#include <stdio.h>
#include <stdlib.h>
#define maximum 5
typedef struct blocklink
{
    char data[maximum];
    struct blocklink *next;
}BLOCKLINK;
int StringlengthBL(BLOCKLINK *h)//整个块链中字符的个数
{
    BLOCKLINK *p=h;
    int count=0;
    int i=0;
    while(p!=NULL)
    {
        if(i%maximum==0)
            p=p->next;
        if(p!=NULL)
        {
            if(p->data[i%maximum]!='$')
                count++;
        }
        i++;
    }
    return count;
}
int StringLength(char *h)//一个块中链的长度
{
    int count=0;
    while(h[count]>0)
        count++;
    return count;
}
BLOCKLINK *CreatBLink(char *t)//把一个字符数组中的元素存储到块链中
{
    BLOCKLINK *s,*p,*h;
    int i;
    p=h=(BLOCKLINK *)malloc(sizeof(BLOCKLINK));
    h->next=NULL;
    i=0;
    while(i<StringLength(t))
    {
        if(i%maximum==0)//如果i=0的话那么就新建一个节点
        {
            s=(BLOCKLINK*)malloc(sizeof(BLOCKLINK));
            p->next=s;
            s->next=NULL;
            p=s;
        }
        s->data[i%maximum]=t[i];
        i++;
    }
    while(i%maximum!=0)
    {
        s->data[i%maximum]='$';
        i++;
    }
    return h;
}
void Replace(BLOCKLINK *h,char *t,int i)//用t替换由h的第i字符开始的若干串
{
    int len=StringLength(t);
    if(i<1||i>StringlengthBL(h)||i<0)
    {
        printf("参数不合理，无法完成操作\n");
        return;
    }
    BLOCKLINK *p=h;
    int k;
    for(k=0;k<=(i-1)%maximum;k++)//找到第i位置所在的块
        p=p->next;
    int count=0;
    k=(i-1)%maximum;
    while(count<len)
    {
        p->data[k%maximum]=t[count];
        count++;
        k++;
        if(k%maximum==0)
            p=p->next;
    }

}
void SubStr(BLOCKLINK *h,char *t,int i,int len)
{
    if(i<1||i>StringlengthBL(h)||len<0||i-1+len>StringlengthBL(h))//从第i 个开始len个字符相当于i-1+len
    {
        printf("参数不合理，无法完成操作！\n");
        return;
    }
    BLOCKLINK *p=h;
    int k;
    for(k=0;k<=(i-1)%maximum;k++)
        p=p->next;
    int count=0;
    k=(i-1)%maximum;
    while(count<len)
    {
        if(p->data[k%maximum]!='$')
        {
            t[count]=p->data[k%maximum];
            count++;
        }
        k++;
        if(k%maximum==0)
            p=p->next;
    }
}
void StrCon(BLOCKLINK *h,char *t)
{
    BLOCKLINK *p,*s;
    p=h;
    while(p->next!=NULL)
        p=p->next;
    int i;
    for(i=0;i<StringLength(t);i++)
    {
        if(i%maximum==0)
        {
            s=(BLOCKLINK *)malloc(sizeof(BLOCKLINK));
            p->next=s;
            s->next=NULL;
            p=s;
        }
        p->data[i%maximum]=t[i];
    }
    while(i%maximum!=0)
    {
        s->data[i%maximum]='$';
        i++;
    }
}
void DisplayString(BLOCKLINK *h)
{
    BLOCKLINK *p;
    p=h;
    int count=0;
    int i=0;
    while(p!=NULL)
    {
        if(i%maximum==0)
        {
            p=p->next;
            if(p==NULL)
                break;
            printf("->");
        }
        printf("%c",p->data[i%maximum]);
        i++;
    }
    printf("\n");
}
int main()
{
    BLOCKLINK *b1;
    char c[maximum];
    int i;
    gets(c);
    printf("初始化块链b1\n");
    b1=CreatBLink(c);
    DisplayString(b1);
    printf("从第6个字符开始，取4个字符，形成新的串d\n");
    char d[maximum];
    int len=4;
    for(i=0;i<len;i++)
        d[i]=NULL;
    SubStr(b1,d,6,len);
    for(i=0;i<StringLength(d);i++)
        printf("%c",d[i]);
    printf("\n");
    printf("从b1的第5个字符开始，用串d替代\n");
    Replace(b1,d,5);
    DisplayString(b1);
    printf("将串d链接到b1之后\n");
    StrCon(b1,d);
    DisplayString(b1);
    printf("b1的长度：");
    printf("%d\n",StringlengthBL(b1));

    return 0;
}