串的堆式存储结构

在C和C++语言中 ，提供一个称之为“堆”的共享空间，可以在程序运行过程中，系统利用函数malloc( )和free( )动态地申请或释放一块连续空间。

由于在C和C++语言中可以用指针对数组进行访问和操作，在串的存储和操作上也可以充分利用上述特性。

串的堆式存储结构类似于线性表的顺序存储结构，以一组地址连续的存储单元存放串值字符序列，其存储空间是在程序执行过程中动态分配的，而不是静态分配的。

串的堆式存储结构定义

Typedef struct {  char *ch;   //指针域，指向存放串值的存储空间基址   int length;  // 整型域：存放串长 }HString;

说明：在这种存储结构下，由于串仍然是以数组存储的字符序列表示，因此此类串的操作是先为新生成的串分配一个存储空间，然后进行“字符序列的复制”。例如，如串插入操作StrInsert(S,pos ,T)（将串T插入到串S的第pos字符之前）的算法是，为串S重新分配大小等于串S和串T长度之和的存储空间，然后进行将S和T串值复制到新分配存储空间中。

串的一系列实现

/* 串的堆式存储表示 */#include<stdio.h>#include<stdlib.h>#define OVERFLOW   -2//堆溢出#define OK          1//函数执行成功#define ERROR      -1//函数执行失败typedef int datatype;typedef struct {char* ch; //指针域，指向存放串值的存储空间基址int len; // 整型域：存放串长} HString;//初始化一个空串datatype InitHString(HString* s) {s->ch = (char*) malloc(sizeof(char));if (NULL == s->ch)return OVERFLOW;s->ch = NULL;s->len = 0;return OK;}//为串赋值datatype assigment_string(HString* s, const char* str) {if (s->ch)free(s->ch);int length = 0, i;while (str[length] != '\0')length++;s->ch = (char*) malloc(length * sizeof(char));if (!s->ch)return OVERFLOW;for (i = 0; i < length; i++)*(s->ch + i) = *(str + i);s->len = length;*(s->ch + s->len) = '\0';return OK;}//打印void PrintString(const HString* s) {int i = 0;while (*(s->ch + i) != '\0') {printf("%c", *(s->ch + i));i++;}printf("\n");}//求串的长度datatype GetLength(const HString* s) {int len = 0;while (*(s->ch + len) != '\0')len++;return len;}//查找某个字符的位置，返回位序datatype HSLocal(const HString* s, char c) {int i;for (i = 0; i < s->len; i++) {if (c == *(s->ch + i))return i + 1;}return -1;}//串的连接datatype HSCat(HString* s, const HString* t) {int i = 0;char* temp = (char*) malloc((s->len + t->len) * sizeof(char));if (!temp)return OVERFLOW;for (i = 0; i < s->len; i++)*(temp + i) = *(s->ch + i);free(s->ch); //释放防止内存泄漏for (i = 0; i < t->len; i++)*(temp + i + s->len) = *(t->ch + i);s->len += t->len;s->ch = temp; //使s->ch重新指向temp*(s->ch + s->len) = '\0';return OK;}datatype HSCopy(HString* to, const HString* from) {//如果目标串不为空则清空if(to->ch){free(to->ch);to->ch = NULL;to->len = 0;}int i = 0;to->len = from->len;to->ch = (char*) malloc(from->len * sizeof(char));if (!to->ch)return OVERFLOW;for (i = 0; i < from->len; i++)*(to->ch + i) = *(from->ch + i);*(to->ch + to->len) = '\0';return OK;}//在串s的pos位置处插入串tdatatype HSInsert(HString* s, const HString *t, int pos) {if (pos < 0 || pos > s->len)return ERROR;else {s->ch = (char*) realloc(s->ch, (s->len + t->len) * sizeof(char));int i, j = 1;//后移for (i = s->len + t->len - 1; i >= pos + t->len; i--) {*(s->ch + i) = *(s->ch + (s->len - j));j++;}//insert  for (i = 0; i < t->len; i++)*(s->ch + i + pos) = *(t->ch + i);}s->len += t->len;*(s->ch + s->len) = '\0';return OK;}//在串s的index位置删除长度为x个字符datatype HSdel(HString* s, int index, int x) {// index value invalidif (index < 0 || index > s->len)return ERROR;//  if x+index> s->lenif ((index + x) >= s->len)s->len = index;else {int i;for (i = index; i < s->len; i++) {*(s->ch + i) = *(s->ch + i + x);}s->len -= x;}*(s->ch + s->len) = '\0';return OK;}//串比较datatype HScomp(const HString* s1, const HString* s2) {int i = 0;for (i = 0; i < s1->len && i < s2->len; i++) {if (*(s1->ch + i) != *(s2->ch + i))return *(s1->ch + i) - *(s2->ch + i);}if (i < s1.len) {return 1;} else if (i < s2.len) {return -1;} else {return 0;}}/*串的提取 *   在串s中的index开始长度为length的子串提取到temp串中 * */datatype HSsub(HString* temp, const HString* s, int index, int length) {if (index < 0 || index > s->len)return ERROR;if (length > s->len)length = s->len - index;temp->len = length;temp->ch = (char*) malloc(length * sizeof(char));if (!temp->ch)return OVERFLOW;int i;for (i = 0; i < length; i++) {*(temp->ch + i) = *(s->ch + index + i);}*(temp->ch + temp->len) = '\0';return OK;}//串的替换，把串s的从index开始长度为length的子串，用串t替换掉datatype HSReplace(HString* s, int index, int length, const HString*t) {if (index < 0 || index > s->len)return ERROR;//如果length大于串s的长度就替换掉从index后的所有字符if (length > s->len)length = s->len;int i;for (i = 0; i < length; i++) {*(s->ch + i + index) = *(t->ch + i);}*(s->ch + s->len) = '\0';return OK;}int main(int argc, char** argv) {// bulid stringHString S;InitHString(&S);assigment_string(&S, "hello world!");PrintString(&S);printf("length=%d\n", GetLength(&S));#if 0//localionint local=HSLocal(&S,'w');printf("local=%d\n",local);free(S.ch);#endif #if 0// insertHString S1;InitHString(&S1);assigment_string(&S1,"****");HSInsert(&S,&S1,2);PrintString(&S);printf("length=%d\n",GetLength(&S));free(S1.ch);#endif#if 0// copyHString S2;InitHString(&S2);assigment_string(&S2,"beijing");HSCopy(&S,&S2);PrintString(&S);printf("length=%d\n",GetLength(&S));free(S.ch);free(S2.ch);#endif#if 0//cat HString S3;InitHString(&S3);assigment_string(&S3,"////");HSCat(&S,&S3);PrintString(&S);printf("length=%d\n",GetLength(&S));free(S3.ch);free(S.ch);#endif #if 0// delete HSdel(&S,2,5);PrintString(&S);printf("length=%d\n",GetLength(&S));free(S.ch);#endif #if 0// complar HString S4;InitHString(&S4);assigment_string(&S4,"hello world!");datatype ret=HScomp(&S,&S4);if(ret>0)printf("S>S4\n");else if(ret<0)printf("S<S4\n");elseprintf("S=S4\n");free(S4.ch);free(S.ch);#endif#if 0// subHString S5;HSsub(&S5,&S,2,5);PrintString(&S5);printf("length=%d\n",GetLength(&S5));free(S.ch);free(S5.ch);#endif#if 1       // replaceHString S6;InitHString(&S6);assigment_string(&S6, "************************************");HSReplace(&S, 2, 50, &S6);PrintString(&S);printf("length=%d\n", GetLength(&S));free(S6.ch);free(S.ch);#endif//free(S.ch);return 0;}