php-binance-api.php
public function buy(string $symbol, $quantity, $price, string $type = "LIMIT", array $flags = [])
    {
        return $this->order("BUY", $symbol, $quantity, $price, $type, $flags);
    }
public function buy(string $symbol, $quantity, $price, string $type = "LIMIT", array $flags = [])
    {
        return $this->order("BUY", $symbol, $quantity, $price, $type, $flags);
    }
public function buy ( string $ symbol , $ quantity , $ price , string $ type = "LIMIT" , array $ flags = [ ] ) { return $ this -> order ( "BUY" , $ symbol , $ quantity , $ price , $ type , $ flags ) ; }
buy attempts to create a currency order
each currency supports a number of order types, such as
-LIMIT
-MARKET
-STOP_LOSS
-STOP_LOSS_LIMIT
-TAKE_PROFIT
-TAKE_PROFIT_LIMIT
-LIMIT_MAKER

You should check the @see exchangeInfo for each currency to determine
what types of orders can be placed against specific pairs

$quantity = 1;
$price = 0.0005;
$order = $api->buy("BNBBTC", $quantity, $price);

@param $symbol string the currency symbol
@param $quantity string the quantity required
@param $price string price per unit you want to spend
@param $type string type of order
@param $flags array addtional options for order type
@return array with error message or the order details
buy attempts to create a currency order each currency supports a number of order types such as - LIMIT - MARKET - STOP_LOSS - STOP_LOSS_LIMIT - TAKE_PROFIT - TAKE_PROFIT_LIMIT - LIMIT_MAKER