globalvartest.c

来自「Some simple source code to show specific」· C语言 代码 · 共 30 行

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <fcntl.h>
main()
{
int fd, num;
//"/dev/globalvar"
fd = open("/dev/globalvar", O_RDWR, S_IRUSR | S_IWUSR);
if (fd != -1 )
{
read(fd, &num, sizeof(int));
printf("The globalvar is %d\n", num);

printf("Please input the num written to globalvar\n");
scanf("%d", &num);
write(fd, &num, sizeof(int));

read(fd, &num, sizeof(int));
printf("The globalvar is %d\n", num);


close(fd);
}
else
{
printf("Device open failure\n");
}
}