Go Call C code example

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1. Code Features:
   

   Invokes a POSIX shared memory interface to write and read shared memory data;

2. Code:

package main/* #cgo  LDFLAGS: -lrt#include <sys/mman.h> #include  <sys/stat.h > #include  <fcntl.h> #include  <unistd.h> #include  <stdlib.h> #include   <stdio.h> #include  <sys/types.h>*/import  "C" import  "unsafe" import  "FMT" Import   "OS" Func main ()  {name := c.cstring ("Testshm") defer c.free (unsafe. Pointer (name)) Fd, err := c.shm_open (Name, c.int (c.o_rdwr| c.o_creat),  0) if err != nil {fmt. Println (Err. Error ())}fmt. Printf ("fd:%d",  int (FD)) ret, err := c.ftruncate (fd, 1024*1024) if err !=  nil | |  ret != 0 {fmt. Println ("truncate failed.") Os. Exit (1)}strtest :=  ' hello, test write to shared memory ' content :=  c.cstring (strtest) res, err := c.write (Fd, unsafe. Pointer (content),  c.size_t (Len (strtest))) if err != nil | |  res == -1 {fmt. Println ("write to shared memory failed.") Os. Exit (1)}c.lseek (fd, 0, c.seek_set)//pread := make ([]byte, 100) pRead :=  C.malloc (Defer c.free) (PRead) Bytesread, err := c.read (Fd, unsafe. Pointer (PRead),  100) if err != nil {fmt. Println (Err. Error ()) OS. Exit (1)}fmt. Printf ("bytes read :%d, str are:%s",  bytesread, string (C.gobytes (pRead, 100 ))) C.getchar () C.shm_unlink (name)}

3. Note that the imported header file Comment line and the import code line of the Golang must have no blank line directly;