void print2(struct book *ptr[],int n)//以标题先后输出
{
    int i,j;
    struct book *temp;
    for(i=0;i<n;i++)
    {
        for(j=i+1;j<n;j++)
        {
            if((strcmp(ptr[i]->title,ptr[j]->title))>0)
            {
                temp=ptr[j];
                ptr[j]=ptr[i];
                ptr[i]=temp;
            }        
        }
    }
    for(i=0;i<n;i++)
    {
        printf(" %s by %s:$%.2f\n",ptr[i]->title,ptr[i]->author,ptr[i]->value);
    }

}

看不明白