What does “warning: not all control paths return a value” mean? | Forex Factory

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What does “warning: not all control paths return a value” mean?

  • #1
  • First Post: Mar 30, 2021 3:45pm Mar 30, 2021 3:45pm
as I received this error after compiling



Inserted Code
int TradeEntry(int Type){
  
   if(Type == 0){
  
      double BTP = Ask + (TakeProfit *Point);
      double BSL = Ask - (StopLoss *Point);
        
        if(OrderSend(Symbol(),OP_BUY,0.1,Ask,10,BSL,BTP,NULL,0,0,clrBlue)){
        return true;}
      
         else{return false;}
   }
   if(Type ==1){
      double STP = Bid - (TakeProfit *Point);
      double SSL = Bid + (StopLoss *Point);
      
       if(OrderSend(Symbol(),OP_SELL,0.1,Bid,10,SSL,STP,NULL,0,0,clrRed)){
       return true;}
      
       else{return false;}
  
   }
}
  • #2
  • Mar 30, 2021 3:55pm Mar 30, 2021 3:55pm
It's asking you what to do if (Type==3)......or any value other than 0 or 1........you may know 0 or 1 as buy or sell and know that it will never execute the function with something other than 0 or 1 but the function doesn't know this. Place a return(false) just before the last closing bracket as a catchall.
  • #3
  • Mar 30, 2021 5:26pm Mar 30, 2021 5:26pm
it compiled correctly when I did as you said, I understood that it was expecting to state the condition for the rest of value of type. but what I can not understand that the return false although I did not mention when it will be false

Inserted Code
bool TradeEntry (int Type){
      if(Type ==0){
      double BTP = Ask + (TakeProfit *Point);
      double BSL = Ask - (StopLoss *Point);
      int Buy = OrderSend(Symbol(),OP_BUY,Volum_,Ask,10,BSL,BTP,NULL,0,0,clrBlue);}
      
      if(Type == 1){
      double STP = Bid - (TakeProfit *Point);
      double SSL = Bid + (StopLoss *Point);
      int Sell = OrderSend(Symbol(),OP_SELL,Volum_,Bid,10,SSL,STP,NULL,0,0,clrRed);}
return false;
}
  • #4
  • Mar 30, 2021 10:41pm Mar 30, 2021 10:41pm
Inserted Code
bool TradeEntry(int Type)
   {
    if(Type == 0)
       {
         double BTP = Ask + (TakeProfit *Point);
         double BSL = Ask - (StopLoss *Point);
          if(OrderSend(Symbol(),OP_BUY,0.1,Ask,10,BSL,BTP,NULL,0,0,clrBlue))
             {
               return true;
             }
          else
            {
              return false;
            }
        }
   if(Type ==1)
         {
            double STP = Bid - (TakeProfit *Point);
            double SSL = Bid + (StopLoss *Point);
            if(OrderSend(Symbol(),OP_SELL,0.1,Bid,10,SSL,STP,NULL,0,0,clrRed))
               {
                 return true;
               }
            else
             {
              return false;
              }
      }
   return(false);//only add this line don't remove the earlier return statements
 
}

Note that when you create the function, the function type must match the return type. You can get away with it because MQL4 is very forgiving with type casting but it is bad practice to mismatch types. Accordingly you will see the first line if now bool TradeEntry(int Type). Alternatively you could return the ticket number which would have been an int.
  • #5
  • Edited 11:23am Apr 2, 2021 7:03am | Edited 11:23am
Thank you for your advice,
There is one more thing I need your help with to understand if you do not mind
I had a problem with the EA that when I used the function created, the EA would execute only the buy orders and for the sell order it sends to the journal the note that I mention in else, for sell execution, but after I deleted the below underlined 2 lines it executed both sell and buy order. I just need your help to understand :
*how the system read the code although it has been compiled correctly, how the system understood my code as to execute only the buy orders
*and why it sent the Print of "else" of sell order not the buy




-------------------------------------
// Below is the function code//
------------------------------------

Inserted Code
int TradeEntry(int Type){
  
   if(Type == 0){
  
      double BTP = Ask + (TakeProfit *Point);
      double BSL = Ask - (StopLoss *Point);
        
        if(OrderSend(Symbol(),OP_BUY,0.1,Ask,10,BSL,BTP,NULL,0,0,clrBlue)){
        return true;}
      
         else{return false;}                                                 //this line I delete then it executed the selling trades[/u][/u]
   }
   if(Type ==1){
      double STP = Bid - (TakeProfit *Point);
      double SSL = Bid + (StopLoss *Point);
      
       if(OrderSend(Symbol(),OP_SELL,0.1,Bid,10,SSL,STP,NULL,0,0,clrRed)){
       return true;}
      
       else{return false;}                               //this line I delete then it executed the selling trades[/u][/u]
  
   }
   return false;
}

-----------------------------------------------------
//Below is the Ontick section//

----------------------------------------------------

Inserted Code
void OnTick()
  {
double value = MathRand();
double remain = MathMod(value,2);
 
double MdValue = iMA(Symbol(),0,MA_Period,Shift,MA_Method,AplliedPrice,1);
double SARValue = iSAR(Symbol(),0,Step,Maximum,0);
 
if(remain == 0 && Ask>MdValue && OrdersTotal()==0){
        if (TradeEntry(0)){
         Print("buy Trade Sent successfully");
       }
          else{
          Print("Buy order sending failed");
       }
      
      
         }
 
    
if(remain==1&& Bid< MdValue && OrdersTotal()==0){
       if (TradeEntry(1)){
         Print("Sell Trade Sent successfully");
       }
          else{
          Print("SELL Order Sending failed");
       }
      
      
         }
   }

only when I deleted the above underlined 2 lines of else it executed sell and buy
Attached Image(s) (click to enlarge)
Click to Enlarge Name: 2da56797bd870bec9241351820b8f1b3.png Size: 53 KB
Click to Enlarge Name: Chart.PNG Size: 32 KB
Click to Enlarge Name: Sell.PNG Size: 23 KB
  • #6
  • Apr 2, 2021 12:02pm Apr 2, 2021 12:02pm
I haven't analyzed in depth. Debugging is always a process of elimination.

In order to debug effectively, you should use lots of print statements, rather than just trying to deduce what is happening.

As an example, this line of code :-

Quote
if(OrderSend(Symbol(),OP_SELL,0.1,Bid,10,SSL,STP,NULL,0,0,clrRed)){

is wrong. OrderSend does not return a boolean(true or false). It returns a ticket number or a -1 if it fails. As I said before, MQL is very forgiving and will try help by forcing this to a boolean type but in the process induces a logic error. When MQL casts this ticket number or -1 to a boolean, it will always be true because false = 0 and true = 1 - it converts anything except 0 to 1, so trade error(-1) becomes 1, or ticket number 2653466745 becomes 1 therefore your trade result is always true irrespective of what really happened.

A better way to write this is

Quote
int ticket = OrderSend(Symbol(),OP_SELL,0.1,Bid,10,SSL,STP,NULL,0,0,clrRed)

Then you can inspect the ticket number and as long as it is greater than -1 then no problem

Quote
if(ticket>-1) Print("Great. No buy trade error");
else Print("Oh dear. Buy trade error - error = " + GetLastError());

So to go back to your code, it might compile but I would suggest there is a logic bomb there somewhere. When your sell trade comes back as failed, you have no idea if the trade failed, or if there is a problem with the program flow because you have not inspected the result of your trade where it happens.
  • #7
  • Last Post: Edited 4:44pm Apr 2, 2021 2:52pm | Edited 4:44pm
Quoting kennyhubbard
In order to debug effectively, you should use lots of print statements, rather than just trying to deduce what is happening.
I did not know how to do it as the problem turned out to be in the code of the function that I was trying to create and the problem is sorted out by deleting these 2 line in my code of the function else{return false;} in both conditions if (type ==0) and if ( type ==1) and now the EA is executing the sell and buy.
but I did not understand the logic of the solution and I was just trying to understand how this line (else{return false;} ) affected the code that way that made it execute only the buy orders and why as well it send the note of Print("SELL Order Sending failed") and not the note of Print("Buy order sending failed") ,

thanks for your help
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