69 lines
2.5 KiB
MQL5
69 lines
2.5 KiB
MQL5
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//+------------------------------------------------------------------+
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//| ExprRelational.mq5 |
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//| Copyright 2021, MetaQuotes Ltd. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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#property copyright "Copyright 2021, MetaQuotes Ltd."
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#property link "https://www.mql5.com"
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#property version "1.00"
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#define PRT(A) Print(#A, "=", (A))
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//+------------------------------------------------------------------+
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//| Compare 2 numbers, return true on practical equality |
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//+------------------------------------------------------------------+
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bool isEqual(const double x, const double y)
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{
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const double diff = MathAbs(x - y);
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const double eps = MathMax(MathAbs(x), MathAbs(y)) * DBL_EPSILON;
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return diff < eps;
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}
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//+------------------------------------------------------------------+
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//| Compare number for 0 with default tolerance, returns true for 0 |
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//+------------------------------------------------------------------+
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bool isZero(const double x)
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{
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return MathAbs(x) < DBL_EPSILON;
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}
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//+------------------------------------------------------------------+
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//| Script program start function |
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//+------------------------------------------------------------------+
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void OnStart()
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{
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int x = 10, y = 5, z = 2;
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// warnings: unsafe use of type 'bool' in operation
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bool range1 = x < y < z; // true (!)
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bool range2 = x < y && y < z; // false
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PRT(x < y < z);
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PRT(x < y && y < z);
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double p = 0.3, q = 0.6;
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bool eq = p + q == 0.9; // false
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double diff = p + q - 0.9; // -0.000000000000000111
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PRT(0.3 + 0.6 == 0.9);
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PRT(p + q - 0.9);
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PRT(isEqual(0.3 + 0.6, 0.9)); // true
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bool zero = 0.1 + 0.2 - 0.3 == 0; // false
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PRT(isEqual(0.1 + 0.2 - 0.3, 0)); // false
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PRT(0.1 + 0.2 - 0.3 == 0); // false
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PRT(isZero(0.1 + 0.2 - 0.3)); // true
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bool cmp1 = "abcdef" > "abs"; // false, [2]: 's' > 'c'
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bool cmp2 = "abcdef" > "abc"; // true, by length
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bool cmp3 = "ABCdef" > "abcdef"; // false, by caps
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bool cmp4 = "" == NULL; // false
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PRT("abcdef" > "abs");
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PRT("abcdef" > "abc");
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PRT("ABCdef" > "abcdef");
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PRT("" == NULL);
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}
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//+------------------------------------------------------------------+
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