Experts: A Code block to detect A "New Candle/Bar" using bars history (very effective way)

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A Code block to detect A "New Candle/Bar" using bars history (very effective way):

If you only want to execute your code blocks "only once per bar" it's important to check if there is new bar arrived or not.

A Code block to detect A "New Candle/Bar" using bars history (very effective way)

Author: Hapu Arachchilage Tharindu Lakmal

 
Assign the bars count for the "BarsTotal_OnInt" at the initialization.
Use iBars(); function to assign the bars count for the "BarsTotal_OnTick" variable at live chart. This variable is updated on every tick.
    1. Don't try to use any price (or indicator) or server related functions in OnInit (or on load or in OnTimer before you've received a tick), as there may be no connection/chart yet:
      1. Terminal starts.
      2. Indicators/EAs are loaded. Static and globally declared variables are initialized. (Do not depend on a specific order.)
      3. OnInit is called.
      4. For indicators OnCalculate is called with any existing history.
      5. Human may have to enter password, connection to server begins.
      6. New history is received, OnCalculate called again.
      7. A new tick is received, OnCalculate/OnTick is called. Now TickValue, TimeCurrent, account information and prices are valid.

    2. Unlike indicators, EAs are not reloaded on chart change, so you must reinitialize them, if necessary.
                external static variable - MQL4 programming forum #2 (2013)

  2. You can't know when a candle closes. Only when a new tick arrives that starts a new bar is the old bar closed, and that tick could arrive almost at the end of a bar's duration.

    For a new bar test, Bars is unreliable (a refresh/reconnect can change number of bars on chart), volume is unreliable (miss ticks), Price is unreliable (duplicate prices and The == operand. - MQL4 programming forum.) Always use time.
              MT4: New candle - MQL4 programming forum #3 (2014)
              MT5: Accessing variables - MQL4 programming forum #3 (2022)

    I disagree with making a new bar function, because it can only be called once per tick (second call returns false). A variable can be tested multiple times.
              Running EA once at the start of each bar - MQL4 programming forum (2011)

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