Coming from MQL4 and MQL5

A real import, the ideas side by side, and the names that translate.

This is a real run of the importer on a small MQL4 and MQL5 script. The result compiles. 11 lines were read: 6 carried over exactly, 6 were adapted and 2 came back as decisions for you.

What you paste · MQL4

#property strict
input int Fast = 20;
input int Slow = 50;
input double Lots = 0.10;
void OnTick()
{
double f = iMA(NULL, 0, Fast, 0, MODE_EMA, PRICE_CLOSE, 0);
double s = iMA(NULL, 0, Slow, 0, MODE_EMA, PRICE_CLOSE, 0);
if (f > s && OrdersTotal() == 0)
OrderSend(Symbol(), OP_BUY, Lots, Ask, 3, Ask - 250 * Point, Ask + 500 * Point);
}

What you get back

1strategy "Imported expert advisor"
2market: EURUSD
3bars: 1h
4
5input Fast = 20
6input Slow = 50
7input Lots = 0.1 lots
8
9f = ema(close, Fast)
10s = ema(close, Slow)
11
12when f > s and trades.open().len == 0:
13buy size: Lots, stop: close - 250 * market.point_size, target: close + 500 * market.point_size

Line by line

Status	Your line	What happened
Exact	`input int Fast = 20 ;`	an input carried over
Exact	`input int Slow = 50 ;`	an input carried over
Exact	`input double Lots = 0.10 ;`	an input carried over
Adapted	`void OnTick ( )`	OnTick became the script body, which runs once per bar; add evaluate: tick to run on every tick
Exact	`double f = iMA ( NULL , 0 , Fast , 0 , MODE_EMA`	a variable carried over
Exact	`double s = iMA ( NULL , 0 , Slow , 0 , MODE_EMA`	a variable carried over
Adapted	`f > s && OrdersTotal ( ) == 0`	OrdersTotal() became the number of open trades
Your call	`Symbol ( )`	Symbol() has no equivalent yet
Adapted	`Ask`	Ask became the close: a backtest here has one price per bar, and live trading uses the right side of the spread
Adapted	`Ask - 250 * Point`	Ask became the close: a backtest here has one price per bar, and live trading uses the right side of the spread
Adapted	`Ask + 500 * Point`	Ask became the close: a backtest here has one price per bar, and live trading uses the right side of the spread
Exact	`OrderSend ( Symbol ( ) , OP_BUY , Lots , Ask , 3 ,`	the order carried over with its stop and target
Adapted	`if ( f > s && OrdersTotal ( ) == 0 ) OrderSend (`	a condition that places orders became a rule
Your call	`the script header`	an expert advisor runs on whatever chart it is attached to, so EURUSD on 1h was filled in: set the ones you want

How the ideas translate

In MQL4 and MQL5	In AlgoBarsX
`input int Fast = 20;`	input Fast = 20
`input double Lots = 0.10;`	input Lots = 0.1 lots
`iMA(NULL, 0, Fast, 0, MODE_EMA, PRICE_CLOSE, 0)`	ema(close, Fast)
`OrdersTotal() == 0`	trades.open().len == 0
`OrderSend(Symbol(), OP_BUY, Lots, Ask, 3, sl, tp)`	buy size: Lots, stop: …, target: …
`Point`	market.point_size
`PERIOD_H1, PERIOD_D1`	1h, 1d
`void OnTick()`	the body of the script. Add evaluate: tick to the header if it must run inside the bar.

Tip. Stops written as Ask - 250 * Point carry over literally. They read better, and survive gaps better, as distances: stop: 250 points.

Names the importer translates for you

Their name	AlgoBarsX
`mode_sma`	`sma`
`mode_ema`	`ema`
`mode_smma`	`smma`
`mode_lwma`	`wma`
`price_close`	`close`
`price_open`	`open`
`price_high`	`high`
`price_low`	`low`
`price_median`	`hl2`
`price_typical`	`hlc3`
`price_weighted`	`ohlc4`
`mathabs`	`abs`
`mathmax`	`max`
`mathmin`	`min`
`mathround`	`round`
`mathfloor`	`floor`
`mathceil`	`ceil`
`mathsqrt`	`sqrt`
`mathlog`	`log`
`mathexp`	`exp`
`mathpow`	`pow`
`mathsign`	`sign`
`_symbol`	`market.symbol`
`symbol`	`market.symbol`
`_point`	`market.point_size`
`point`	`market.point_size`
`bars`	`bar.index`
`period_m1`	`1m`
`period_m5`	`5m`
`period_m15`	`15m`
`period_m30`	`30m`
`period_h1`	`1h`
`period_h4`	`4h`
`period_d1`	`1d`
`period_w1`	`1w`
`period_mn1`	`1M`

Read every import before you run it. Compare the plain-English description with what your original did, settle each decision, and backtest before you deploy.