CODEWITHSUNDEEP
cgccportability
romi
romi

Reputation: 171

gcc size of types

As the size of the types is not close in the standars of C, if not that there are a maximum and minimum size for them, I would like to know where I can find how gcc interpret this.

Where is in gcc documentation the size of the types they will take? Is there specify? I can not find that information, so i would like a few of help with it.

Thanks in advance.

--- Conclusions ---

Looking into all your comments, I finally get the information in this links to argue the answer

5.2.4.2.1 Sizes of integer types : http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1336.pdf

http://gcc.gnu.org/onlinedocs/gccint/Type-Layout.html

Upvotes: 4

Views: 5128

Answers (3)

Antti Haapala -- Слава Україні
Antti Haapala -- Слава Україні

Reputation: 133919

As per what others said you can see limits.h. However the better way to do yourself is to say what you mean. Thus #include <stdint.h> and then you can use

  • int32_t for exactly 32 bits
  • int_fast32_t for the fastest datatype that has at least 32 bits

However, if you want to store an array offset you should use size_t or ssize_t; likewise for an integer datatype that is big enough to store a pointer, use intptr_t.

Upvotes: 3

janneb
janneb

Reputation: 37208

It's not in the GCC documentation per se, but rather in the ABI documentation for each target system. E.g. for Linux x86_64 the ABI document is here: http://www.x86-64.org/documentation/abi.pdf

Details of each ABI that GCC supports is of course coded in the GCC sources, see e.g. chapter 17 in the GCC internals manual at http://gcc.gnu.org/onlinedocs/gccint/Target-Macros.html

Upvotes: 4

Robbie Dee
Robbie Dee

Reputation: 1977

For the minimum and maximum values, you can look in limits.h (or the equivalent in C99 and beyond - stdint.h, which includes limits.h).

For the sizes of a type, just use sizeof();

Upvotes: 2

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