Operators

X = 2 + 3 * 4; 
X = (2 + 3) * 4;

Controls the order of execution. In the first example, X will be 14. In the second, X is assigned 20.

X = .A;

A may be a variable or module. If found in the local scope, it will be assigned to X, otherwise Invalid will be returned. Note that the dot operator will not work in applications created before version 11.2 unless the application property LocalScopeSyntax is set to 1.

X = \A;

A may be a variable or module. VTScada will search through the scope tree starting with the local scope to find the closest variable or module with a matching name.

X = A[2];

Follows the name of an array or dictionary variable, and specifies which element of the array or dictionary is to be used.

This returns a number which is the real mode address with the segment before the @ and the offset after the @. This value can be used in functions such as MemIn and MemOut.

A = *X;

The example shows the opposite of the example for the Address operation.

X = &A;

Returns a pointer to the operand. A pointer is the memory address where the operand's value is stored.
To retrieve the value from the memory address stored in X you must dereference the pointer.

X = !A;

The operand should be a Boolean TRUE or FALSE (1 OR 0). Returns 0 for a logical TRUE operand and 1 for a logical FALSE operand.

A = 3;
						X = ++A;

Requires a single numeric operand. The value of the operand will be increased by one before it is used in the expression. If A initially had a value of 3 in the example given, then it would increase to 4 and that number would be assigned to X.

A = 3;
						X = A++;

Requires a single numeric operand. The value of the operand will be increased by one after it is used in the expression. If A initially had a value of 3 in the example given, then 3 would be assigned to X, following which A would increase to 4.

A = 3;
X = --A;

Requires a single numeric operand. The value of the operand will be decreased by one before it is used in the expression. If A initially had a value of 3 in the example given, then it would decrease to 2 and that number would be assigned to X.

A = 3;
X = A--;

Requires a single numeric operand. The value of the operand will be decreased by one after it is used in the expression. If A initially had a value of 3 in the example given, then 3 would be assigned to X, following which A would decrease to 2.

X = -A;

Requires a single numeric operand. Returns the negative of the value to the right without changing that value.

X = A / B;

Requires two numeric operands. Returns the result of the first divided by the second.

X = A % B;

Requires two numeric operands. Returns the remainder, being the amount left over after the maximum number of times that B can be wholly divided into A. For example, 8.5 % 3 returns 2.5
9 % 3 returns 0.

X = A * B;

Requires two numeric operands. Returns the result of the first multiplied by the second.

X = A - B;

Returns the numeric result of subtracting B from A.
Operands must be numeric.

X = A + B;

Returns the sum of two numeric operands.
Or, concatenates two strings.

It is risky to use + for concatenation. If one operand can be interpreted as a number, it will not be cast to a string and the operation will fail. Use the Concat function instead.

A = 4;
X = <<A;

Shift bits to the left. In binary, 4 is stored as 00000100. In this example, X will be assigned 00001000, or 8.

A = 4;
X = >>A;

Shift bits to the right. In binary, 4 is stored as 00000100. In this example, X will be assigned 00000010, or 2.

X = A > B;

This operator returns TRUE (1) if the first argument is strictly greater than the second, otherwise it returns false (0).
If one argument is text and the other numeric, VTScada will attempt to cast to matching types.
If both arguments are text values, the operator returns true if a letter-by-letter comparison of the ASCII codes in the first argument is greater than the second. Thus "B" is greater than "A", but not greater than "a".

X = A >= B;

The same as Greater Than, but will also return TRUE (1) if the two operands are equivalent. Does not do a test for strict equivalency. Text comparisons are case-sensitive.

X = A < B;

This operator returns TRUE (1) if the first argument is strictly less than the second, otherwise it returns false (0).
If one argument is text and the other numeric, VTScada will attempt to cast to matching types.
If both arguments are text values, the operator returns true if a letter-by-letter comparison of the ASCII codes in the first argument is lower than the second. Thus "a" is less than "b", but not less than "B".

X = A <= B;

The same as Less Than, but will also return TRUE (1) if the two operands are equivalent. Does not do a test for strict equivalency. Text comparisons are case-sensitive.

X = A == B;

Returns TRUE (1) if the two operands are equivalent.
Does not do a test for strict equivalency. VTScada will attempt to cast mismatched types to match.
Text comparisons are case sensitive. Use StrICmp for text comparisons that are not case sensitive.

X = A != B;

Returns TRUE (1) if the two operands are not equivalent.
Does not do a test for strict equivalency. VTScada will attempt to cast mismatched types to match. Text comparisons are case sensitive.

X = 0 ^ 0; { returns 0 }
X = 1 ^ 0; { returns 1 }
X = 0 ^ 1; { returns 1 }
X = 1 ^ 1; { returns 0 }

This returns the 32-bit, bitwise exclusive OR of the two operands. If either operand (but not both) is TRUE (non-0), the result is TRUE (1). If both are TRUE or both FALSE (0), the result is FALSE.

X = A && B;

Both the & and the && operators(*see note 1) take two arguments and perform the logical AND function upon them. If both arguments are true (non-0), the operator returns a true value; otherwise, a false value (0) is returned. If either argument is a valid false, the function returns false regardless of whether the other argument is valid.

The AND operator performs a bitwise comparison (32-bit).

VTScada does not use short-circuit evaluation. Both parts of the condition will always be checked (and evaluated if required).

Note 1: VTScada supports a logical "&" operator but in practice it is not used, in order to avoid confusion with the C/C++ bitwise comparison operator.

Note 2: To perform bitwise comparisons, use the AND function.

X = A || B;

The | and || operators(*see note 1) take two arguments and perform the logical OR function upon them. If either argument is true (non-0), the operator returns a true (1) value. If both arguments are false(0), the operator returns a false value(0).

If either argument is a valid true, the function returns true regardless of whether the other argument is valid. If one argument is false and the other invalid, the operator returns invalid.

The || operator performs a 32-bit, bitwise comparison.

VTScada does not use short-circuit evaluation. Both parts of the condition will always be checked (and evaluated if required).

Note 1: VTScada supports a logical "|" operator but in practice it is not used, in order to avoid confusion with the C/C++ bitwise comparison operator.

Note 2: To perform bitwise comparisons, use the OR function.

X = C ? A : B;

Equivalent to the IfElse function. Operands may be variables or expressions.

If the conditional, C, evaluates to TRUE, then expression A will be evaluated and returned. Otherwise expression B will be evaluated and returned. Note that the ? operator has a lower precedence than most other operators. You are advised to use parenthesis to control the order of evaluation if using If Else in a multi-part comparison. For example,

 A < B || C ? D : E

would be evaluated as

 ((A < B) || C) ? D : E

rather than

 (A < B) || (C ? D : E)

which is more likely what was intended.

Note that a deeply-nested set of IfElse operations can usually be replaced by simpler programming technique. Refer to the comment section in the function,IfElse

X += A;

X and A must be numeric. Adds the value of A to the value of X.

X = A;

Assigns the value of the expression on the right side of the operator to the variable on the left.

X /= A;

Requires two numeric operands. X is given the value of X / A.

X %= A;

Requires two numeric operands. X is given the remainder of X % A.

X *= A;

Requires two numeric operands. X is given the value of X * A.

X -= A;

X and A must be numeric. X is given the value X - A.