how to check out wordsize on linux [closed]

Question

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 8 years ago.

As we can see a macro defined in stdint.h or bits/types.h etc.. which is __WORDSIZE. I don't know where to check out whether this macro is defined. Also, is there a way to checkout different size of the basic types without using the sizeof in c. I mean, is there a document exhibits the size of those variables?

Answer 1

Well, it depends on the platform. First, there are some requirements set by the C standard and/or the POSIX standard if you use UNIX. Things like sizeof(int) <= sizeof(long) or sizeof(char) == 1

Then the ABI has the final say. For example, on linux/freebsd/solaris on x86_64, they use a common ABI: http://people.freebsd.org/~obrien/amd64-elf-abi.pdf

3.1.2 in this document has the size for all types for this ABI