MQL4 Errors for OnCalculate

I am hoping you can help fix my code. I am trying to code a MT4 indicator to indicate a powerful downward bar.

No matter what I do, I still get :1 errors, 1 warnings

OnCalculate function declared with wrong type or/and parameters PowerfulRedBar.mq4 line 20 column6

OnCalculate function not found in custom indicator line 1 column 1

Any suggestions?

Thanks!!!

Here is what I have:

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_color1 Red
#property indicator_width1 2
extern int minBarsLeft = 5; // Number of bars to the left for comparison
extern int minRangeMultiplier = 2; // Minimum range multiplier for a powerful bar
double buffer[];
void OnInit()
{
IndicatorBuffers(1);
SetIndexBuffer(0, buffer);
SetIndexStyle(0, DRAW_ARROW);
SetIndexArrow(0, 233);
SetIndexLabel(0, "Powerful Red Bar");
}
void OnCalculate(const int rates_total,
const int prev_calculated,
const int begin,
const double& open[],
const double& high[],
const double& low[],
const double& close[],
const long& tick_volume[],
const long& volume[],
const int& spread[])
{
int startBar = MathMax(prev_calculated - minBarsLeft, 0);
for (int i = startBar; i < rates_total; i++)
{
bool isPowerfulRedBar = IsPowerfulRedBar(i, minBarsLeft, minRangeMultiplier, high, low, close, open);
buffer[i] = isPowerfulRedBar ? low[i] - (0.5 * Point) : EMPTY_VALUE;
}
}

bool IsPowerfulRedBar(const int barIndex,
const int numBarsLeft,
const int rangeMultiplier,
const double &high[],
const double &low[],
const double &close[],
const double &open[])
{
double currentRange = high[barIndex] - low[barIndex];
// Check if the bar is red
if (close[barIndex] >= open[barIndex])
return false;
// Check if the bar has the minimum range
if (currentRange < rangeMultiplier * AverageRange(barIndex, numBarsLeft, high, low))
return false;
// Check if the bar has a greater range than the bars to the left
for (int i = 1; i <= numBarsLeft; i++)
{
if ((high[barIndex - i] - low[barIndex - i]) >= currentRange)
return false;
}
return true;
}
double AverageRange(const int startIndex,
const int numBars,
const double &high[],
const double &low[])
{
double sum = 0;
for (int i = startIndex - numBars; i < startIndex; i++)
{
sum += high[i] - low[i];
}
return sum / numBars;
}

According to mql4 doc:
https://docs.mql4.com/basis/function/events
So you just need change
void OnCalculate
to
int OnCalculate

const double& spread[] gave this error in my code

const int& spread[] fix this error

any help would be nice, i am also having an on calculate error

//+------------------------------------------------------------------+
//| 1-Minute Scalping Indicator |
//| Displays buy/sell signals based on EMA, ADX, and ATR |
//+------------------------------------------------------------------+
#property strict
#property indicator_chart_window
// --- Input Parameters ---
input int FastEMA_Period = 10; // Short-term EMA for entry
input int SlowEMA_Period = 50; // Long-term EMA for trend direction
input int ADX_Period = 14; // ADX Period
input double ADX_Threshold = 20; // Minimum ADX value for trend confirmation
input double ATR_Multiplier = 1.5; // ATR Multiplier for visualization
input int Arrow_Size = 2; // Size of arrows
// --- Indicator Buffers ---
double BuySignal[], SellSignal[];
//+------------------------------------------------------------------+
//| Indicator Initialization |
//+------------------------------------------------------------------+
int OnInit()
{
IndicatorBuffers(2);
SetIndexBuffer(0, BuySignal);
SetIndexBuffer(1, SellSignal);

SetIndexStyle(0, DRAW_ARROW);
SetIndexArrow(0, 233); // Up Arrow
SetIndexStyle(1, DRAW_ARROW);
SetIndexArrow(1, 234); // Down Arrow

return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Main Calculation Function |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
const int prev_calculated,
const double &time[],
const double &open[],
const double &high[],
const double &low[],
const double &close[],
const long &volume[],
const bool &spread[])
{
if (rates_total < SlowEMA_Period) return 0;

for (int i = prev_calculated; i < rates_total; i++)
{
double FastEMA = iMA(NULL, PERIOD_M1, FastEMA_Period, 0, MODE_EMA, PRICE_CLOSE, i);
double SlowEMA = iMA(NULL, PERIOD_M1, SlowEMA_Period, 0, MODE_EMA, PRICE_CLOSE, i);
double ADX_Value = iADX(NULL, PERIOD_M1, ADX_Period, PRICE_CLOSE, MODE_MAIN, i);
double ATR_Value = iATR(NULL, PERIOD_M1, 14, i);

BuySignal[i] = 0;
SellSignal[i] = 0;

// --- Buy Signal ---
if (close[i - 1] > SlowEMA && close[i] > FastEMA && ADX_Value > ADX_Threshold)
{
BuySignal[i] = low[i] - ATR_Value * ATR_Multiplier;
}

// --- Sell Signal ---
if (close[i - 1] < SlowEMA && close[i] < FastEMA && ADX_Value > ADX_Threshold)
{
SellSignal[i] = high[i] + ATR_Value * ATR_Multiplier;
}
}

return(rates_total);
}

OnCalculate function declared with wrong type or/and parameters scalp2.mq4 39 5
OnCalculate function not found in custom indicator 1 1
1 errors, 1 warnings 2 2