Using StringConcatenate in MT5

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Hi

I'm having issues with using StringConcatenate within MT5. I am converting MT4 code to MT5 and have come across something that I would of thought would be simple - but after several attempts at solving it - seems to be a bit of an issue for me.

I have a bit of code that creates a string and then sends that off as a notification. SendNotification likes a straight string - nothing fancy.

MetaTrader 4 that works fine - 

     string sendInformation = StringConcatenate("Account balance = $",AccountBalance()," and Equity = $",AccountEquity());
     SendNotification(sendInformation);

  

MetaTrader 5 that does not work

     string CurrentAccountBalance = DoubleToString(AccountInfoDouble(ACCOUNT_BALANCE));
     string textString = "Account balance = $";
     string sendInformation = StringConcatenate(textString,CurrentAccountBalance);
     SendNotification(sendInformation);


The error I get is - 

'StringConcatenate' - wrong parameters count

implicit conversion from 'number' to 'string'


I'm not smart enough to know why a method designed to join two strings together returns an integer.

Does anyone have an example of the use of the StringConcatenate method within MT5 - or point me in the direction of some code. All the examples I can find are MT4.


Thanks

 

StringConcatenate works differently in MQL5 than in MQL4.

In MQL4, it returns the string formed by concatenation.

In MQL5, the first string variable you insert is what is used to form the concatenation with the other two (or more) string values you put as arguments.

string a = "Hello ";
string b = "World";
string c;

StringConcatenate(c, a, b);

Print(c); // Hello World

MQL5 Docs -> StringConcatenate: https://www.mql5.com/en/docs/strings/stringconcatenate

IMO it was a mistake to by the devs to change it because it breaks code and things like that are part of the reason why MQL5 wasn't received well by the community when it was first released.

One way to make your code compatible between MQL4 and MQL5 is to use an #ifdef statement

string sendInformation;

#ifdef __MQL4__
  sendInformation = StringConcatenate(textString,CurrentAccountBalance);
#else
  StringConcatenate(sendInformation, textString, CurrentAccountBalance);
#endif
Documentation on MQL5: String Functions / StringConcatenate
Documentation on MQL5: String Functions / StringConcatenate
  • www.mql5.com
StringConcatenate - String Functions - MQL5 Reference - Reference on algorithmic/automated trading language for MetaTrader 5
 

Corrected version working with mt5 : 

     string CurrentAccountBalance = DoubleToString(AccountInfoDouble(ACCOUNT_BALANCE));
     string textString = "Account balance = $";

     string sendInformation;
     StringConcatenate(sendInformation,textString,CurrentAccountBalance);
     SendNotification(sendInformation);
 
Alexander Martinez #:

StringConcatenate works differently in MQL5 than in MQL4.

In MQL4, it returns the string formed by concatenation.

In MQL5, the first string variable you insert is what is used to form the concatenation with the other two (or more) string values you put as arguments.


MQL5 Docs -> StringConcatenate: https://www.mql5.com/en/docs/strings/stringconcatenate

IMO it was a mistake to by the devs to change it because it breaks code and things like that are part of the reason why MQL5 wasn't received well by the community when it was first released.

One way to make your code compatible between MQL4 and MQL5 is to use an #ifdef statement

Hi Alexander

Thank you for your example - it now makes perfect sense. Your example (hello world) should be posted into the documentation - very clear.

And yes I do agree with you that the implementation of MQL5 is foreign to other operating system upgrades. Usually each revision builds on the previous versions - it does not replace or re-write methods and force the developer to re-learn.

Thanks again.

 
Noe Combes Bardoll #:

Corrected version working with mt5 :

Hi Noe

Thank you - yes I can see how that works now.

Thanks again

 
ComputerSange:

Hi

I'm having issues with using StringConcatenate within MT5. I am converting MT4 code to MT5 and have come across something that I would of thought would be simple - but after several attempts at solving it - seems to be a bit of an issue for me.

I have a bit of code that creates a string and then sends that off as a notification. SendNotification likes a straight string - nothing fancy.

MetaTrader 4 that works fine - 


MetaTrader 5 that does not work


The error I get is - 

'StringConcatenate' - wrong parameters count

implicit conversion from 'number' to 'string'


I'm not smart enough to know why a method designed to join two strings together returns an integer.

Does anyone have an example of the use of the StringConcatenate method within MT5 - or point me in the direction of some code. All the examples I can find are MT4.


Thanks

Put 

(str)

In front any function working with number that you want to output as a string in the stringcon ... function

That is

string CurrentAccountBalance = (str)DoubleToString(AccountInfoDouble(ACCOUNT_BALANCE));
 
ComputerSange #:

Hi Alexander

Thank you for your example - it now makes perfect sense. Your example (hello world) should be posted into the documentation - very clear.

And yes I do agree with you that the implementation of MQL5 is foreign to other operating system upgrades. Usually each revision builds on the previous versions - it does not replace or re-write methods and force the developer to re-learn.

Thanks again.

lol glad it could help and let's hope they don't make the same mistake in the future. 👍
  
string a = "Hello ";
string b = "World";
string c = a + b; // StringConcatenate(c, a, b);

Print(c); // Hello World
 
Thank-god Avwerosuoghene Odukudu #:

Put 

In front any function working with number that you want to output as a string in the stringcon ... function

That is

Good to know - thanks for sharing

 
fxsaber #:

I had know idea that you could do that with strings - thanks for sharing

 
Thank-god Avwerosuoghene Odukudu #:

Put 

In front any function working with number that you want to output as a string in the stringcon ... function

That is


When I add this line into my MT5 - 

string CurrentAccountBalance = (str)DoubleToString(AccountInfoDouble(ACCOUNT_BALANCE));

 I get the following error

'str' - undeclared identifier

'DoubleToString' - some operator expected


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