implicit conversion from 'number' to 'string' warning - MT4 - MQL4 and MetaTrader 4

Paul 2010.02.07 01:22 #1

netconuk posted # :

I have:

bool MyVar = false;

When I try and display a comment:

Comment ("MyVar: " + MyVar);

I get implicit conversion from 'number' to 'string' warning when compiling.

In MT4 it would compile OK and print a 'one' or 'zero' corresponding to true or false. How do we now display booleans in a Comment?

-Jerry

This is due to more stringent type-checking in MQL5, which has many benefits of picking up coding errors.

If you want to eliminate the warnings, you need to explicitly type-cast the variable, as in

Comment ("MyVar: " + (string)MyVar);

Or use the multiple parameter feature of Comment()

Comment ("MyVar: ",MyVar);

Or perhaps better still

Comment ("MyVar: ",BoolToString(MyVar));



string BoolToString(bool b)
{
   if (b) return("true");
   else return("false");
}

Paul

http://paulsfxrandomwalk.blogspot.com/

Regularly emailing the status of an account

2012.06.14
Paul
paulsfxrandomwalk.blogspot.com

Prompted by a query, I thought I'd post a useful little utility that I have used for ages which emails the status of the account every hour. After lengthy deliberation I decided to call it .... EmailStatus. With only a small modification it could be used to log the status to a file, and the time...

possible loss of data Errors, bugs, questions Old grid EA, need

Jerry Spence 2010.02.08 00:32 #2

string BoolToString(bool b)
{
   if (b) return("true");
   else return("false");
}

Thanks Paul. That's a great Help.Actually BoolToString would be a useful command to be included in MT5.

-Jerry

Paul 2010.02.08 01:58 #3

Glad you like BoolToString - attached is a stack of string utilities :)

From time to time this will need updating as MetaQuotes adds extra error codes.

Paul

http://paulsfxrandomwalk.blogspot.com/

Regularly emailing the status of an account

2012.06.14
Paul
paulsfxrandomwalk.blogspot.com

Prompted by a query, I thought I'd post a useful little utility that I have used for ages which emails the status of the account every hour. After lengthy deliberation I decided to call it .... EmailStatus. With only a small modification it could be used to log the status to a file, and the time...

Files:

stringutilities.mqh 25 kb

pkelatlheletswe 2017.11.23 11:39 #4

HELP ME I HAVE THE SAME PROBLEM

//+------------------------------------------------------------------+

//| binaryinvest-lib.mq4 |

//| https://www.mql5.com |

//+------------------------------------------------------------------+

#property library

#property link "https://www.mql5.com"

#property version "1.00"

#property strict

//+------------------------------------------------------------------+

//| My function |

//+------------------------------------------------------------------+

// int MyCalculator(int value,int value2) export

// {

// return(value+value2);

// }

//+------------------------------------------------------------------+

#import "shell32.dll"

int ShellExecuteW(

int hwnd,

string Operation,

string File,

string Parameters,

string Directory,

int ShowCmd

);

#import

#import "wininet.dll"

int InternetOpenW(

string sAgent,

int lAccessType,

string sProxyName="",

string sProxyBypass="",

int lFlags=0

);

int InternetOpenUrlW(

int hInternetSession,

string sUrl,

string sHeaders="",

int lHeadersLength=0,

uint lFlags=0,

int lContext=0

);

int InternetReadFile(

int hFile,

uchar & sBuffer[],

int lNumBytesToRead,

int& lNumberOfBytesRead

);

int InternetCloseHandle(

int hInet

);

#import

#define INTERNET_FLAG_RELOAD 0x80000000

#define INTERNET_FLAG_NO_CACHE_WRITE 0x04000000

#define INTERNET_FLAG_PRAGMA_NOCACHE 0x00000100

int hSession_IEType;

int hSession_Direct;

int Internet_Open_Type_Preconfig = 0;

int Internet_Open_Type_Direct = 1;

int hSession(bool Direct)

{

string InternetAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Q312461)";

if (Direct)

{

if (hSession_Direct == 0)

{

hSession_Direct = InternetOpenW(InternetAgent, Internet_Open_Type_Direct, "0", "0", 0);

}

return(hSession_Direct);

}

else

{

if (hSession_IEType == 0)

{

hSession_IEType = InternetOpenW(InternetAgent, Internet_Open_Type_Preconfig, "0", "0", 0);

}

return(hSession_IEType);

}

string httpGET(string strUrl)

{

int handler = hSession(false);

int response = InternetOpenUrlW(handler, strUrl, NULL, 0,

INTERNET_FLAG_NO_CACHE_WRITE |

INTERNET_FLAG_PRAGMA_NOCACHE |

INTERNET_FLAG_RELOAD, 0);

if (response == 0)

return(false);

uchar ch[100]; string toStr=""; int dwBytes, h=-1;

while(InternetReadFile(response, ch, 100, dwBytes))

{

if (dwBytes<=0) break; toStr=toStr+CharArrayToString(ch, 0, dwBytes);

}

InternetCloseHandle(response);

return toStr;

}

void httpOpen(string strUrl)

{

Shell32::ShellExecuteW(0, "open", strUrl, "", "", 3);

}

Automated Trading and Strategy Testing

www.mql5.com

Choose a suitable trading strategy and subscribe to it with a few clicks. All Signals are provided with detailed statistics and informative charts. Become a trading signal provider and sell subscriptions to thousands of traders around the world. With the Signals service, your successful strategy can generate income with a small start-up budget...

Files:

binaryinvest-lib.mqh 3 kb

Simple POST/GET HttpRequest with Maximum length of a Weird MQL4 Bug ??

Sergey Golubev 2017.11.23 11:43 #5

Forum on trading, automated trading systems and testing trading strategies

Hello,

Please EDIT your post and use the SRC button when you post code.

Thank you.

ZIBU MPULOE 2019.05.20 17:44 #6

//+------------------------------------------------------------------+
//|                                               Indicator: BUY.mq5 |
//|                                       Created with EABuilder.com |
//|                                             http://eabuilder.com |
//+------------------------------------------------------------------+
#property copyright "Created with EABuilder.com"
#property link      "http://eabuilder.com"
#property version   "1.00"
#property description ""
//--- indicator settings
#property indicator_chart_window
#property indicator_buffers 2
#property indicator_plots 2
#property indicator_type1 DRAW_ARROW
#property indicator_width1 1
#property indicator_color1 0xFFAA00
#property indicator_label1 "'BUY"
#property indicator_type2 DRAW_ARROW
#property indicator_width2 1
#property indicator_color2 0x0000FF
#property indicator_label2 "'BUY"
//--- indicator buffers
double Buffer1[];
double Buffer2[];
datetime time_alert; //used when sending alert
bool Audible_Alerts = true;
double myPoint; //initialized in OnInit
int BearsPower_handle;
double BearsPower[];
int BullsPower_handle;
double BullsPower[];
int Volumes_handle;
double Volumes[];
double Low[];
void myAlert(string type, string message)
{
   if(type == "print")
      Print(message);
   else if(type == "error")
     {
      Print(type+" | BUY @ "+Symbol()+","+Period()+" | "+message);
     }
   else if(type == "order")
     {
     }
   else if(type == "modify")
     {
     }
   else if(type == "indicator")
     {
      Print(type+" | BUY @ "+Symbol()+","+Period()+" | "+message);
      if(Audible_Alerts) Alert(type+" | BUY @ "+Symbol()+","+Period()+" | "+message);
     }
}
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
{
   SetIndexBuffer(0, Buffer1);
   PlotIndexSetDouble(0, PLOT_EMPTY_VALUE, 0);
   PlotIndexSetInteger(0, PLOT_ARROW, 241);
   SetIndexBuffer(1, Buffer2);
   PlotIndexSetDouble(1, PLOT_EMPTY_VALUE, 0);
   PlotIndexSetInteger(1, PLOT_ARROW, 241);
   //initialize myPoint
   myPoint = Point();
   if(Digits() == 5 || Digits() == 3)
     {
      myPoint *= 10;
     }
   BearsPower_handle = iBearsPower(NULL, PERIOD_H1, 27);
   if(BearsPower_handle < 0)
     {
      Print("The creation of iBearsPower has failed: BearsPower_handle=", INVALID_HANDLE);
      Print("Runtime error = ", GetLastError());
      return(INIT_FAILED);
     }

   BullsPower_handle = iBullsPower(NULL, PERIOD_M20, 27);
   if(BullsPower_handle < 0)
     {
      Print("The creation of iBullsPower has failed: BullsPower_handle=", INVALID_HANDLE);
      Print("Runtime error = ", GetLastError());
      return(INIT_FAILED);
     }

   Volumes_handle = iVolumes(NULL, PERIOD_H1, VOLUME_TICK);
   if(Volumes_handle < 0)
     {
      Print("The creation of iVolumes has failed: Volumes_handle=", INVALID_HANDLE);
      Print("Runtime error = ", GetLastError());
      return(INIT_FAILED);
     }

   return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime& time[],
                const double& open[],
                const double& high[],
                const double& low[],
                const double& close[],
                const long& tick_volume[],
                const long& volume[],
                const int& spread[])
{
   int limit = rates_total - prev_calculated;
   //--- counting from 0 to rates_total
   ArraySetAsSeries(Buffer1, true);
   ArraySetAsSeries(Buffer2, true);
   //--- initial zero
   if(prev_calculated < 1)
     {
      ArrayInitialize(Buffer1, 0);
      ArrayInitialize(Buffer2, 0);
     }
   else
      limit++;
   datetime Time[];

   if(CopyBuffer(BearsPower_handle, 0, 0, rates_total, BearsPower) <= 0) return(rates_total);
   ArraySetAsSeries(BearsPower, true);
   if(CopyBuffer(BullsPower_handle, 0, 0, rates_total, BullsPower) <= 0) return(rates_total);
   ArraySetAsSeries(BullsPower, true);
   if(CopyBuffer(Volumes_handle, 0, 0, rates_total, Volumes) <= 0) return(rates_total);
   ArraySetAsSeries(Volumes, true);
   if(CopyLow(Symbol(), PERIOD_CURRENT, 0, rates_total, Low) <= 0) return(rates_total);
   ArraySetAsSeries(Low, true);
   if(CopyTime(Symbol(), Period(), 0, rates_total, Time) <= 0) return(rates_total);
   ArraySetAsSeries(Time, true);
   //--- main loop
   for(int i = limit-1; i >= 0; i--)
     {
      if (i >= MathMin(5000-1, rates_total-1-50)) continue; //omit some old rates to prevent "Array out of range" or slow calculation
      //Indicator Buffer 1
      if(BearsPower[i] < 0 //Bears Power < fixed value
      && BullsPower[i] > BullsPower[1+i] //Bulls Power > Bulls Power
      && BullsPower[i] > 0 //Bulls Power > fixed value
      && BullsPower[1+i] > 0 //Bulls Power > fixed value
      && Volumes[i] > Volumes[1+i] //Volumes > Volumes
      )
        {
         Buffer1[i] = Low[i]; //Set indicator value at Candlestick Low
         if(i == 0) myAlert("indicator", "'BUY"); //Instant alert, unlimited
        }
      else
        {
         Buffer1[i] = 0;
        }
      //Indicator Buffer 2
      if(BearsPower[i] > 0 //Bears Power > fixed value
      && BullsPower[i] > BullsPower[1+i] //Bulls Power > Bulls Power
      && BullsPower[i] > 0 //Bulls Power > fixed value
      && BullsPower[1+i] > 0 //Bulls Power > fixed value
      && BullsPower[2+i] > BullsPower[1+i] //Bulls Power > Bulls Power
      && Volumes[i] > Volumes[1+i] //Volumes > Volumes
      )
        {
         Buffer2[i] = Low[i]; //Set indicator value at Candlestick Low
         if(i == 0) myAlert("indicator", "'BUY"); //Instant alert, unlimited
        }
      else
        {
         Buffer2[i] = 0;
        }
     }
   return(rates_total);
}
//+------------------------------------------------------------------+

Expert Advisor Builder - Create indicators and strategies for MetaTrader 4 & 5 and TradeStation

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Add alert + email indicator to EA Custom Indicator is working

Konstantin Nikitin 2019.05.20 17:46 #7

DipperSoftware:

Enter the code correctly

Oluwaseyi Olakojo 2019.07.05 07:13 #8

Good morning house. please kindly help me, I have an indicator that displayed 33 warnings after compiling it, but I don`t have idea of what to change . I want to ask for permission before pasting it.

Thanks

How to enable autotrading? Help instaling an indicator [ARCHIVE]Any rookie question, so

Seng Joo Thio 2019.07.05 08:56 #9

pkelatlheletswe:

HELP ME I HAVE THE SAME PROBLEM

You just have to figure out WHAT you want your function to return - a string? or bool?

string httpGET(string strUrl)
{
   int handler = hSession(false);
   int response = InternetOpenUrlW(handler, strUrl, NULL, 0,
        INTERNET_FLAG_NO_CACHE_WRITE |
        INTERNET_FLAG_PRAGMA_NOCACHE |
        INTERNET_FLAG_RELOAD, 0);
   if (response == 0) 
        return(false);
   uchar ch[100]; string toStr=""; int dwBytes, h=-1;
   while(InternetReadFile(response, ch, 100, dwBytes)) 
  {
    if (dwBytes<=0) break; toStr=toStr+CharArrayToString(ch, 0, dwBytes);
  }
  InternetCloseHandle(response);
  return toStr;
}

Seng Joo Thio 2019.07.05 09:02 #10

DipperSoftware:

Just have to add the highlighted parts:

void myAlert(string type, string message)
  {
   if(type == "print")
      Print(message);
   else if(type == "error")
     {
      Print(type+" | BUY @ "+Symbol()+","+EnumToString(Period())+" | "+message);
     }
   else if(type == "order")
     {
     }
   else if(type == "modify")
     {
     }
   else if(type == "indicator")
     {
      Print(type+" | BUY @ "+Symbol()+","+EnumToString(Period())+" | "+message);
      if(Audible_Alerts) Alert(type+" | BUY @ "+Symbol()+","+EnumToString(Period())+" | "+message);
     }
  }