Help please
- if( 2+2 == 4 ) becomes if( 4 == 4 ) becomes if( true ). if( 2+2 == 5 ) becomes if( 4 == 5 ) becomes if( false ). While(condition) means while(true). The only differences is while(condition) condition will eventually become false and the loop will terminate, while (true) is an infinite loop and must be terminated by another method (break or return) within the loop.
- () are parentheses. {} are curly braces. and [] are square brackets. All three are used in mql4. I don't know what you're questioning.
- if( 2+2 == 4 ) becomes if( 4 == 4 ) becomes if( true ). if( 2+2 == 5 ) becomes if( 4 == 5 ) becomes if( false ). While(condition) means while(true). The only differences is while(condition) condition will eventually become false and the loop will terminate, while (true) is an infinite loop and must be terminated by another method (break or return) within the loop.
- () are parentheses. {} are curly braces. and [] are square brackets. All three are used in mql4. I don't know what you're questioning.
Thank you WhRoeder.
Please ignore my 2nd question. The last bracket matched with an earlier bracket in the line.
My 1st question came from reading the code below which is an extract from the book.
Can you please tell me what does the "while (true )" depend on in this case.
Regards
Bert5
int start() // Special function 'start'
{ string Symb=Symbol(); // Symbol double Dist=1000000.0; // Presetting int Real_Order=-1; // No market orders yet double Win_Price=WindowPriceOnDropped(); // The script is dropped here //-------------------------------------------------------------------------------- 2 -- for(int i=1; i<=OrdersTotal(); i++) // Order searching cycle { if (OrderSelect(i-1,SELECT_BY_POS)==true) // If the next is available { // Order analysis: //----------------------------------------------------------------------- 3 -- if (OrderSymbol()!= Symb) continue; // Symbol is not ours int Tip=OrderType(); // Order type if (Tip>1) continue; // Pending order //----------------------------------------------------------------------- 4 -- double Price=OrderOpenPrice(); // Order price if (NormalizeDouble(MathAbs(Price-Win_Price),Digits)< //Selection NormalizeDouble(Dist,Digits)) // of the closest order { Dist=MathAbs(Price-Win_Price); // New value Real_Order=Tip; // Market order available int Ticket=OrderTicket(); // Order ticket double Lot=OrderLots(); // Amount of lots } //----------------------------------------------------------------------- 5 -- } //End of order analysis } //End of order searching //-------------------------------------------------------------------------------- 6 -- while(true) // Order closing cycle { if (Real_Order==-1) // If no market orders available { Alert("For ",Symb," no market orders available"); break; // Exit closing cycle }
You did not post enough of the while loop.
It seems, it is a loop to close orders and as soon as all orders are closed, Real_Order is set to -1. Once in that if condition, it 'breaks' the while(true) loop with break.
while(true) does run forever until you leave the loop with the break instruction.
You did not post enough of the while loop.
It seems, it is a loop to close orders and as soon as all orders are closed, Real_Order is set to -1. Once in that if condition, it 'breaks' the while(true) loop with break.
while(true) does run forever until you leave the loop with the break instruction.
Thank you Kronin,
I am posting the complete code from the book.
I just need to know exactly the condition "while(true)" is referring to.
regards
Bert5
int start() // Special function 'start'
{ string Symb=Symbol(); // Symbol double Dist=1000000.0; // Presetting int Real_Order=-1; // No market orders yet double Win_Price=WindowPriceOnDropped(); // The script is dropped here //-------------------------------------------------------------------------------- 2 -- for(int i=1; i<=OrdersTotal(); i++) // Order searching cycle { if (OrderSelect(i-1,SELECT_BY_POS)==true) // If the next is available { // Order analysis: //----------------------------------------------------------------------- 3 -- if (OrderSymbol()!= Symb) continue; // Symbol is not ours int Tip=OrderType(); // Order type if (Tip>1) continue; // Pending order //----------------------------------------------------------------------- 4 -- double Price=OrderOpenPrice(); // Order price if (NormalizeDouble(MathAbs(Price-Win_Price),Digits)< //Selection NormalizeDouble(Dist,Digits)) // of the closest order { Dist=MathAbs(Price-Win_Price); // New value Real_Order=Tip; // Market order available int Ticket=OrderTicket(); // Order ticket double Lot=OrderLots(); // Amount of lots } //----------------------------------------------------------------------- 5 -- } //End of order analysis } //End of order searching //-------------------------------------------------------------------------------- 6 -- while(true) // Order closing cycle { if (Real_Order==-1) // If no market orders available { Alert("For ",Symb," no market orders available"); break; // Exit closing cycle } //-------------------------------------------------------------------------- 7 -- switch(Real_Order) // By order type { case 0: double Price_Cls=Bid; // Order Buy string Text="Buy "; // Text for Buy break; // Из switch case 1: Price_Cls=Ask; // Order Sell Text="Sell "; // Text for Sell } Alert("Attempt to close ",Text," ",Ticket,". Awaiting response.."); bool Ans=OrderClose(Ticket,Lot,Price_Cls,2);// Order closing //-------------------------------------------------------------------------- 8 -- if (Ans==true) // Got it! :) { Alert ("Closed order ",Text," ",Ticket); break; // Exit closing cycle } //-------------------------------------------------------------------------- 9 -- int Error=GetLastError(); // Failed :( switch(Error) // Overcomable errors { case 135:Alert("The price has changed. Retrying.."); RefreshRates(); // Update data continue; // At the next iteration case 136:Alert("No prices. Waiting for a new tick.."); while(RefreshRates()==false) // To the new tick Sleep(1); // Cycle sleep continue; // At the next iteration case 146:Alert("Trading subsystem is busy. Retrying.."); Sleep(500); // Simple solution RefreshRates(); // Update data continue; // At the next iteration } switch(Error) // Critical errors { case 2 : Alert("Common error."); break; // Exit 'switch' case 5 : Alert("Old version of the client terminal."); break; // Exit 'switch' case 64: Alert("Account is blocked."); break; // Exit 'switch' case 133:Alert("Trading is prohibited"); break; // Exit 'switch' default: Alert("Occurred error ",Error);//Other alternatives } break; // Exit closing cycle } //------------------------------------------------------------------------------- 10 -- Alert ("The script has finished operations -----------------------------"); return; // Exit start() }
{
string Symb=Symbol(); // Symbol
double Dist=1000000.0; // Presetting
int Real_Order=-1; // No market orders yet
double Win_Price=WindowPriceOnDropped(); // The script is dropped here
//-------------------------------------------------------------------------------- 2 --
for(int i=1; i<=OrdersTotal(); i++) // Order searching cycle
{
if (OrderSelect(i-1,SELECT_BY_POS)==true) // If the next is available
{ // Order analysis:
//----------------------------------------------------------------------- 3 --
if (OrderSymbol()!= Symb) continue; // Symbol is not ours
int Tip=OrderType(); // Order type
if (Tip>1) continue; // Pending order
//----------------------------------------------------------------------- 4 --
double Price=OrderOpenPrice(); // Order price
if (NormalizeDouble(MathAbs(Price-Win_Price),Digits)< //Selection
NormalizeDouble(Dist,Digits)) // of the closest order
{
Dist=MathAbs(Price-Win_Price); // New value
Real_Order=Tip; // Market order available
int Ticket=OrderTicket(); // Order ticket
double Lot=OrderLots(); // Amount of lots
}
//----------------------------------------------------------------------- 5 --
} //End of order analysis
} //End of order searching
//-------------------------------------------------------------------------------- 6 --
while(true) // Order closing cycle
{
if (Real_Order==-1) // If no market orders available
{
Alert("For ",Symb," no market orders available");
break; // Exit closing cycle
}
//-------------------------------------------------------------------------- 7 --
switch(Real_Order) // By order type
{
case 0: double Price_Cls=Bid; // Order Buy
string Text="Buy "; // Text for Buy
break; // Из switch
case 1: Price_Cls=Ask; // Order Sell
Text="Sell "; // Text for Sell
}
Alert("Attempt to close ",Text," ",Ticket,". Awaiting response..");
bool Ans=OrderClose(Ticket,Lot,Price_Cls,2);// Order closing
//-------------------------------------------------------------------------- 8 --
if (Ans==true) // Got it! :)
{
Alert ("Closed order ",Text," ",Ticket);
break; // Exit closing cycle
}
//-------------------------------------------------------------------------- 9 --
int Error=GetLastError(); // Failed :(
switch(Error) // Overcomable errors
{
case 135:Alert("The price has changed. Retrying..");
RefreshRates(); // Update data
continue; // At the next iteration
case 136:Alert("No prices. Waiting for a new tick..");
while(RefreshRates()==false) // To the new tick
Sleep(1); // Cycle sleep
continue; // At the next iteration
case 146:Alert("Trading subsystem is busy. Retrying..");
Sleep(500); // Simple solution
RefreshRates(); // Update data
continue; // At the next iteration
}
switch(Error) // Critical errors
{
case 2 : Alert("Common error.");
break; // Exit 'switch'
case 5 : Alert("Old version of the client terminal.");
break; // Exit 'switch'
case 64: Alert("Account is blocked.");
break; // Exit 'switch'
case 133:Alert("Trading is prohibited");
break; // Exit 'switch'
default: Alert("Occurred error ",Error);//Other alternatives
}
break; // Exit closing cycle
}
//------------------------------------------------------------------------------- 10 --
Alert ("The script has finished operations -----------------------------");
return; // Exit start()
}before starting the loop we set real order = -1
in the loop we look to all orders to find one of the EA
if one found real order becomes > -1
if no order found when loop finished then it stays -1 and we break our while function
 Play video | Please edit your post. For large amounts of code, attach it. |
before starting the loop we set real order = -1
in the loop we look to all orders to find one of the EA
if one found real order becomes > -1
if no order found when loop finished then it stays -1 and we break our while function
Thank you deVries
I understand now. You have re shown the code with the functions colored which makes it readable. How did you do that. I copied and pasted and lost the colour.
I know WHRoeder has said that code must be inserted using the SRC button. This I will do in the future.
It is a question of getting used to the site and how to use it properly.
Thanks again.
WHRoeder,
Sorry for not doing it properly. I will use the SRC button in the future to add code.
I understand the "while(true)" now from DeVries response.
Again thank you for your help. It is very much appreciated.
Bert5
This link Play video you can see also in the post of WHRoeder you open by clicking on it
It will show you how to post a code using 'SRC' button inside a message
After the code attaching is done we can give some text background color
with using 'ab_pencil' button you can find in the same line as the 'SRC' button
This link Play video you can see also in the post of WHRoeder you open by clicking on it
It will show you how to post a code using 'SRC' button inside a message
After the code attaching is done we can give some text background color
with using 'ab_pencil' button you can find in the same line as the 'SRC' button
deVries
Much appreciated.
Thanks.
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Hi All,
I am studying the MQL4 book. I have 2 questions.
1) In some of the coding I see the "While (true)" being used. I would have thought that within the brackets the condition is stated. I would have thought "True" of itself is not a condition.
2) Mostly I see only ( ) sometimes I see ( ) ). What does the bracket in the middle signify.
These questions probably have very simple answers but I have searched and cannot find an explanation.
Please accept I am in the early stages of learning programming.
Will appreciate your help.
Regards
Bert5