Arithmetic, Logical and Comparison Operators

Here is a list of the available operators in a SIL™ program and detailed usage information.

Arithmetic operators

In version 2.5 (and 3.0 yet again) we have reworked the way operators handle different types and conversions by putting an emphasis on the left-hand side (LHS) value of the operation. Consequently, only the right-hand side (RHS) operand will be converted (if necessary) to a type that is valid for the current operation with the LHS type.

For each operator and LHS type, we define two lists: valid types and convertible types. The list of convertible types is based on Type Conversion. This creates three cases:

If the RHS type is one of the valid types, then the operation will proceed as it is and the result calculated according to the table below.
If the RHS type is one of the convertible types, then it will attempt to convert it to one of the valid types (in the order the valid types are presented in the table below) until the conversion succeeds and then proceeds according to case 1.
If the RHS type is neither valid nor convertible, the program will end in error.

Operator	LHS type	RHS types	Result	Explanations and Usage
+	number	number	number	standard addition of numbers
	number	integer	number	standard addition of numbers
	integer	integer	integer	standard addition of integers
	integer	number	integer	standard addition of integers
	string	string	string	adds the string representation of the RHS operand at the end of the LHS string
	boolean	Unsupported
	date	interval	date	adds the interval to the date and returns the result
	interval	interval	interval	adds the two intervals and returns the result
	interval	date	date	adds the interval to the date and returns the result
	<type> []	<type>	<type> []	adds the RHS value to the LHS array, where <type> can be any type.
-	number	number	number	standard subtraction of numbers
	number	integer	number	standard subtraction of numbers
	integer	integer	integer	standard subtraction of integers
	integer	number	integer	standard subtraction of integers
	string	string	string	removes all occurrences of the RHS string in the LHS value
	boolean	Unsupported
	date	date	interval	returns the interval difference between the two dates
	date	interval	date	subtracts the RHS interval from the date and returns the value
	interval	interval	interval	standard interval subtraction
	<type>[]	<type>	<type>[]	removes the first occurrence of the RHS value from the array; <type> can be any type.
*	number	number	number	standard multiplication of numbers
		integer	number	standard multiplication of numbers
		interval	interval	multiplies the interval by the number of times specified by the LHS operand and returns the result
	number []	number	number []	multiplies each value in the LHS array with the number in the RHS operand and returns the result
	number []	integer	number []	multiplies each value in the LHS array with the integer in the RHS operand and returns the result
	integer	integer	integer	standard multiplication of integers
		number	integer	standard multiplication of integers
		interval	interval	multiplies the interval by the integer of times specified by the LHS operand and returns the result
	integer []	integer	integer []	multiplies each value in the LHS array with the integer in the RHS operand and returns the result
	integer []	number	integer []	multiplies each value in the LHS array with the number in the RHS operand and returns the result
	string	Unsupported
	boolean	Unsupported
	date	Unsupported
	interval	number	interval	multiplies the interval by the number of times specified by the RHS operand and returns the result
	<type>[] (except number)	Unsupported
/	number	number	number	standard division of numbers
	number	integer	number	standard division of numbers
	number []	number	number []	divides each value in the LHS array by the number in the RHS operand and returns the result
	number []	integer	number []	divides each value in the LHS array by the integer in the RHS operand and returns the result
	integer	integer	integer	standard division of integers
	integer	number	integer	standard division of integers
	integer []	integer	integer []	divides each value in the LHS array by the integer in the RHS operand and returns the result
	integer []	number	integer []	divides each value in the LHS array by the number in the RHS operand and returns the result
	string	Unsupported
	boolean	Unsupported
	date	Unsupported
	interval	number	interval	divides the interval by the number specified in the RHS operand
	<type>[] (except number)	Unsupported
%	number	number	number	standard modulo division of numbers
	number	integer	number	standard modulo division of numbers
	number []	number	number []	applies the modulo operator on each number in the LHS array with the number in the RHS operand and returns the results
	number []	integer	number []	applies the modulo operator on each number in the LHS array with the integer in the RHS operand and returns the results
	integer	integer	integer	standard modulo division of integers
	integer	number	integer	standard modulo division of integers
	integer []	integer	integer []	applies the modulo operator on each number in the LHS array with the integer in the RHS operand and returns the results
	integer []	number	integer []	applies the modulo operator on each number in the LHS array with the number in the RHS operand and returns the results
	string	Unsupported
	boolean	Unsupported
	date	Unsupported
	interval	Unsupported
	<type>[] (except number)	Unsupported

You can also use the combined forms of the arithmetic operators with the attrib operator: +=, -=, *= and /=.

string s = "a";
s = s + "b";
// is equivalent with
s += "b";

Numbers also support the pre/post increment/decrement operators.

--i; 
i--;
++i;
i++;

Comparison operators

Operator	Operands	Return	Explanations and Usage
== (alias 'eq')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns true if the values are equal and false otherwise.
!= (alias 'neq')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns false if the values are equal and true otherwise.
< (alias 'lt')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns true if the first value is lower than the second one and false otherwise.
> (alias 'gt')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns true if the first value is greater than the second one and false otherwise.
<= (alias 'le')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns true if the first value is lower then or equal to the second one and false otherwise.
>= (alias 'gt')	Right operand will be casted to the left operand's type if their types are different	true/false	Returns true if the first value is greater than or equal to the second one and false otherwise.

Logical operators

Operator	Operands	Return	Explanations and Usage
&& (alias 'and')	boolean && boolean	true/false	Logical "and"
\|\| (alias 'or')	boolean \|\| boolean	true/false	Logical "or"
! (alias 'not')	boolean	true/false	Logically complements of the specified boolean.
! (alias 'not')	number	number	Complements the number in relation to 0. (returns number * -1)

Ternary operators

Operator

Operands

Return

Explanations and Usage

?:

boolean, <type>, <type>

<type>

<condition> ? <ifTrueValue> : <ifFalseValue>

If <condition> is true, returns <ifTrueValue>, otherwise returns <ifFalseValue>.

Note that <ifTrueValue> and <ifFalseValue> must have same type.

The Indexing Operator

The basic use of the indexing operator (introduced in version 2.5) is to allow you to easily access the contents of a list.

General syntax

string [] arr = {"a", "b", "c"};
string contents = arr[0] + arr[1] + arr[2] + arr[3]; // as user friendly as arrayGetElement, if index is out of bounds, will return an empty value.
arr[3] = "d";

Moreover, it allows you to create key-value lists (maps) and retrieve values from them by using a string inside the operator (instead of a number).

number [] map;
map["one"] = 1;
map["two"] = 2;
print(map["one"]);
// note that when used in a for-loop, map only has 2 elements: 1 and 2. The keys will be hidden.
print(map); // will print 1|2

When accessing a map as a list, the contents are retrieved in the order they were added. You can still use the operator with an integer value even on maps.

date [] days;
days["yesterday"] = currentDate() - "1d";  // added as first element
days["today"] = currentDate();		   // added as second element
days["tomorrow"] = currentDate() + "1d";   // added as third element
if(days["today"] == days[1]){
	print("Today is the second element in the array"); // yes, this will be printed
}

The indexing operator can also be used with certain simple types (not arrays) and a specific value to provide additional functionality.

SIL™ type	Index Value	Get	Get Return Type	Set
string	a number	Gets the character at the specified index in the string	string	Inserts a character at the specified index. If given a longer string, it will insert the first character of the string.
date	"DAY"	Gets the day of month from the date	integer	Unsupported
	"MONTH"	Gets the month from the date	integer	Unsupported
	"YEAR"	Gets the year from the date	integer	Unsupported
	"HOUR"	Gets the hour (0-23) from the date	integer	Unsupported
	"MINUTE"	Gets the minute (0-59) from the date	integer	Unsupported
	"SECOND"	Gets the seconds (0-59) from the date	integer	Unsupported
	"MILLISECOND"	Gets the milliseconds (0-999) from the date	integer	Unsupported
	"WEEK"	Gets the week number within the current year	integer	Unsupported
	"WEEKINMONTH"	Gets the week number within the current month	integer	Unsupported
	"TOMILLIS"	Gets the current time as UTC milliseconds from the epoch.	integer	Unsupported
	"DAYOFWEEK"	Gets the three letter format for the day of the week (e.g. "Mon", "Tue", "Wed" etc)	string	Unsupported
	"MONTHNAME"	Gets the three letter format for the name of the month (e.g. "Jan", "Feb", "Mar", etc.)	string	Unsupported
interval	"WEEK"	Gets the number of whole weeks inside the interval (e.g. interval i = "1w 14d"; i["WEEK"] will return 3)	integer	Unsupported
	"DAY"	Gets the number of whole days inside the interval (e.g. interval i = "1d 48h"; i["DAY"] will return 3)	integer	Unsupported
	"HOUR"	Gets the number of whole hours inside the interval (e.g. interval i = "1h 120m"; i["HOUR"] will return 3)	integer	Unsupported
	"MINUTE"	Gets the number of whole miuntes inside the interval (e.g. interval i = "1m 120s"; i["MINUTE"] will return 3)	integer	Unsupported
	"SECOND"	Gets the number of seconds inside the interval (e.g. interval i = "1h 1m 3s"; i["SECOND"] will return 3)	integer	Unsupported
	"TOMILLIS"	Gets the number of milliseconds inside the interval	integer	Unsupported

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