CODEWITHSUNDEEP
c++gcc
The_Reaper
The_Reaper

Reputation: 157

How to enable _USE_UNIX98 (Gcc/C++ v2.96)

I've a C++ application that works in actual compilers (I compile it with eclipse). Now, I need compile it on a very old compiler version (gcc/c++ v2.96) on a Redhat 7.3 with Kdevelop.

When I compile the app it gives the following error: swprintf undeclared. wchar.h header it's included, but I saw this file in the RH7.3 OS and only declare this function if __USE_UNIX98 __USE_ISOC99 are declared.

How can I enable __USE_UNIX98?

Upvotes: 4

Views: 1539

Answers (2)

Jonathan Wakely
Jonathan Wakely

Reputation: 171253

From inspection of <features.h> defining _XOPEN_SOURCE to 500 or greater will cause __USE_UNIX98 to be defined

Upvotes: 2

user743382
user743382

Reputation:

GNU libc defines the features that should be enabled in all of its headers using a special system header <features.h>. If you define the appropriate macros, <features.h> will define __USE_UNIX98 for you.

The typical way to get all functions, regardless of what standard (if any) covers them, is by adding -D_GNU_SOURCE on the command-line. Getting only the functions covered by a specific standard requires defining the macro as specified in that standard using the value specified in that standard, such as -D_POSIX_C_SOURCE=200112L. The precise values that are supported on your particular implementation are probably easiest found by inspecting /usr/include/features.h manually.

Upvotes: 3

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