Declaring Variables with NinjaScript

Brief Introduction

We’ve put together a series of posts to help you in your journey to learn how to program from scratch, or edit existing NinjaTrader indicators and strategies. All of our posts are geared toward the non-programmer, so even though we will present a lot of information, for all of you more technical people out there, we will not go into all the technicalities of C#, NinjaTrader, or NinjaScript. It’s also important to note that even though we show you how to do something in NinjaTrader, that is by no way the only way to do it. We will present what has worked best for us and what will be most easily understood by someone learning how to program. Finally, for the more advance users, we are going to leave things out and over simplify certain parts because we are focused on learning what we need to so we can get started on our NinjaScript journey.

Variables are integral to programming indicators. Think of a variable as a name such as Period that holds a value (or something we want to keep track of and reference later), such as 8 (the value does not have to be a number). The value could also be a string such as Variable, it could contain a decimal 8.5354, it could be True, or it could even be Null (there are more options, but let’s stick with the basics). Variables help us easily reference a number, or calculation and they come in all different varieties.

Common Data Types

When we create (declare) a variable, we can declare that variable as one of many different data types. I will present a few of the most common and as we progress, I will introduce more through the use of examples (even though the following list looks intimidating, the most common Data Types we use are int, double, and string):

Table Source: https://msdn.microsoft.com/en-us/library/ms228360(v=vs.90).aspx

Short Name	.NET Class	Type	Width	Range (bits)
byte	Byte	Unsigned integer	8	0 to 255
sbyte	SByte	Signed integer	8	-128 to 127
int	Int32	Signed integer	32	-2,147,483,648 to 2,147,483,647
uint	UInt32	Unsigned integer	32	0 to 4294967295
short	Int16	Signed integer	16	-32,768 to 32,767
ushort	UInt16	Unsigned integer	16	0 to 65535
long	Int64	Signed integer	64	-9223372036854775808 to 9223372036854775807
ulong	UInt64	Unsigned integer	64	0 to 18446744073709551615
float	Single	Single-precision floating point type	32	-3.402823e38 to 3.402823e38
double	Double	Double-precision floating point type	64	-1.79769313486232e308 to 1.79769313486232e308
char	Char	A single Unicode character	16	Unicode symbols used in text
bool	Boolean	Logical Boolean type	8	True or false
object	Object	Base type of all other types
string	String	A sequence of characters
decimal	Decimal	Precise fractional or integral type that can represent decimal numbers with 29 significant digits	128	±1.0 × 10e−28 to ±7.9 × 10e28

Variable Examples

I get it, my last table didn’t make that much sense. I only included it as reference for later, but the best way to demonstrate variables is through an example, but before we do that, we need to open a NinjaScript Output window. Go to your Control Center and navigate to New -> NinjaScript Output. A new window should appear that looks like this:

When we edit the indicator from Part 1, we will Print text that will appear in the NinjaScript Output window. So, let’s look at some examples of how to declare variables:

Before you add the above to a chart and see what happens in the NinjaScript Output window, you need to save and compile (see Part 1). After your indicator compiles (sound will play and no errors appear) and you load the indicator on a chart, you should see this in your NinjaScript Output window:

It’s As Simple As That

Declaring variables is as simple as that. Now it’s time to checkout Part 3 – If Statements.