采用堆分配存储表示的串被称为堆串，与顺序串相比，地址空间仍是连续，但空间是在程序执行时动态分配的。
程序中会使用到的realloc函数：
//realloc ： （void *）reelloc (void *ptr,unsigned newsize);
//使用 ： char *str;
// str = (char *)realloc(str,20);
代码实现如下：
<span style="font-size:18px;">#pragma once
#include<iostream>
using namespace std;
#define MAX_SZIE 30
typedef struct
{
char *str;
int length;
}HeapString;
/*判断空*/
bool IsEmpty(HeapString *s);
/*初始化*/
void InintString(HeapString *s);
/*求长度*/
int Length(HeapString *s);
/*用字符串给串赋值*/
bool StrAssign(HeapString *s, char cstr[]);
/*打印*/
void StrPrint(HeapString *s);
/*在S的pos位置插入串T*/
bool StrInsert(HeapString *S, int pos, HeapString *T);
/*在S的pos位置删除长度为len的子串*/
bool StrDelete(HeapString *S, int pos, int len);
/*清空串*/
void ClearString(HeapString *s);
/*摧毁*/
void Destroy(HeapString *s);
/*从S的pos位置截取长为len的子串sub*/
bool SubString(HeapString *sub, HeapString *s, int pos, int len);
/*拼接*/
bool StringConcat(HeapString *T, HeapString *S, HeapString *S2);
/*拷贝*/
bool StrCopy(HeapString *T, HeapString *S);
/*比较*/
int StrCompare(HeapString *T, HeapString *S);
/*从S的pos位置开始定位子串T的初始位置*/
int StrIndex(HeapString *S, int pos, HeapString *T);
/*将S中的子串T全部用V替换*/
bool StrReplace(HeapString *S, HeapString *T, HeapString *V); <strong>
</strong></span><strong>
</strong>
<span style="font-size:18px;">#include "string.h"
/*堆串*/
void InintString(HeapString *s)
{
s->length = 0;
s->str = '\0';
}
bool IsEmpty(HeapString *s)
{
return s->length == 0;
}
int Length(HeapString *s)
{
return s->length;
}
void PrintString(char T[])
{
cout << T << endl;
}
bool StrAssign(HeapString *s, char cstr[])
{
int i = 0;
int len = 0;
if (s->str)
free(s->str);
for (i = 0; cstr[i] != '\0'; i++);
len = i;
if (!i)
{
s->str = '\0';
s->length = 0;
}
else
{
s->str = (char *)malloc(sizeof(char)*len);
if (s->str == NULL)
return false;
for (i = 0; i < len; i++)
{
s->str[i] = cstr[i];
}
s->length = len;
}
s->str[i] = cstr[i];
s->length = i;
}
void StrPrint(HeapString *S)
{
int i = 0;
for (i = 0; i < S->length; i++)
{
cout <<S->str[i];
}
cout << endl;
}
void ClearString(HeapString *s)
{
if (s->str)
free(s->str);
s->str = '\0';
s->length = 0;
}
void Destroy(HeapString *s)
{
if (s->str)
free(s->str);
s->str == NULL;
}
bool SubString(HeapString *sub, HeapString *s, int pos, int len)
{
if (sub->str)
free(sub->str);
if (pos < 0 || pos > s->length || len <= 0 || len > s->length - pos + 1)
return false;
sub->str = (char *)malloc(sizeof(char)*len);
if (sub->str == NULL)
return false;
int i = 0;
for (; i < len; i++)
{
sub->str[i] = s->str[i + pos - 1];
}
sub->str[len] = '\0';
sub->length = len;
}
bool StringConcat(HeapString *T, HeapString *S1, HeapString *S2)
{
T->str = (char *)realloc(T->str, sizeof(char)*(S1->length + S2->length));
if (T->str == NULL)
return false;
int i = 0;
for (; i < S1->length; i++)
{
T->str[i] = S1->str[i];
}
for (i = 0; i < S2->length; i++)
{
T->str[S1->length + i] = S2->str[i];
}
T->str[S1->length + S2->length] == '\0';
T->length = S1->length + S2->length;
return true;
}
bool StrCopy(HeapString *T, HeapString *S)
{
if (S->str == '\0')
return false;
T->str = (char *)realloc(T->str, sizeof(char)*(S->length));
if (T->str == NULL)
return false;
for (int i = 0; i < S->length; i++)
T->str[i] = S->str[i];
T->length = S->length;
return true;
}
int StrCompare(HeapString *T, HeapString *S)
{
int i = 0;
for (; i < T->length && i < T->length; i++)
{
if (T->str[i] != S->str[i])
{
if (T->str[i] > S->str[i])
return 1;
return -1;
}
}
if (T->length > T->length)
return 1;
else if (T->length < T->length)
return -1;
return 0;
}
bool StrDelete(HeapString *S, int pos, int len)
{
int i = 0;
char *p;
if (pos<0 || pos > S->length || len < 0 || len > S->length - pos + 1)
return false;
p = (char*)malloc(S->length - len);
if (p == NULL)
return false;
for (i = 0; i <pos - 1; i++)
{
p[i] = S->str[i];
}
for (i = pos - 1; i < S->length - len; i++)
{
p[i] = S->str[i+len];
}
S->length = S->length - len;
S->str = p;
return true;
}
int StrIndex(HeapString *S, int pos, HeapString *T)
{
if (pos < 0 || pos > S->length || IsEmpty(T))
return 0;
int i = pos - 1;
int j = 0;
while (i < S->length && j < T->length )
{
if (S->str[i] == T->str[j])
{
i++;
j++;
}
else
{
i = i - j + 1;
j = 0;
}
}
if (j >= T->length)
return i - j + 1;
else
return -1;
}
bool StrInsert(HeapString *S, int pos, HeapString *T)
{
int i = 0;
int s_len = S->length;
int t_len = T->length;
if (pos < 0 || pos - 1 >= S->length)
return false;
S->str = (char *)realloc(S->str, (S->length + T->length)*sizeof(char));
if (S->str == NULL)
{
cout << "内存分配失败" << endl;
return false;
}
for (i = S->length - 1; i >= pos - 1; i--)
{
S->str[i + T->length ] = S->str[i];
}
for (i = 0; i<T->length; i++)
{
S->str[pos - 1 + i] = T->str[i];
}
S->length += T->length;
//S[i] = '\0';
return true;
}
bool StrReplace(HeapString *S, HeapString *T, HeapString *V)
{
int i = 1;
int flag;
if (IsEmpty(T))
return false;
do
{
i = StrIndex(S, i, T);
if (i)
{
StrDelete(S, i, Length(T));
int flag = StrInsert(S, i, V);
if (!flag)
return false;
i += Length(V);
}
} while (i);
return true;
}</span><span style="font-size:18px;">#include "string.h"
void main()
{
HeapString s1, s2, sub,T;
char ch[MAX_SZIE+1];
char a[] = "abcdefdeg";
char b[] = "de";
char c[] = "XY";
InintString(&s1);
//cout <<"请输入第1个串:"<< endl;
//gets_s(ch);
//StrAssign(&s1, ch);
StrAssign(&s1, a);
cout << "输出串s1: " << endl;
StrPrint(&s1);
//SubString(&sub, s1, 2, 3);
//StrPrint(&sub);
InintString(&s2);
//cout << "请输入第2个串:" << endl;
//gets_s(ch);
StrAssign(&s2, b);
cout << "输出串s2: " << endl;
StrPrint(&s2);
cout << endl;
//InintString(&T);
//StringConcat(&T, &s1, &s2);
//StrPrint(&T);
//StrCopy(&s1, &s2);
//StrPrint(&s1);
//cout << StrCompare(&s1, &s2) <<endl;
//StrDelete(&s1, 2, 3);
cout<<StrIndex(&s1, 2, &s2)<<endl;
InintString(&sub);
StrAssign(&sub, c);
StrPrint(&sub);
StrReplace(&s1,&s2,&sub);
//StrInsert(&s1, 2, &sub);
StrPrint(&s1);
getchar();
}</span>
原文：http://blog.csdn.net/irean_lau/article/details/45920199
