map_normalfilewrite.c

关于进程间通信的代码集锦2

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

typedef struct{
	char name[4];
	int age;
}people;
int main(int argc,char** argv)
{
	int fd,i;
	people* p_map;
	char temp;
	fd=open(argv[1],O_CREAT|O_RDWR|O_TRUNC,00777);
//	lseek(fd,-1,SEEK_SET);
	lseek(fd,sizeof(people)*7-1,SEEK_SET);
//	lseek(fd,0,SEEK_SET);
	write(fd,"",1);
	p_map=(people*)mmap(NULL,sizeof(people)*10,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
	close(fd);
	temp='a';
	for(i=0;i<10;i++)
	{
		temp+=1;
		memcpy((*(p_map+i)).name,&temp,2);
		(*(p_map+i)).age=20+i;
	}
	printf("initialize over \n");
	sleep(10);
	munmap(p_map,sizeof(people)*10);
	printf("umap ok \n");
	
	return 0;
}