What does **if(!2==3)** mean in MQL exactly? I may be exposing you to my ignorance here but I'm not familiar with the logic used in that if statement.

**if(!2==3)** mean in MQL exactly? I may be exposing you to my ignorance here but I'm not familiar with the logic used in that if statement.

690

Does your array have 6 elements in it? Your loop goes from 1 to 5 indexes but array starts numeration from 0 thus if you have array of 5 elements you need to run loop from 0 to 4 --> for ( i = 0; i < 5; i ++ ) ...

And you have two things to check (line 7) while line 3 has only 1 check...

2327

What does **if(!2==3)** mean in MQL exactly?

Edit: corrected bellow.

2327

[...] but then it just freezes with the Stop button remaining active.

This happens if u enter an endless loop... 'Time' in the Tester is discrete, it only passes **between **ticks, but not **while in the same tick**. Hence, the Tester seems to be 'stuck'.

There's not enough in the code sample to see where that happens. Show us your code.

It's a valid expression, although not a very useful one. But something's not right here... The operator '!' is supposed to have higher precedence than '==' according to https://docs.mql4.com/basis/operations/rules. The integers 2 and 3 are type cast to True. So the expression should evaluate to False, but I checked it - it evaluates to True! WTF?

gordon I believe you when you say it is valid, but

I know what if(2==3) means...if 2 = 3 is true then execute the loop (but 2!=3, so the expression 2==3 is false and the if is not executed) but what does adding a ! to the front of 2==3 do to the logic tree? I don't follow.

2327

gordon I believe you when you say it is valid, but

I know what if(2==3) means...if 2 = 3 is true then execute the loop (but 2!=3, so the expression 2==3 is false and the if is not executed) but what does adding a ! to the front of 2==3 do to the logic tree? I don't follow.

I made a mistake in my last post (wasn't thinking)... There is no type casting...

The expression:

!2==3

is exactly the same as:

!(2==3)

because of precedence rules. Since '2==3' evaluates false, the whole expression evaluates True.

As to what it means... Nothing. Since 2 and 3 are constants, it basically means the 'IF' is not there... As I said - not very useful.

I made a mistake in my last post (wasn't thinking)... There is no type casting...

The expression:

!2==3

is exactly the same as:

!(2==3)

because of precedence rules. Since '2==3' evaluates false, the whole expression evaluates True.

As to what it means... Nothing. Since 2 and 3 are constants, it basically means the 'IF' is not there... As I said - not very useful.

OK, first I swear to you I have not been drinking, much, and I am not just jerking your chain here...but I can't get my mind wrapped around this.

Let's say the expression was something less specific. Instead of explicitly stated constants like 2 and 3 lets use integer variables like A and B, allowing for A and B to change value over time.

In this situation, wth does if(!A==B) mean? I know what if(A!=B) does, and I know what if(A==B) does, but what is the logic tree for an expression of the sort if(

2327

OK, first I swear to you I have not been drinking, [...]

Well, I have been drinking... (last night... woke up with a massive hangover...).

Anyway, the expression '!A==B' equals the expression '!(A==B)' which also equals the expression 'A!=B'. When I say equal, I mean equal when it comes to the expression's value for a given input, and not necessarily how that input is calculated to result in that value.

In simplistic terms, if the possible inputs are 0 and 1 only (or false and true...):

A |
B |
!A==B |
A!=B |
---|---|---|---|

0 | 0 | 0 | 0 |

1 | 0 | 1 | 1 |

0 | 1 | 1 | 1 |

1 | 1 | 0 | 0 |

gordon thank you for indulging my repetitious requests for clarification. You've made it perfectly clear now. So !A==B is the equivalent to coding A!=B in this situation.

So the "not" in front of A==B is like an XOR gate. First the valuation is performed as to whether or not A=B...and then it takes the opposite bool for the output of the expression.

If A=0 and B=0 then A==B is true, and !(A==B) become false because !(true) = not true = false = 0.

I understand now. I had not realized I could code boolean logic this way in MQL, oh the tortured schemes I've programmed to simply get to the point of logic that a simple if(!(...)) would have deftly implemented!

2327

Ya... Bottom line, u can use the '!' operator with ANY expression... And basically it negates whatever that expression evaluates to. As usual - u should either use brackets or pay attention to precedence rules when using this operator (in our case, the '!' operator has higher precedence than the '==' operator, hence no need for brackets).

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I've worked through alot with MetaTrader, but this one I really don't get. The Tester iterates a function several times - it's not that the function fails - but then it just freezes with the Stop button remaining active.

1. int MyFunction {

2. for{i=1;i<=5;i++) {

3. if(!MyArray[i]) {do something} // Comment this out and the Tester's fine; Leave it in and the Tester freezes up after several iterations.

4. if(!2==3) {do something} // Tester's fine with this without line 3 - the do something executes normally

5. } // end for

6. for{i=1;i<=5;i++) {

7. if(!MyArray[i]||AnotherArray[i]) {do something} // SAME MyArray AS LINE 3 being tested but OK if without line 3.

8. } // end for

9.} // end function

Why is one test of this array OK but not the other? In the same function. Does this make sense to anyone? Has anyone else run into this?