转换：uid_t 到字符串，off_t 到字符串
我目前正在编写系统编程作业，其中一部分需要获取目录中文件的一些信息。
对于文件的统计信息，我们有 ctime() 函数，它将 time_t 类型转换为 string 并返回指向它的指针。
但是 uid_t 和 off_t 类型又如何呢？ 我在网上搜索并没有找到任何功能。或者如果没有任何功能，你能告诉我如何实现这样的功能吗？
I am currently writing a systems programming homework and in one part i need to get some information of a file in a directory.
for the stat of file, we have ctime() function which converts time_t type to string and returns a pointer to it.
but how about the uid_t and off_t types? I searched through to internet and couldnt find any function.. Or if there does not exist any function, can you tell me how to implement such a function please?
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两者都定义为算术类型 (http://www.opengroup .org/onlinepubs/009695399/basedefs/sys/types.h.html），并且在实践中是积极和完整的。 因此，您可以将其转换为 unsigned long long，然后使用 sprintf 和“%llu”来转换为字符串。
Both are defined as arithmetic types (http://www.opengroup.org/onlinepubs/009695399/basedefs/sys/types.h.html), and in practice are positive and integral. So you can just cast to unsigned long long, and use sprintf with "%llu" to convert to string.
size_t和off_t只是无符号整数类型。 （编辑：off_t很长？看，教训是，检查你的标题！）因此使用
sprintf（或其他）使用“%i”格式将它们转换说明符。编辑时：糟糕，当我回答时，您将
size_t更改为uid_t。uid_t在types.h中定义； 看这里。 （它也是一个无符号整型，但是是一个无符号短。）size_tandoff_tare just unsigned integral types. (Edit:off_tis a long? See, the lesson is, check your headers!)So use
sprintf(or whatever) to convert them using the "%i" format specifier.On edit: crap, you changed
size_ttouid_twhile I was answering.uid_tis defined intypes.h; look there. (It's also an unsigned integral type, but anunsigned short.)Linux 的 snprintf() 支持
size_t。 不确定它的可移植性如何，您需要仔细检查“CONFORMS TO”部分。对于
off_t，您可能需要转换为最大的无符号整数类型，即unsigned long并使用“lu”说明符。Linux' snprintf() supports the 'z' format specifier for values of type
size_t. Not sure how portable this is, you'll need to inspect the "CONFORMS TO" section closely.For
off_t, you might need to cast to the largest unsigned integer type, i.e.unsigned longand use a "lu" specifier.off_t是一个long int：format = "%ld"size_t是一个unsigned int：format = "% u"您可以在 sprintf 函数中使用这些格式将其转换为 char*。
off_tis along int: format = "%ld"size_tis anunsigned int: format = "%u"You can use these format in
sprintffunction to convert into a char*.使用 gcc 5.4.0 以下行：
printf("user #%ld did this or that!\n", uid);
引发以下警告：
..main.c:133:9: warning: format '%ld' Expects argument of type 'long int', but argument 2 has type 'uid_t {aka unsigned int} ' [-Wformat=]
我建议您也这样做并检查编译器的输出。 =)
Using gcc 5.4.0 the following line:
printf("user #%ld did this or that!\n", uid);
raised the following warning:
..main.c:133:9: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 2 has type ‘uid_t {aka unsigned int}’ [-Wformat=]
I would suggest you to do the same and check your compiler's output. =)