串的堆分配存储表示

串的堆分配存储表示 方法仍然以一组地址连续的存储单元表示，但它们的存储

空间是在程序执行过程中动态分配的。

堆串类型定义

typedef strcut HString

{

char *ch; //若是非空串，则按串长分配存储区，否则ch为NULL

int length; //串的长度

}HString;

堆串常用基本操作的算法描述

串赋值

int StrAssign(HString &S, char *chars)

{

int i = 0, j;

if (S.ch != NULL)

free(S.ch);

while (chars[i] != '\0')

i++;

if (!i)

{

S.ch = NULL;

S.length = 0;

}

else

{

if (!(S.ch = (char *)malloc(i*sizeof(char))))

exit(OVERFLOW);

for (j=0; j<i; j++)

S.ch[j] = chars[j];

S.length = i;

}

return OK;

}

串清空

int ClearString(HString &S)

{

if (S.ch)

{

free(S.ch);

S.ch = NULL;

}

S.length = 0;

return OK;

}

求串长

int StrLength(HString &S)

{

return (S.length);

}

串比较

int StrCompare(HString S, HString T)

{

int i;

for (i=0; i<S.length && i<T.length; i++)

if (S.ch[i] ! = T.ch[i])

return S.ch[i]-T.ch[i];

return S.length - T.length;

}

串插入

int StrInsert(HString &S, int pos, HString T)

{

int i;

if (pos<1 || pos>S.length+1)

return ERROR;

if (T.length)

{

if (!(S.ch = (char*)realloc(S.ch, (S.length+T.length)*sizeof(char))))

exit(OVERFLOW);

for (i=S.length; i>=pos; i--)

S.ch[T.length+i] = S.ch[i];

for(i=1; i<=T.length; i++)

S.ch[pos-1+i] = T.ch[i];

S.length = S.length + T.length;

}

retur OK;

}

串连接

int Concat(HString &T, HString S1, HString S2)

{

int i;

if (T.ch)

free(T.ch);

if (!(T.ch = (char*)malloc((S1.length+S2.length)*sizeof(char))))

exit(OWERFLOW);

T.length = S1.length+S2.length;

for (i=0; i<S1.length; i++)

T.ch[i] = S1.ch[i];

for (i=0; i<S2.length; i++)

T.ch[S1.length+i] = S2.ch[i];

return OK;

}

求子串

int SubString(HString &sub, HString S, int pos, int len)

{

int i;

if (pos<1 || pos>S.length || len<0 || len>length-pos+1)

return ERROR;

if (sub.ch)

free(sub.ch);

if (!len)

{

sub.ch = NULL;

sub.length = 0;

}

else

{

sub.ch = (char*)mallco(len*sizeof(char));

if (sub.ch == NULL)

exit(OWERFLOW);

for (i=0; i<len; i++)

sub.ch[i] = S.ch[pos+i];

sub.length = len;

}

return OK;

}



[cpp] view
plaincopy

#include <stdio.h>

#include <malloc.h>

#include <stdlib.h>



typedef struct HString

{

char *ch;

int length;

}HString;



int SubString(HString &sub, HString S, int pos, int len)

{

int i;

if (pos<0 || pos>S.length || len>S.length-pos+1)

return 1;

if (sub.ch)

free(sub.ch);

if (!len)

{

sub.ch = NULL;

sub.length = 0;

}

else

{

sub.ch = (char*)malloc(len*sizeof(char));

if (sub.ch == NULL)

exit(1);

for (i=0; i<len; i++)

sub.ch[i] = S.ch[pos+i];

sub.length = len;

}

return 0;

}



int main(void)

{

int i;

HString S, sub;

S.ch = "helloworld!";

S.length = 11;

sub.ch = NULL;

sub.length = 0;

SubString(sub, S, 5, 5);

for (i=0; i<5; i++)

printf("%c", sub.ch[i]);

printf("\n");

return 0;

}