bool SymbolInfoDouble	(	string	name,
		int	prop_id,
		out double	double_var
	)

Returns the corresponding property of a specified symbol

Parameters

name	Symbol name
prop_id	Identifier of a symbol property. The value can be one of the following values: SYMBOL_BID Bid - best sell offer SYMBOL_ASK Ask - best buy offer SYMBOL_POINT Symbol point value SYMBOL_TRADE_TICK_VALUE Value of SYMBOL_TRADE_TICK_VALUE_PROFIT SYMBOL_TRADE_TICK_SIZE Minimal price change SYMBOL_TRADE_CONTRACT_SIZE Trade contract size SYMBOL_VOLUME_MIN Minimal volume for a deal SYMBOL_VOLUME_MAX Maximal volume for a deal SYMBOL_VOLUME_STEP Minimal volume change step for deal execution SYMBOL_SWAP_LONG Buy order swap value SYMBOL_SWAP_SHORT Sell order swap value SYMBOL_MARGIN_INITIAL Initial margin means the amount in the margin currency required for opening an order with the volume of one lot. It is used for checking a client's assets when he or she enters the market. SYMBOL_MARGIN_MAINTENANCE The maintenance margin. If it is set, it sets the margin amount in the margin currency of the symbol, charged from one lot. It is used for checking a client's assets when his/her account state changes. If the maintenance margin is equal to 0, the initial margin is used.
double_var	Variable of double type receiving the value of the requested property

Returns

True if exceution is successfull, otherwise false. In case of execution failure, information about the error can be obtained using GetLastError() function:

• 5040 – invalid string parameter for specifying a symbol name,
• 4301 – unknown symbol (financial instrument),
• 4302 – symbol is not selected in "Market Watch" (not found in the list of available ones),
• 4303 – invalid identifier of a symbol property.

It is recommended to use SymbolInfoTick() if the function is used for getting information about the last tick.
It may well be that not a single quote has appeared yet since the terminal is connected to a trading account. In such a case, the requested value will be indefinite.
In most cases, it is enough to use SymbolInfoTick() function allowing a user to receive the values of Ask, Bid, Last,
Volume and the time of the last tick's arrival during a single call.