Solidity,private function can't return value - ethereum

The code below can't estimate gasLimit by metamask, force send transaction failed also.
function calc(uint256 _boughtTokenAmount) private returns (uint256) {
/* uint256 _circle = safeSub(now, startTime) % circleSecs; */
uint256 _circle = 2;
if(_circle == 0){
return _boughtTokenAmount;
}else{
uint256 _d = safeMul(100 , safeSub(lastCircle, 1));
uint256 _n = safeSub(_d, safeMul(safeSub(_circle, 1), safeSub(attenuationCoefficient0 ,attenuationCoefficient)));
uint256 _ret = safeMul(_boughtTokenAmount, _n);
testRet = _ret;
_ret = _ret/_d;
testRet1 = _ret;
return uint(_ret);
}
}
If change the last line 'return uint(_ret)' to 'return _boughtTokenAmount',this code works, and variable '_d', '_n', 'testRet1' got expected value.
So my question is, how the return the variable '_ret'.
Thanks.

Related

Can I send tone() function wirelessly?

I have a simple RPM Simulator (opensource) that generates values through the tone() function.
I need to send the RPM wirelessly through an nrf24l01 to a second Arduino that uses the RPM as a shiftlight, both come from chippernut.
The tone() function only sends to the pin, trying to read the values did not work.
How can i get the value of x (RPM) after it leaves the tone function?
I have tried reading it through analogRead, digitalRead, BitRead, tried printing the value of x which stays constant, to no avail, and it updates very slowly if it reads the output pin.
This is the code:
float RPM_MIN = 2500;
float RPM_MAX = 8000;
int Accel_Rate = 20;
float pulses_per_rev = 2.0; // make sure to keep the decimal
boolean accel = false;
float x;
long previousMillis = 0;
unsigned long currentMillis=0;
//float RPM_PRINT; //my addition to get a value to print
void setup() {
Serial.begin(57600);
pinMode(5, OUTPUT);
RPM_MIN = (RPM_MIN / 60);
RPM_MAX = (RPM_MAX / 60);
x = RPM_MIN;
}
void loop() {
while (accel==false){
currentMillis = millis();
if(currentMillis - previousMillis > Accel_Rate) {
previousMillis = currentMillis;
x++;
tone(5,x*pulses_per_rev);
if (x>RPM_MAX){accel=true;}
}
}
while (accel==true){
currentMillis = millis();
if(currentMillis - previousMillis > Accel_Rate) {
previousMillis = currentMillis;
x--;
tone(5,x*pulses_per_rev);
if (x<RPM_MIN){accel=false;}
}
}
//RPM_PRINT = x*pulses_per_rev;
//RPM_PRINT = digitalRead(5);
//RPM_PRINT = analogRead(5);
//Serial.println(RPM_PRINT);
}
Expected Result is a Value between 2000-8000 that is constantly changing
actual result is 1/0 or 81,33 or 4,1 or 900-980 updating once every few seconds.
How can I solve?

What is the difference between balances[owner] and balances[plot.owner]?

I'm learning Solidity via this https://medium.com/coinmonks/ethereum-land-marketplace-dapp-tutorial-part-1-create-and-deploy-a-smart-contract-351bc0d62be2
There's a function below that I don't know the difference between balances[owner] and balances[plot.owner].
function buyPlot(uint index) public payable {
Plot storage plot = plots[index];
require(msg.sender != plot.owner && plot.forSale && msg.value >= plot.price);
if(plot.owner == 0x0) {
balances[owner] += msg.value;
}else {
balances[plot.owner] += msg.value;
}
plot.owner = msg.sender;
plot.forSale = false;
emit PlotOwnerChanged(index);
}
Does it mean, if no one owns the plot (where plot.owner == 0x0) then pay the funds to the owner of the smart contract (the creator) or first owner of the land?
Here's the entire code.
pragma solidity ^0.4.11;
contract LandContract {
address owner;
mapping (address => uint) public balances;
struct Plot {
address owner;
bool forSale;
uint price;
}
Plot[12] public plots;
event PlotOwnerChanged(
uint index
);
event PlotPriceChanged(
uint index,
uint price
);
event PlotAvailabilityChanged(
uint index,
uint price,
bool forSale
);
constructor() public {
owner = msg.sender;
plots[0].price = 4000;
plots[0].forSale = true;
plots[1].price = 4000;
plots[1].forSale = true;
plots[2].price = 4000;
plots[2].forSale = true;
plots[3].price = 4000;
plots[3].forSale = true;
plots[4].price = 4000;
plots[4].forSale = true;
plots[5].price = 4000;
plots[5].forSale = true;
plots[6].price = 4000;
plots[6].forSale = true;
plots[7].price = 4000;
plots[7].forSale = true;
plots[8].price = 4000;
plots[8].forSale = true;
plots[9].price = 4000;
plots[9].forSale = true;
plots[10].price = 4000;
plots[10].forSale = true;
plots[11].price = 4000;
plots[11].forSale = true;
}
function putPlotUpForSale(uint index, uint price) public {
Plot storage plot = plots[index];
require(msg.sender == plot.owner && price > 0);
plot.forSale = true;
plot.price = price;
emit PlotAvailabilityChanged(index, price, true);
}
function takeOffMarket(uint index) public {
Plot storage plot = plots[index];
require(msg.sender == plot.owner);
plot.forSale = false;
emit PlotAvailabilityChanged(index, plot.price, false);
}
function getPlots() public view returns(address[], bool[], uint[]) {
address[] memory addrs = new address[](12);
bool[] memory available = new bool[](12);
uint[] memory price = new uint[](12);
for (uint i = 0; i < 12; i++) {
Plot storage plot = plots[i];
addrs[i] = plot.owner;
price[i] = plot.price;
available[i] = plot.forSale;
}
return (addrs, available, price);
}
function buyPlot(uint index) public payable {
Plot storage plot = plots[index];
require(msg.sender != plot.owner && plot.forSale && msg.value >= plot.price);
if(plot.owner == 0x0) {
balances[owner] += msg.value;
}else {
balances[plot.owner] += msg.value;
}
plot.owner = msg.sender;
plot.forSale = false;
emit PlotOwnerChanged(index);
}
function withdrawFunds() public {
address payee = msg.sender;
uint payment = balances[payee];
require(payment > 0);
balances[payee] = 0;
require(payee.send(payment));
}
function destroy() payable public {
require(msg.sender == owner);
selfdestruct(owner);
}
}
Yes, plot.owner is the person who owns a plot. Whereas the owner is the person who deployed the contract. You could think of it as if any plot that has not been bought yet belongs to the owner, that is the person who deployed the contract (assuming he did not transfer the ownership to anyone else), so when you buy a property that was not previously owned by anyone then the money will go to the owner of the contract

e+ is added with string after converting from integer

After converting integer into string , at compile time string add up with e+
like in trace i am getting value 90 and in swf it is showing 9.0e+
percentage function and teamxml functions are added below.
public function getPlayerAttack(ourTeam:Boolean=true):String{
var attackArr:Array=[];
var num:int;
var total:int=0;
var _teamXML:XML;
if (ourTeam)
_teamXML=getOurTeamXml();
else
_teamXML=getOppTeamXml();
for each (var playerList:XML in _teamXML.player.(#gp!="0")){
if (playerList.#name!="TEAM"){
var attackStat:String=getStat("attack_kills",playerList);
num = int(attackStat);
if(num >= 10)
{
total += num;
attackArr.push(num);
}
}
}
var attackPer:int = getPercent(total,attackArr.length);
var mytext:String = String(attackPer);
trace(typeof mytext);
return mytext;
}
public function getPercent(att:int,made:int):int{
if (made==0)
return 0;
return Math.round((made/att)*100);
}
public function getOurTeamXml():XML{
if (homeGame)
return xml.team.(#vh=="H")[0];
else
return xml.team.(#vh=="V")[0];
}
public function getOppTeamXml():XML{
if (homeGame)
return xml.team.(#vh=="V")[0];
else
return xml.team.(#vh=="H")[0];
}

Inaccurate GPS data using Arduino and GPS/GPRS Module

For a project I´m following this tutorial on how to track the location and output the GPS data using an Arduino with this SIM908 shield. The Arduino correctly sends the GPS data to the database. However, the coordinates are all exactly the same and it seems that they have been rounded off.
For example:
Latitude: 52.216667
Longitude: 5.483333
This isn't because of the PHP script, all it does is put the data it receives in the database. My guess is that it has something to do with the conversion function convert2Degrees.
This is the code we´re running on our Arduino:
int8_t answer;
int onModulePin= 2;
char data[100];
int data_size;
char aux_str[100];
char aux;
int x = 0;
char N_S,W_E;
char url[] = "informatica-corlaer.nl";
char frame[200];
char pin[]="0000";
char apn[]="mmm.nl";
char user_name[]="";
char password[]="";
char latitude[15];
char longitude[15];
char altitude[10];
char date[16];
char time[7];
char satellites[3];
char speedOTG[10];
char course[10];
void setup(){
pinMode(onModulePin, OUTPUT);
Serial.begin(115200);
Serial.println("Starting...");
power_on();
delay(3000);
//sets the PIN code
snprintf(aux_str, sizeof(aux_str), "AT+CPIN=%s", pin);
sendATcommand(aux_str, "OK", 2000);
delay(3000);
// starts the GPS and waits for signal
while ( start_GPS() == 0);
while (sendATcommand("AT+CREG?", "+CREG: 0,1", 2000) == 0);
// sets APN , user name and password
sendATcommand("AT+SAPBR=3,1,\"Contype\",\"GPRS\"", "OK", 2000);
snprintf(aux_str, sizeof(aux_str), "AT+SAPBR=3,1,\"APN\",\"%s\"", apn);
sendATcommand(aux_str, "OK", 2000);
snprintf(aux_str, sizeof(aux_str), "AT+SAPBR=3,1,\"USER\",\"%s\"", user_name);
sendATcommand(aux_str, "OK", 2000);
snprintf(aux_str, sizeof(aux_str), "AT+SAPBR=3,1,\"PWD\",\"%s\"", password);
sendATcommand(aux_str, "OK", 2000);
// gets the GPRS bearer
while (sendATcommand("AT+SAPBR=1,1", "OK", 20000) == 0)
{
delay(5000);
}
}
void loop(){
// gets GPS data
get_GPS();
// sends GPS data to the script
send_HTTP();
delay(5000);
}
void power_on(){
uint8_t answer=0;
// checks if the module is started
answer = sendATcommand("AT", "OK", 2000);
if (answer == 0)
{
// power on pulse
digitalWrite(onModulePin,HIGH);
delay(3000);
digitalWrite(onModulePin,LOW);
// waits for an answer from the module
while(answer == 0){
// Send AT every two seconds and wait for the answer
answer = sendATcommand("AT", "OK", 2000);
}
}
}
int8_t start_GPS(){
unsigned long previous;
previous = millis();
// starts the GPS
sendATcommand("AT+CGPSPWR=1", "OK", 2000);
sendATcommand("AT+CGPSRST=0", "OK", 2000);
// waits for fix GPS
while(( (sendATcommand("AT+CGPSSTATUS?", "2D Fix", 5000) ||
sendATcommand("AT+CGPSSTATUS?", "3D Fix", 5000)) == 0 ) &&
((millis() - previous) < 90000));
if ((millis() - previous) < 90000)
{
return 1;
}
else
{
return 0;
}
}
int8_t get_GPS(){
int8_t counter, answer;
long previous;
// First get the NMEA string
// Clean the input buffer
while( Serial.available() > 0) Serial.read();
// request Basic string
sendATcommand("AT+CGPSINF=0", "AT+CGPSINF=0\r\n\r\n", 2000);
counter = 0;
answer = 0;
memset(frame, '\0', 100); // Initialize the string
previous = millis();
// this loop waits for the NMEA string
do{
if(Serial.available() != 0){
frame[counter] = Serial.read();
counter++;
// check if the desired answer is in the response of the module
if (strstr(frame, "OK") != NULL)
{
answer = 1;
}
}
// Waits for the asnwer with time out
}
while((answer == 0) && ((millis() - previous) < 2000));
frame[counter-3] = '\0';
// Parses the string
strtok(frame, ",");
strcpy(longitude,strtok(NULL, ",")); // Gets longitude
strcpy(latitude,strtok(NULL, ",")); // Gets latitude
strcpy(altitude,strtok(NULL, ".")); // Gets altitude
strtok(NULL, ",");
strcpy(date,strtok(NULL, ".")); // Gets date
strtok(NULL, ",");
strtok(NULL, ",");
strcpy(satellites,strtok(NULL, ",")); // Gets satellites
strcpy(speedOTG,strtok(NULL, ",")); // Gets speed over ground. Unit is knots.
strcpy(course,strtok(NULL, "\r")); // Gets course
convert2Degrees(latitude);
convert2Degrees(longitude);
return answer;
}
/* convert2Degrees ( input ) - performs the conversion from input
* parameters in DD°MM.mmm’ notation to DD.dddddd° notation.
*
* Sign '+' is set for positive latitudes/longitudes (North, East)
* Sign '-' is set for negative latitudes/longitudes (South, West)
*
*/
int8_t convert2Degrees(char* input){
float deg;
float minutes;
boolean neg = false;
//auxiliar variable
char aux[10];
if (input[0] == '-')
{
neg = true;
strcpy(aux, strtok(input+1, "."));
}
else
{
strcpy(aux, strtok(input, "."));
}
// convert string to integer and add it to final float variable
deg = atof(aux);
strcpy(aux, strtok(NULL, '\0'));
minutes=atof(aux);
minutes/=1000000;
if (deg < 100)
{
minutes += deg;
deg = 0;
}
else
{
minutes += int(deg) % 100;
deg = int(deg) / 100;
}
// add minutes to degrees
deg=deg+minutes/60;
if (neg == true)
{
deg*=-1.0;
}
neg = false;
if( deg < 0 ){
neg = true;
deg*=-1;
}
float numberFloat=deg;
int intPart[10];
int digit;
long newNumber=(long)numberFloat;
int size=0;
while(1){
size=size+1;
digit=newNumber%10;
newNumber=newNumber/10;
intPart[size-1]=digit;
if (newNumber==0){
break;
}
}
int index=0;
if( neg ){
index++;
input[0]='-';
}
for (int i=size-1; i >= 0; i--)
{
input[index]=intPart[i]+'0';
index++;
}
input[index]='.';
index++;
numberFloat=(numberFloat-(int)numberFloat);
for (int i=1; i<=10 ; i++)
{
numberFloat=numberFloat*10;
digit= (long)numberFloat;
numberFloat=numberFloat-digit;
input[index]=char(digit)+48;
index++;
}
input[index]='\0';
}
void send_HTTP(){
uint8_t answer=0;
// Initializes HTTP service
answer = sendATcommand("AT+HTTPINIT", "OK", 10000);
if (answer == 1)
{
// Sets CID parameter
answer = sendATcommand("AT+HTTPPARA=\"CID\",1", "OK", 5000);
if (answer == 1)
{
// Sets url
sprintf(aux_str, "AT+HTTPPARA=\"URL\",\"http://%s/vehicleLocationTransmitter.php?", url);
Serial.print(aux_str);
sprintf(frame, "vehicleID=1&latitude=%s&longitude=%s&altitude=%s&time=%s&satellites=%s",
latitude, longitude, altitude, date, satellites);
Serial.print(frame);
answer = sendATcommand("\"", "OK", 5000);
if (answer == 1)
{
// Starts GET action
answer = sendATcommand("AT+HTTPACTION=0", "+HTTPACTION:0,200", 30000);
if (answer == 1)
{
Serial.println(F("Done!"));
}
else
{
Serial.println(F("Error getting url"));
}
}
else
{
Serial.println(F("Error setting the url"));
}
}
else
{
Serial.println(F("Error setting the CID"));
}
}
else
{
Serial.println(F("Error initializating"));
}
sendATcommand("AT+HTTPTERM", "OK", 5000);
}
int8_t sendATcommand(char* ATcommand, char* expected_answer1, unsigned int timeout){
uint8_t x=0, answer=0;
char response[100];
unsigned long previous;
memset(response, '\0', 100); // Initialize the string
delay(100);
while( Serial.available() > 0) Serial.read(); // Clean the input buffer
Serial.println(ATcommand); // Send the AT command
x = 0;
previous = millis();
// this loop waits for the answer
do{
if(Serial.available() != 0){
response[x] = Serial.read();
x++;
// check if the desired answer is in the response of the module
if (strstr(response, expected_answer1) != NULL)
{
answer = 1;
}
}
// Waits for the asnwer with time out
}
while((answer == 0) && ((millis() - previous) < timeout));
return answer;
}
Write a test case for the function in doubt (convert2Degrees())
from the comment: "parameters in DD°MM.mmm’ notation to DD.dddddd°":
If you input: 52°27.123
Then the expected Output should be: 52.45205
Calculation: 52°27.123 = 52 + 27.123/60.0 =
= 52.45205
Further you should post here the value which is input to convert2Degrees()
Your use of strtok is incorrect, and the convert2degrees has major problems.
Here's something derived from NeoGPS that doesn't use the expensive (on AVRs) divide or modulo arithmetic:
//.................................................
// A special divide-by-3 function that avoids division.
// From http://www.hackersdelight.org/divcMore.pdf
static uint32_t divu3( uint32_t n )
{
uint32_t q = (n >> 2) + (n >> 4); // q = n*0.0101 (approx).
q = q + (q >> 4); // q = n*0.01010101.
q = q + (q >> 8);
q = q + (q >> 16);
uint32_t r = n - q*3; // 0 <= r <= 15.
return q + (11*r >> 5); // Returning q + r/3.
}
//------------------------------------------------------------
// Parse the NMEA "DDDMM.mmmm" format for lat and lon.
//
// returns degrees * 10^7
uint32_t parseDDMMmmmm( char *input )
{
uint8_t digits = 0;
uint8_t sixth_digit = 0;
char chr;
// Find the decimal point
while (isdigit( input[digits] ))
digits++;
// All but the last two are degrees.
uint32_t val = 0;
while (digits > 2) {
chr = *input++;
val = val*10 + (chr - '0');
digits--;
}
// convert from degrees to minutes
val *= 60;
// Add in the last 2 minutes digits
uint8_t minutes = 0;
while (digits > 0) {
chr = *input++;
minutes = minutes*10 + (chr - '0');
digits--;
}
val += minutes;
// Decimal point?
chr = *input++;
if (chr == '.') {
chr = *input++;
// Parse up to 6 digits of the fractional minutes.
while ((digits++ < 5) && isdigit( chr )) {
val = val*10 + (chr - '0');
chr = *input++;
}
if ((digits == 6) && isdigit(chr)) {
sixth_digit = chr - '0';
digits++;
}
// Scale the value up to minutes x 1000000.
while (digits < 4) {
val *= 10;
digits++;
}
}
// convert from minutes x 1000000 to degrees x 10000000.
val += divu3( val*2 + 1 ); // same as 10 * (val+30)/60 without truncation
if (digits >= 6) {
if (sixth_digit >= 9)
val += 2;
else if (sixth_digit >= 4)
val += 1;
}
return val;
} // parseDDMMmmmm
...and a floating-point version:
double parseDDMMmmmm_f( char *input )
{
uint8_t digits = 0;
char chr;
// Find the decimal point
while (isdigit( input[digits] ))
digits++;
// All but the last two are degrees.
double val = 0.0;
while (digits > 2) {
chr = *input++;
val = val*10 + (chr - '0');
digits--;
}
// convert from degrees to minutes
val *= 60;
// Add in the last 2 minutes digits
uint8_t minutes = 0;
while (digits > 0) {
chr = *input++;
minutes = minutes*10 + (chr - '0');
digits--;
}
val += minutes;
// Decimal point?
chr = *input++;
if (chr == '.') {
chr = *input++;
// Parse the fractional "mmmm" minutes.
while (isdigit( chr ) && (digits++ <= 4)) {
val = val*10 + (chr - '0');
chr = *input++;
}
// Scale the value up to minutes x 1000000.
while (digits < 4) {
val *= 10;
digits++;
}
}
// convert from minutes x 1000000 to degrees.
val *= 10.0/1000000.0 * 1.0/60.0;
return val;
} // parseDDMMmmmm_f
If you use these functions, you also need to pop the '-' off the front of your AT string, and negate the returned values:
bool south = (latitude[0] == '-');
if (south)
latitude++;
float lat = parseDDMMmmmm_f( latitude );
if (south)
lat = -lat;
convert2Degrees(longitude);
bool west = (longitude[0] == '-');
if (west)
longitude++;
float lon = parseDDMMmmmm_f( longitude );
if (west)
lon = -lon;[/code]

how to trace "depth" or stacking order of a display object?

How can you trace the "depth" or stacking order of a display object with AS3?
I'm trying to figure out if my sprite is behind another sprite...
container.getChildIndex(displayObject);
but that will only tell you how deep it is, not necessarily if anything is in front of it.
Function comparing two DisplayObject instances to determine which one is at a higher "depth" on the display list:
private function higher(a:DisplayObject, b:DisplayObject):DisplayObject
{
// Parent chains
var ac:Array = [a];
var bc:Array = [b];
// Pointers to individual nodes
var an:DisplayObject = a.parent;
var bn:DisplayObject = b.parent;
while (an != null) {
ac.push(an);
an = an.parent;
}
while (bn != null) {
bc.push(bn);
bn = bn.parent;
}
var acl:int = ac.length;
var bcl:int = bc.length;
var n:int = Math.min(acl, bcl);
var i:int = 0;
for (; i < n; i++) {
an = ac[acl - i - 1];
bn = bc[bcl - i - 1];
// First uncommon ancestor
if (an != bn)
break;
}
var ca:DisplayObjectContainer = an.parent;
if (!ca)
return null;
if (ca.getChildIndex(an) > ca.getChildIndex(bn))
return a;
else
return b;
}
Note: If one of the objects is not on the display list, the function returns null. You can change it to return the other object instead.
You can almost certainly optimize this, but this is a first cut.
Just a refactored version of Manish answer using vectors and which won't return weird result if you ever call higher(a,a.parent).
parents() may be used for other purpose too :
public function higher(a:DisplayObject, b:DisplayObject):DisplayObject
{
var aParents:Vector.<DisplayObject> = parents(a);
var bParents:Vector.<DisplayObject> = parents(b);
var commonDepth:int = Math.min(aParents.length, bParents.length);
for (var depth:int = 0; depth < commonDepth; depth++)
if (aParents[depth] != bParents[depth])
break;
if (depth == 0 || depth == commonDepth)
return null;
var commonAncestor:DisplayObjectContainer = aParents[depth].parent;
if (commonAncestor.getChildIndex(aParents[depth]) > commonAncestor.getChildIndex(bParents[depth]))
return a;
else
return b;
}
private function parents(d:DisplayObject):Vector.<DisplayObject>
{
var result:Vector.<DisplayObject> = new Vector.<DisplayObject>;
while (d != null)
{
result.unshift(d);
d = d.parent;
}
return result;
}
private function getDepth(clip:DisplayObject):uint
{
var depth:uint = 0;
var currentClip:DisplayObject = clip;
while (currentClip.parent && currentClip.parent != this)
{
depth++;
currentClip = currentClip.parent;
}
return depth;
}
container.getChildIndex(child) should do it, it returns the index of the child
This is a revised version of what jauboux did from a version Manish did.
Namely, adding a null return value from highestOf() when depths match.
/**
* #param ifDepthsMatchReturnObjectA
* #return Whichever DisplayObject is higher on the display list.
* Optionally returns `null` if they're at the same depth.
*/
public function highestOf(a:DisplayObject, b:DisplayObject, ifDepthsMatchReturnObjectA:Boolean = false):DisplayObject
{
var aParents:Vector.<DisplayObject> = ancestorsOf(a);
var bParents:Vector.<DisplayObject> = ancestorsOf(b);
var commonDepth:int = Math.min(aParents.length, bParents.length);
for (var depth:int = 0; depth < commonDepth; depth++)
if (aParents[depth] != bParents[depth])
break;
if (depth == 0 || depth == commonDepth)
return null;
var commonAncestor:DisplayObjectContainer = aParents[depth].parent;
var aDepthOnCommonAncestor:int = commonAncestor.getChildIndex(aParents[depth]);
var bDepthOnCommonAncestor:int = commonAncestor.getChildIndex(bParents[depth]);
if (aDepthOnCommonAncestor > bDepthOnCommonAncestor)
return a;
else if (aDepthOnCommonAncestor < bDepthOnCommonAncestor)
return b;
else
return ifDepthsMatchReturnObjectA ? a : null;
}
/**
* #return Whether a is higher than b.
*/
public function isHigher(a:DisplayObject, b:DisplayObject):Boolean
{
return highestOf(a, b) === a;
}
/**
* #return All ancestors of given display.
*/
private function ancestorsOf(display:DisplayObject):Vector.<DisplayObject>
{
var result:Vector.<DisplayObject> = new Vector.<DisplayObject>;
while (display != null)
{
result.unshift(display);
display = display.parent;
}
return result;
}