下面程序的功能是：对字符串从小到大进行排序并输出，请填空。
#include"string.h"
#include"stdio.h"
sort(char *a[],int n)
int i,j;
char *p;
for(j=1;j＜=n-1;j++)
for(i=0;i＜n-j;i++)
if(______)＞0)
p=a[i];
a[i]=a[i+1];
a[i+1]=p;
main()
int i;
char *book[]="itisme","itisyou","howareyou","fine","goodnight","goodbye";
sort(______);
for(i=0;i＜6;i++)
printf("%s\n",book[i]);