C实现数据结构之串的堆分配存储表示

也叫变长分配存储表示

定义结构体

typedef struct HString {
	char *ch;//指针指向新开辟的空间
	int   length;//用表示字符串的长度表示字符串的结束
}HString;

初始化

void InitString(HString *S) {
	S->ch = NULL;
	S->length = 0;
}

打印输出

void PrintString(HString *S) {
	for(int i=0;i<S->length;i++)
		printf("%c", S->ch[i]);
	printf("\n");
}

给串赋值

void StrAssign(HString *S, char *str) {
	if (S->ch != NULL)free(S->ch);

	int len = strlen(str);
	S->ch = (char*)malloc(sizeof(char)*len);
	for (int i = 0; i < len;i++) {
		S->ch[i] = str[i];
	}
	S->length = len;

}

串复制

void StrCopy(HString *S, HString *T){
	//T:abc    ——>      S:abc  
  	int Tlen = StrLength(T);

	if (S->ch != NULL) free(S->ch);
	S->ch = (char*)malloc(sizeof(char)*Tlen);
	assert(S->ch != NULL);

	for (int i = 0; i < Tlen; i++) {
		S->ch[i] = T->ch[i];
	}
	S->length = Tlen;
}

串比较

int  StrCompare(HString *S, HString *T) {
	if (S->length == 0 && T->length == 0) return 0;
	int res = 0;abc       VS       //abc

	int i=0, j=0;
	while (i<S->length && j<T->length) {//当S和T串长度相等时,比较字符的ASCII码
		if (S->ch[i] < T->ch[j])///abc   VS  efg
			return -1;
		else if(S->ch[i]>T->ch[j])//efg  VS abc
			return 1;
		else {//abc   VS  abc
			i++;
			j++;
		}
	}
	//i>S->length || j>T->length 跳出循环说明T,S串数目不等
	if (j < T->length) {//若j满足条件则说明i>S->length，先跳出循环，则T串数目比S串多
		res = -1;
	}
	if(i<S->length) {//S串数目比T串多
		res = 1;
	}
	return res;

}

串连接

void StrConcat(HString *T, HString *s1, HString *s2) {
	int s1_len = StrLength(s1);
	int s2_len = StrLength(s2);

	if (T->ch != NULL)free(T->ch);
	T->ch =(char*) malloc(sizeof(char)*(s1_len + s2_len));
	
	int i, j;
	for (i= 0; i < s1_len; i++) {
		T->ch[i] = s1->ch[i];
	}
	for (j = 0; j < s2_len; j++) {
		T->ch[i + j] = s2->ch[j];
	}
	T->length = s1_len + s2_len;
}

取子串

void SubString(HString *S, HString *sub, int pos, int len) {
	if (len<0 || len>S->length || pos<0 || pos>S->length) return;

	if (sub->ch != NULL)free(sub->ch);

	sub->ch = (char*)malloc(sizeof(char) * len);
	assert(sub->ch != NULL);

	for (int i = 0; i < len; i++) {
		sub->ch[i] = S->ch[i + pos];
	}
	sub->length = len;
}

指定位置前插入串

void StrInsert(HString *S, int pos, HString *T) {
	//从最后一个元素开始往后移动T串的长度个距离
	int T_len = StrLength(T);
	if (T_len == 0)return;
	if (pos < 0 || pos>T_len) return;

	//重新开辟空间
	char *ch = (char*)realloc(S->ch, sizeof(char)*(S->length + T_len));
	assert(ch != NULL);
	S->ch = ch;

	for (int i = S->length - 1; i >= pos; i--) {
		S->ch[i + T_len] = S->ch[i];
	}

	for (int j = 0; j < T_len; j++) {
		S->ch[pos + j] = T->ch[j];
	}
	S->length += T_len;
}

指定位置删除串

void StrDelete(HString *S, int pos, int len) {
	if (pos<0 || pos>S->length)
		return;
	if (len <= 0 || len > S->length)
		return;

	//往前移动len个单位
	for (int i = 0; i < S->length; ++i) {
		S->ch[pos + i] = S->ch[pos + i + len];
	}
	S->length -= len;
}

清空串

void StrClear(HString *S) {
	S->length = 0;
	if (S->ch != NULL)
		free(S->ch);
	S->ch = NULL;
}