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MQL5 ReferencePredefined Variables 

The predefined Variables

For each executable mql5-program a set of predefined variables is supported, which reflect the state of the current price chart by the moment a mql5-program (Expert Advisor, script or custom indicator) is started.

Values of predefined variables are set by the client terminal before a mql5-program is started. Predefined variables are constant and cannot be changed from a mql5-program. As exception, there is a special variable _LastError, which can be reset to 0 by the ResetLastError function.

Variable

Value

_Digits

Number of decimal places

_Point

Size of the current symbol point in the quote currency

_LastError

The last error code

_Period

Timeframe of the current chart

_RandomSeed

Current status of the generator of pseudo-random integers

_StopFlag

Program stop flag

_Symbol

Symbol name of the current chart

_UninitReason

Uninitialization reason code

Predefined variables cannot be defined in a library. A library uses such variables that are defined in program from which this library is called.


Updated: 2015.12.03