char* GetFilename(char *fullname)
{
    int from,to,i;
    char *newstr,*temp;
    if(fullname!=NULL)
    {
        if((temp=strchr(fullname,'.'))==NULL)//if not find dot
        newstr = fullname;
        else
        {
            from = strlen(fullname) - 1;
            to = (temp-fullname);  //the first dot's index;
            for(i=from;i--;i<=to)
            if(fullname[i]=='.')break;//find the last dot
            newstr = (char*)malloc(i+1);
            strncpy(newstr,fullname,i);
            *(newstr+i)=0;
        }
    }
    //newstr 表示带路径和名称，现在是c/data/image
    char name[50] = {""};
    char *q = strrchr(newstr,'/') + 1;  //q表示image now
    strncpy(name,q,40);
    return name;
}