堆串HString的基本创建

#include <iostream>
using namespace std;
#include <malloc.h>
#include <stdio.h>
#define TURE 1
#define FALSE 0
#define OK 1
#define ERROR 0
#define IINFEASIBLE -1
#define OVERFLOW -2


typedef char ElemType;
typedef int Status;

typedef struct {
    char *ch;//若是非空串，则按串长分配存储区，否则ch为NULL
    int length;//串长度
}HString;


Status StrAssign(HString &T,char * chars)//生成一个其值等于串常量chars的串T
{
    int i,j;
    if(T.ch)
        free(T.ch);//释放T原有空间
    char *c =NULL;

    for(i=0,c=chars; *c;++i,++c);//求chars的长度
    if(!i)//如果chars长度为0
    {
        T.ch=NULL;
        T.length = 0;
    }
    else
    {
        if(!(T.ch = (char*)malloc(i*sizeof(char))))
            exit(OVERFLOW);
        for(j=0;j<i;j++)
        {
            T.ch[j]=chars[j];
        }
        T.length=i;
    }
    return OK;
}

Status Concat(HString &T,HString s1,HString s2)//用T返回由s1和s2连接而成的新串
{
    if(T.ch)
        free(T.ch);//释放旧空间
    if(!(T.ch=(char*)malloc((s1.length +s2.length)*sizeof(char))))
        exit(OVERFLOW);
    for(int i=0;i<s1.length;++i)
    {
        T.ch[i]=s1.ch[i];
    }
    T.length = s1.length + s2.length;
     for(int i=0;i<s2.length;++i)
    {
        T.ch[s1.length+i]=s2.ch[i];
    }
    return OK;
}

int StrCompare(HString s,HString T)
{//若s>T,则返回值>0;若s=T,则返回值=0;若s<T,则返回值<0
    for(int i=0;i<s.length&&i<T.length;++i)
    {
        if(s.ch[i]!=T.ch[i])
            return s.ch[i] -T.ch[i];//第一个不相等的字符ASCII值
    }
    return s.length - T.length;
}

Status SubString(HString &Sub,HString s,int pos,int len)
{//用Sub返回串s的第pos个字符起长度为len的子串
    if(pos<1 || pos>s.length || len<0 || len>s.length-pos+1)
        return ERROR;
    if(Sub.ch)
        free(Sub.ch);//释放旧空间
    if(!len)
    {
        Sub.ch = NULL;
        Sub.length = 0;//空子串
    }
    else//完整子串
    {
        Sub.ch = (char*)malloc(len*sizeof(char));
        for(int i=0;i<len;i++)
        {
            Sub.ch[i] = s.ch[i+pos-1];
        }
        Sub.length = len;
    }
    return OK;
}

int Index(HString s,HString T,int pos)//返回子串T在主串s中第pos个字符之后的位置。若不存在，则函数值为0
{
    int i = pos;
    int j = 0;
    while(i<s.length && j<T.length)
    {
        if(s.ch[i]==T.ch[j])//继续比较后面字符
        {
            ++i;
            ++j;
        }
        else
        {
            i = i-j+1;//指针后退重新开始匹配
            j = 0;
        }
    }
    if(j>T.length-1)
        return i-T.length+1;
    else return 0;
}
/*void Get_nextval(HString T,int nextval[])
{
    int i = 1;
    int j = 0;
    nextval[1] = 0;
    while(i<T.length)
    {
        if(j==0 || T[i]==T[j])
        {
            ++i;++j;
            if(T[i]!=T[j])
                nextval[i]=j;
            else
                nextval[i] = nextval[j];
        }
        else
            j = neextval[j];
    }

}*/

/*int Index_KMP(HString s,SString T,int pos)
{
    Get_nextval(T,nextval);
    int i = pos;
    int j = 1;
    while(i<=s[0] && j<=T[0])
    {
        if(j==0 || s[i]==T[i])
        {
            ++i;++j;
        }
        else
            j = next[j];
    }
    if(j>T[0])
        return i-T[0];
    else return 0;

}*/
int Strlength(HString s)
{
    return s.length;
}
void Print(HString s)
{
    int i;
    for(i=0;i<s.length;i++)
        //printf("%c",*(s.ch+i));
        cout<<s.ch[i];
}

int main()
{
    HString s1,s2,Sub,s,T;
    int pos,len;
    char chars1[10],chars2[10];
    cout << "请给s1赋值：" << endl;
    cin>>chars1;
    StrAssign(s1,chars1);
    cout << "请给s2赋值：" << endl;
    cin>>chars2;
    StrAssign(s2,chars2);
    cout << "赋值成功！s1为：" << endl;
    Print(s1);
    printf("\n");
    cout << "赋值成功！s2为：" << endl;
    Print(s2);
     printf("\n");
    cout << "s1和s2连接而成的新串T为：" << endl;
    Concat(T,s1,s2);
    Print(T);
     printf("\n");

    cout << "请输入需要返回子串Sub在主串T中的第pos个字符和长度len为多少?" << endl;
    scanf("%d",&pos);
    scanf("%d",&len);

    SubString(Sub,T,pos,len);
    Print(Sub);
    printf("\n");
    pos=Index(T,Sub,0);
    printf("子串在主串的第%d个字符之后的位置",pos);
    return 0;
}