Error: Sem_union solution for storage size unknown problem _c language

Today, when compiling code, I was prompted with an error: ' Sem_union ' storage size is unknown

Problem reason: in the new 2.6 kernel about Union sem_union This consortium has been annotated and needs to write the consortium itself .

Solution: First define in C file:

Union Semun 
{
	int val;  
	struct Semid_ds *buf; 
	unsigned short *array;
} Sem_union;

It will then be able to find a pre-defined sem_union consortium at compile time.

Linux compile-time errors and solutions

(1) because it is a novice Linux, so now began to contact threading programming, according to an example of the Gun/linux Programming Guide to compile, the results of the following error:

Undefined reference to ' pthread_create '

Undefined reference to ' Pthread_join '

Problem Reason:

The Pthread library is not the default library of the Linux system, which requires the use of a static library libpthread.a, so that when you create a thread using Pthread_create () and call the Pthread_atfork () function to establish a fork handler, You need to link to the library.

Problem solving:

To add-lpthread parameters to the compilation

Gcc-o Thread Thread.c-lpthread

THREAD.C for your source files, don't forget to add the header file #include<pthread.h>

(2) Warning: built-in function strlen incompatible implicit declaration, built-in function exit incompatible implicit declaration

Problem reason: Because the function strlen in string, exit is inside Stdlib. No header files are added to the file string.h and Stdlib

Problem Resolution: Add header files to files String.h and stdlib

(3) Error: Sem_union storage size is unknown

Problem reason: In the new 2.6 kernel about Union sem_union This consortium has been annotated and needs to write the consortium itself.

Problem solving: First defined in C file

Union Semun {int val; struct semid_ds *buf; unsigned short *array;} sem_union;

It will then be able to find a pre-defined sem_union consortium at compile time.