#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<malloc.h> 
typedef char Elemtype;
typedef int Datatype;
typedef struct {
	Elemtype *ch;   //指標域，指向存放串值的儲存空間基址
   	int length;  // 整型域：存放串長 
}HString;

Datatype Init(HString *s);
Datatype Assign(HString *s,Elemtype str[]);
void Print(HString* s);
Datatype Concat(HString *s,HString *q);//連線 malloc版 
Datatype Concat2(HString *s,HString *t);//連線 realloc版 
Datatype Replace(HString *S,HString T,HString V);//替換
Datatype Insert(HString *S,int pos,HString *T);//插入

int main(){
	Elemtype ar[]="aaabcc**d",br[]="$$$",cr[]="bc";
	HString t,p,q;
	Init(&t);
	Assign(&t,ar);
	Print(&t) ;
	Init(&p);
	Assign(&p,br);
	Init(&q);
	Assign(&q,cr);
	Concat2(&t,&p);
	Print(&t);
	Insert(&t,2,&p);
	Print(&t);
	Replace(&t,q,p);
	Print(&t);
	return 0;
}
Datatype Init(HString *s){
	s->ch=(Elemtype *)malloc(sizeof(Elemtype));
	if(s->ch==NULL) return 0;
	s->ch='\0';
	s->length=0;
	return 1;
}

Datatype Assign(HString *s,Elemtype str[]){
	if(s->ch) free(s->ch);
	int lenth=0,i;
	while(str[lenth]!='\0')
		lenth++;
	s->ch=(Elemtype *)malloc(sizeof(Elemtype) * lenth);
	if(!s->ch) return 0;
	for(i=0;i<lenth;i++)
		*(s->ch+i)=str[i];
	s->length=lenth;
	*(s->ch+s->length)='\0';
	return 1;
}

void Print(HString* s){
	int i = 0;  
    while (*(s->ch + i) != '\0') {  
        printf("%c", *(s->ch + i));  
        i++;  
    }  
    printf("\n");  
}

Datatype Concat(HString *s,HString *t){
	Elemtype *temp;
	temp=(Elemtype *)malloc(sizeof(Elemtype) * (s->length+t->length));
	int i=0;
	if(!temp ) return 0;
	for(i=0;i<s->length;i++)
		*(temp+i)=*(s->ch+i);
	free(s->ch);
	for(i=0;i<t->length;i++)
		*(temp+s->length+i)=*(t->ch+i);
	s->length+=t->length;
	s->ch=temp;
	*(s->ch+s->length)='\0';
	return 1;
}

Datatype Concat2(HString *s,HString *t){
	int len=s->length;
	s->ch=(Elemtype *)realloc(s->ch,sizeof(Elemtype) * (s->length+t->length));
	int i=0;
	for(i=0;i<t->length;i++){
		*(s->ch+s->length+i)=*(t->ch+i);
	}
	s->length+=t->length;
	*(s->ch+s->length)='\0';
	return 1;
}

Datatype Replace(HString *S,HString T,HString V){
	int k,count=0,i=count,j=0;
	while(i>=0&&i<S->length&&j<T.length){
		if(*(S->ch+i)==*(T.ch+j)) {
			i++;j++;
		}
		else {
			i=i-j+1;
			j=0;
		}
	}
	if(j>=T.length) count=i-T.length;
	else count=0;
	Elemtype *temp;
	temp=(Elemtype *)malloc(sizeof(Elemtype) * (S->length-count-T.length));
	int y=0;
	for(i=count+T.length;i<S->length;i++)
	{
			*(temp+y)=*(S->ch+i);
			y++;
	}

	S->ch=(Elemtype *)realloc(S->ch,sizeof(Elemtype)*(S->length-T.length+V.length));
	
	y=0;
	for(i=count;i<count+V.length;i++) 
	{
		*(S->ch+i)=*(V.ch+y);
		y++;
	}
	y=0;
	for(i=count+V.length;i<S->length-T.length+V.length;i++){
		*(S->ch+i)=*(temp+y);
		y++;
	}
		
	S->length=S->length-T.length+V.length;
	*(S->ch+S->length)='\0';
	return 1;
}

Datatype Insert(HString *S,int pos,HString *T){
	if(pos>S->length||pos<0) return 0;
	else {
		S->ch=(Elemtype *)realloc(S->ch,(S->length+T->length)*sizeof(Elemtype));
		int i,j=1;
		for(i=S->length+T->length-1;i>=pos+T->length;i--){
			*(S->ch+i)=*(S->ch+S->length-j);
			j++;
		}
		for(i=0;i<T->length;i++)
			*(S->ch+i+pos)=*(T->ch+i);
	}
	S->length+=T->length;
	*(S->ch+S->length)='\0';
}