Understanding an Expression

[Zarik]

Hey guys, 

can anyone please explain me what this expression means and how the (!=) condition is being evaluated? 

(m_patterns_usage&(((int)1)<<p))!=0

For more context, this code is part of a macro which is defined in the ExpertSignal.mqh after generating an Expert using a moving average as signal. 

ExpertSignal.mqh:

#define IS_PATTERN_USAGE(p)          ((m_patterns_usage&(((int)1)<<p))!=0)

my question is not about how the signal module/system is working but about the language implementation and how the syntax works in this scenario and

to be more precise:

1. What "&" symbol means? is this a logical operator or its a reference to the "m_patterns_usage" property? 
2. What does "((int)1)" means?

Thank you!

Cheers, 

Zarik

[fxsaber]

Forum on trading, automated trading systems and testing trading strategies

Understanding an Expression

Zarik, 2022.07.26 15:42

can anyone please explain me what this expression means and how the (!=) condition is being evaluated? 

(m_patterns_usage&(((int)1)<<p))!=0

Checking if the p-th bit is non-zero in the binary representation of the number m_patterns_usage.

[Fernando Carreiro]

Zarik: can anyone please explain me what this expression means and how the (!=) condition is being evaluated? For more context, this code is part of a macro which is defined in the ExpertSignal.mqh after generating an Expert using a moving average as signal. to be more precise:

1. What "&" symbol means? is this a logical operator or its a reference to the "m_patterns_usage" property? 
2. What does "((int)1)" means?

Please take the time to read the documentation and familiarise yourself with operators and expressions: Documentation on MQL5: Language Basics / Operations and Expressions

Bitwise Operations

Left Shift (<<)

The binary representation of x is shifted to the left by y digits, the freed right-side digits are filled with zeros.

Bitwise AND Operation (&)

The bitwise AND operation of binary-coded x and y representations. The value of the expression contains a 1 (TRUE) in all digits where both x and y contain non-zero, and it contains 0 (FALSE) in all other digits.

Operations of Relation

a != b; //  True if a is not equal to b                  

Boolean Operations

Logical Negation NOT (!)

Operand of the logical negation (!) must be of arithmetic type. The result is TRUE (1), if the operand value is FALSE (0); and it is equal to FALSE (0), if the operand differs from FALSE (0).

Typecasting

(int)

[Zarik]

Fernando Carreiro #:

Please take the time to read the documentation and familiarise yourself with operators and expressions: Documentation on MQL5: Language Basics / Operations and Expressions

Bitwise Operations

Left Shift (<<)

The binary representation of x is shifted to the left by y digits, the freed right-side digits are filled with zeros.

Bitwise AND Operation (&)

The bitwise AND operation of binary-coded x and y representations. The value of the expression contains a 1 (TRUE) in all digits where both x and y contain non-zero, and it contains 0 (FALSE) in all other digits.

Operations of Relation

a != b; //  True if a is not equal to b                  

Boolean Operations

Logical Negation NOT (!)

Operand of the logical negation (!) must be of arithmetic type. The result is TRUE (1), if the operand value is FALSE (0); and it is equal to FALSE (0), if the operand differs from FALSE (0).

Typecasting

(int)

That was where my Problem laying! The Typecasting! Thank you very much!

Cheers, 
Zarik

[Zarik]

fxsaber #:

Checking if the p-th bit is non-zero in the binary representation of the number m_patterns_usage.

Blees You! 

Cheers,

Zarik