HELP!!

This is my program:

# include <stdio.h># include <sys/types.h># include <fcntl.h>

int main()

{

int p_button=NULL;

unsigned int x=0;

p_button=open("/dev/ttyS0",O_RDWR);

if(p_button<0)

{

printf("\nopen uart device ERROE!\n");

return 0;

}

for(x=200;x<256;x++)

{

write(p_button,&x,1);

printf("write rs232 end!\n");

read(p_button,&x,1);

printf("read rs232 end!\n");

if(x==0) {close(p_button);return 0;}

}

close(p_button);

}

These are the problems:

Severity Description Resource In Folder Location Creation Time

1 initialization makes integer from pointer without a cast test.c hello line 7 May 23, 2006 9:56:29 AM

1 implicit declaration of function `write&#39; test.c hello line 17 May 23, 2006 9:56:29 AM

1 implicit declaration of function `read&#39; test.c hello line 19 May 23, 2006 9:56:29 AM

1 implicit declaration of function `close&#39; test.c hello line 21 May 23, 2006 9:56:29 AM

They are warning !

But,it always die in "read",Why??

another problem :when I download program(*.exe) in the target though FTP, the problem can&#39;t run. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/blink.gif

Thanks!!