#include "stdio.h"
#include "string.h"
void GetPreNext(char *s,int *next)
{
    int i,j,length;
    length=strlen(s);
    j=0;
    i=1;
    next[1]=0;
    while(i<=length)
    {
        if(j==0||s[i]==s[j])
        {
            i++;
            j++;
            if(s[i]!=s[j])
            {
                next[i]=j;
            }
            else
            {
                next[i]=next[j];
            }
        }
        else
        {
            j=next[j];
        }
    }
}
int math(char *s,char *t,int *next)
{
    int length_s,length_t;
    int i,j;
    i = 1;
    j = 1;
    length_s = strlen(s);
    length_t = strlen(t);
    if(length_s < length_t)
    {
        return -1;
    }
    else
    {
        while(i <= length_s && j <= length_t)
        {
            if(j==0||s[i]==t[j])
            {
                i++;
                j++;
            }
            else
            {
                j=next[j];
            }
        }
        if(j>length_t)
        {
            return i-j+1;
        }
        else
        {
            return -1;
        }
    }
}
void main()
{
    char s[100]="zhonghuarenminggongheguo";
    char t[100]="ing";
    int next[100]={0},n;
    GetPreNext(t,next);
    n=math(s,t,next);
    if(n==-1)
    {
        printf("Cannot find the string!\n");
    }
    else
    {
        printf("The position is %d\n",n);
    }
}
当字符串比较短的时候能查的出来，当字符串比较长的时候查不出来。请高手帮忙改下！

[ 本帖最后由 小J 于 2010-3-24 17:43 编辑 ]