Conversion: uid_t to string, off_t to string

Question

Hello,

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?

thanks in advance...

Answer 1

size_t and off_t are just unsigned integral types. (Edit: off_t is 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_t to uid_t while I was answering. uid_t is defined in types.h; look there. (It's also an unsigned integral type, but an unsigned short.)

Answer 2

off_t is a long int: format = "%ld"

size_t is an unsigned int: format = "%u"

You can use these format in sprintf function to convert into a char*.

Answer 3

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 long and use a "lu" specifier.

Answer 4

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.