关于KMP算法问题 跪求大神

Question

#include
#include
#define MAXSIZE 20
char *String_Create()
{
char *s,ch;
int i=0;
s=(char *)malloc(sizeof(MAXSIZE));
ch=getchar();
while(ch!='\n')
{
*(s+i)=ch;
i++;
ch=getchar();
}
return s;
}
int String_Length(char *s)
{
int l=0;
while(*s!='\0')
{
l++;
s++;
}
return l;
}
int String_IndexKMP(char *d,char *s,int pos)
{
int i=pos,j=1,ld,ls;
ld=String_Length(d);
ls=String_Length(s);

int k=1,next[20],l=0;
next[1]=0;
while(k<ls)
{
    if(l==0||(s+k)==(s+l))
    {
        ++k;
        ++l;
        if((s+k)!=(s+l))
        next[k]=l;
        else
        next[k]=next[l];
     }
     else
     l=next[l];
 }

while(i<=ld&&j<=ls)
{
    if(j==0||(ld+i)==(ls+j))
    {
        ++i;
        ++j;
     }

     else
    j=next[j];
 }
 if(j>ls)
 return (i-ls);
 else
 return 0;

}
void String_Show(char *s)
{
while(putchar(*s++));
printf("\n");
}
int main()
{
char *str,*c;
int ans;
c=(char *)malloc(sizeof(MAXSIZE));
printf("请输入主串:");
str=String_Create();
printf("请输入子串:");
gets(c);
ans=String_IndexKMP(str,c,1);
printf("子串在主串中的位置为:%d",ans);
return 0;
}

Answer 1

http://blog.163.com/gene_lu/blog/static/640254212011111334214331/