KMP模板

void getnext()
{  
    int i=0;  
    int j= next[0] = -1;  
    while( i < pattern_len)
	{  
        if( j==-1 || pattern[i] == pattern[j] )
		{  
            i++; j++; 
		   if (pattern[i] != pattern[j]) 
                next[i] = j;  
            else 
                next[i] = next[j]; 
        }
		else  
            j = next[j];  
    }  
}  
int kmp()  
{  
    int i = 0, j = 0;  
    str_len = strlen(str);  
    getNext();  
    while (i < str_len && j < pattern_len)  
    {  
        if (j == -1 || str[i] == pattern[j])  
        {  
            ++i;  
            ++j;  
        }  
        else  
            j = next[j];  
    }  
    if (j >= pattern_len)  
        return i - pattern_len;  
    else  
        return -1;  
}