编辑代码

#define datatype char
#define MAXSIZE 100
#include <stdio.h>
typedef struct
{
    char ch [MAXSIZE];
    int len;
}SString;
SString StrConcat (SString s, SString t)
{
    SString s1;
    int i;
    if (s.len+t.len<=MAXSIZE)
    {
        for (i-0;i<s.len;i++)
            s1.ch[i]=s.ch[i];
        for (i=0;i<t.len;i++)
            s1.ch[s.len+i]=t.ch[i];
        s1.ch[s.len=i]='\0';
        s1.len=s.len=t.len;  
    }
    else
        s1.len=0;
    return(s1);
}

int Strcompare(SString s,SString t)
{
    int i;
    if (s.len!=t.len)
        return (0);
    else
        {
            for(i=0;i<s.len;i++)
                if (s.ch[i]!=t.ch[i])
                    return (0);
        }
    return (1);
}

int SubString (SString *sub,SString s,int pos,int len)
{

    int i;
    if (pos<0||pos>s.len||len<1||len>s.len-pos)
    {
        sub->len=0;
        return (0);
    }
    else 
    {
        for (i=0;i<len;i++)
            sub->ch[i]=s.ch[i+pos-1];
        sub->len=len;
        return (1);
    }
}

void StrInsert (SString *s,SString t, int pos)
{
    int j;
    if(s->len+t.len>=MAXSIZE||(pos>s->len+1)||(pos<1))
        printf("overflow\n");
    else
    {
        for (j=s->len;j>=pos;j--)
            s->ch[j+t.len-1]=s->ch[j-1];
        for (j=0;j<t.len;j++)
            s->ch[j+pos-1]=t.ch[j];
        s->len=s->len+t.len;
        s->ch[s->len]='\0';
    }
}

void StrDelete (SString *s,int pos ,int len)
{
    int k;
    if ((pos<1)||(pos>s->len))
        printf("error\n");
    else
        if(s->len-pos+1<len)
            s->len=pos-1;
        else
        {
            for (k=pos+len-1;k<=s->len;k++)
                s->ch[k-len]=s->ch[k];
            s->len=s->len-len;
        }
}

SString StrReplace (SString *s,SString t,int pos,int len)
{
    StrDelete (s,pos,len);
    StrInsert(s,t,pos);
}

int StrIndex(SString s,SString t)
{
    int i,j;
    i=0;
    i=0;
    while ((i<=s.len-1)&&(j<=t.len-1))
        if (s.ch[i]==t.ch[j])
        {
            i++;
            j++;
        }
        else
        {
            i=i-j+1;
            j=0;
        }
        if (j>t.len-1)
            return (i-t.len+1);
        else
            return (0);
}

int main()
{
    SString s0={"BeiJing Shanghai China",22},
        s1={"BeiJing",8},
        s2={"China",5},s,s3;
    s=StrConcat(s1,s2);
    printf("\n%s\n%d",s.ch,s.len);
    printf("\n%d\n",Strcompare(s1,s2));
    SubString(&s3,s,1,7);
    printf("\n%s\n",s3.ch);
    StrInsert(&s3,s2,8);
    printf("\n%s\n",s3.ch);
    StrDelete(&s,9,5);
    printf("\n%s\n",s.ch);
    printf("\n%d\n",StrIndex(s0,s1));

}