__int64 equivalent in GCC?

[mentallysilent]

Hello,

I'm currently working on a project where I have to port a massive API written on ******* to Linux (My 7.10 box with gcc 4.1.3). The original code was written in MSVC++ and makes heavy use of the __int64 extension. I'm just wondering how to move this to g++? I've read somewhere that init64_t is an equivalent but comes from C. Any suggestions? Thanks muchly.

[dwhitney67]

Add this include to your project:

#include <inttypes.h>
Then use uint64_t or int64_t.

[mentallysilent]

Thanks so much. So then what is the difference between <stdint.h> and <inttypes.h>?

[Zugzwang]

Thanks so much. So then what is the difference between <stdint.h> and <inttypes.h>?

inttypes.h includes stdint.h and just adds more macros/functions. So both should be fine.

[mentallysilent]

And this is good for use with pure C++ right?

[dwhitney67]

Yes it is. Many features used in C++ have been inherited from C, including many of the functions in the C library.

[mentallysilent]

Thanks guys :)

[Jessehk]

Yes it is. Many features used in C++ have been inherited from C, including many of the functions in the C library.

AFAIK, that's incorrect. stdint.h is a C99 header and most C++ compilers haven't bothered implementing the C99 standard. GCC might be an exception, but I'm not sure.

I may be wrong. :)

[dwhitney67]

On my Fedora 9 system, which uses GCC 4.3.0, it has a 'cinttypes' header file, whereas with GCC 4.2.3 it doesn't exist.

However, even when attempting to compile with 'cinttypes' on F9, the following error is produced:

In file included from /usr/lib/gcc/i386-redhat-linux/4.3.0/../../../../include/c++/4.3.0/cinttypes:40,
from test.cpp:1:
/usr/lib/gcc/i386-redhat-linux/4.3.0/../../../../include/c++/4.3.0/c++0x_warning.h:36:2: error: #error This file requires compiler and library support for the upcoming ISO C++ standard, C++0x. This support is currently experimental, and must be enabled with the -std=c++0x or -std=gnu++0x compiler options.

[pansz]

And this is good for use with pure C++ right?

No, I can confirm that int64_t is not part of ISO C++98 Standard.

the int64_t is part of ISO C99 standard, which is incompatible with ISO C++98.

gcc support int64_t in C++ but that's not the standard.
visual c++ support __int64 but that again is not the standard.
My suggestion: only use int64_t in C, use of int64_t in C++ makes your source platform dependent. (some versions of gcc does not support int64 in c++)

[bender1234]

gah WTB more standarised c++

thx for the heads up though, I was struggling with the same here myself.

[Zugzwang]

Here is another solution: Use some cross-platform library such as SDL - They define their own integer types. This leaves such a problem to the developers of the library.

[MadCow108]

they probably just do something like this:


#ifdef WINDOWS
typedef __int64 Long64_t; //Portable signed long integer 8 bytes
typedef unsigned __int64 ULong64_t; //Portable unsigned long integer 8 bytes
#else
typedef long long Long64_t; //Portable signed long integer 8 bytes
typedef unsigned long long ULong64_t;//Portable unsigned long integer 8 byte

no need to link a library to get 64 bit integers :)

[Zugzwang]

they probably just do something like this:


#ifdef WINDOWS
typedef __int64 Long64_t; //Portable signed long integer 8 bytes
typedef unsigned __int64 ULong64_t; //Portable unsigned long integer 8 bytes
#else
typedef long long Long64_t; //Portable signed long integer 8 bytes
typedef unsigned long long ULong64_t;//Portable unsigned long integer 8 byte

no need to link a library to get 64 bit integers :)

It suffices to include the respective integer type header filed from SDL. Linking against it is also not required. Additionally, you can be sure to get support for more than just GCC in Linux and VC in Windows.

[napsy]

long long is C99;

so why not typedef long long int64_t?