这一步是什么意思？交换的是什么？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    char *s[3], st[3][10], **p, *t;
    int i, j;
    for (i=0, printf("Please enter 3 strings: "); i<3; s[i]=st[i], scanf("%s", s[i++]));
    for (i=0; i<3; i++)
        for (j=i+1; j<3; strcmp(s[i], s[j])>0 ? t=s[i], s[i]=s[j], s[j]=t, j++ : j++);
    for (p=s; p<s+3; printf("%s ", *p++));
    printf("\n");
    system("pause");
    return 0;
}

﹉

t=s[i], s[i]=s[j], s[j]=t