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Answer 1

+1 A:

That ptr is displayed as nicely-formatted string and cwd as "byte buffer" is probably specific to gdb. In any case it shouldn't affect your application; according to man 3 getcwd, ptr should point to cwd (or it should be NULL if an error occurred). Can you use ptr without crashing the program?

oliver 2008-09-12 16:55:51

Answer 2

A:

What type is cwd? The above code snippet doesn't tell us that. It could be that ptr being a void* is treated differently by gdb.

Craig H 2008-09-12 16:58:28

Answer 3

+1 A:

The reason that cwd is printed differently in gdb is because gdb knows that ptr is a char * (I guess) and that cwd is an array of length 3500 (as shown in your output). So when printing ptr it prints the pointer value (and as a service also the string it points to) and when printing cwd it prints the whole array.

I don't see any reason why using cwd instead of ptr would lead to problems, but I would need to see some code to be sure.

mweerden 2008-09-12 16:59:27

Answer 4

+2 A:

I agree with mweerden. Trying something I believe is similar to your code, I get:

(gdb) print cwd
$1 = "/media", '\0' <repeats 782 times>, "\016���" ...
(gdb) print (char*) cwd
$2 = 0xbfc8eb84 "/media"

from gdb, so it seems that since cwd was defined as char cwd[3500], gdb prints the entire array, while if you tell gdb to interpret it as a char*, it will work as you expect. If your application crashes, I would assume it is because of something else.

ehdr 2008-09-12 17:22:24

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Confused by gdb print ptr vs print "%s"

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