21 lines
1.3 KiB
Markdown
21 lines
1.3 KiB
Markdown
# The predefined Variables
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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.
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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](/en/docs/common/resetlasterror) function.
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| Variable | Value |
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| --- | --- |
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| _AppliedTo | The _AppliedTo variable allows finding out the type of data, used for indicator calculation |
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| _Digits | Number of decimal places |
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| _Point | Size of the current symbol point in the quote currency |
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| _LastError | The last error code |
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| _Period | Timeframe of the current chart |
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| _RandomSeed | Current status of the generator of pseudo-random integers |
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| _StopFlag | Program stop flag |
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| _Symbol | Symbol name of the current chart |
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| _UninitReason | Uninitialization reason code |
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| _IsX64 | The _IsX64 variable allows finding out the bit version of the terminal, in which an MQL5 application is running |
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Predefined variables cannot be defined in a library. A library uses such variables that are defined in program from which this library is called.
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