safe and portable option in C99 is to use intmax_t instead for the argument and the return value.

的唯一保证你有WRT。之间的关系 INT 和 ssize_t供是：

The only guarantees you have wrt. the relationship between int and ssize_t are:



• INT 可存储至少在区间[-2 ^ 15 ... 2 ^ 15-1]每ISO C
值

• ssize_t供可存储至少范围在[-1 ... 2 ^ 15-1]每POSIX（见<一值href=\"http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html\"><$c$c>_POSIX_SSIZE_MAX).


• int can store values of at least the range [-2^15 ... 2^15-1] per ISO C
• ssize_t can store values of at least the range [-1 ... 2^15-1] per POSIX (see _POSIX_SSIZE_MAX).

（有趣的是，竟然没有了 ssize_t供可存储其正面范围的负同行的保证。这不是一个签署为size_t ，而是一个尺寸类型有一个错误值。）

(Interestingly, there isn't even a guarantee that ssize_t can store the negative counterparts of its positive range. It's not a signed size_t, but a "size type" with an error value.)

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