eva/3 Application Builder • Developing eva/3 Applications • Working with expressions

Operators

Expressions allow the calculation of values under comprehension of values from form- or report components.

Ranking of the operators

If more than one operator is combined in a expression, then the operators are run from left to right in their ranking. Affection of the rank can happen by brackets.

Possible operators

An Expression can be made up from one or more of the following operators:

Arithmetic operators		Ranking
+	The add operator allows the addition of numeric values. If one of the operands is a string, then the concatination function will be compute on the add operator , that means both operands will be added. This operator can be used as sign for numeric operands. Numeric values, strings or functions and objects returning numeric values can be used as legal operands. All legal operands can be mixed. The returned value of the operation is always a number, if both operands contain numeric values. If a string builded by the add operator generates a date, a constant or a number, then the adapted data type is returned. Example: =5+5 with the result 10 =5+"5" with the result 55 =5+-5 with the result 0 =5+"5"+5 with the result 60	3
-	The subtraction operators allows the subtraction of numeric values. This operator can be used as sign for numeric operands. Numeric values, or functions and objects returning numeric values can be used as legal operands. The returned value of the operation is always a number. Example: =5-5 with the result 0	3
*	The multiplication operator allows the multiplication of numeric values. Multiplication- and division operators are computed at first. As legal operands can be used numeric values, or functions and objects returning numeric values. The returned value of the operation is always a number. Example: =55* with the result 25	2
/	The division operator allows the division of numeric values. Division- and multiplication operators will be computed at first. As legal operands can be used nummeric values, or functions und objects returning numeric values. The returned value of the operation is always a number. Example: =5/2 with the result 2.5	2
%	Modulo operators allows the determination of the modulo value (salvage value) of numeric values. As legal operands can be used nummeric values, or functions and objects returning numeric values. The returning value of the operation is always a number. Example: =8/2 with the result 0	2
^	The potentiation operator (caret-character) allowst the determination of the power of a numeric value. As legal operands can be used numeric values, or funktions and objects returning numeric value. The returning value of the operation is always a number. Example: =3^3 with the result 27	1
&	Concatenation operator allows the concatenation of two values. The concatenation operator will be computed at last. The concatenation operator connects the results former operations. Legal operands can be used as numeric values, date values, strings or constants . The returned value of the operation is always a string. Example: ="Wert: "&5 with the result Wert: 5 =5+5&5+5 with the result 1010	5

Logical operators connect boolean values which also can be generated from a former or suceeding operaton or function . Logical operators also can deal with combinations where the first operand of a operation alludes to the first operand of a previous function.

Beispiel: =#1.1.2005# > #1.1.2004# and > #1.1.2003#

Logical operators		Rangfolge
AND - &&	The and-operator combines two boolean constants. Both boolean constants have to contain the value true to get the returned value true after the operation. Every other combination results in the return value false. Legal operands can only be boolean values. The returned value is always a boolean value. Example: =true and true with the result true =true and false with the result false =false and false with the result false	7
NAND - &&	The and-operator combines two boolean constants in a NOT AND assignment. Legal operands can only be boolean values. The returned value is always a boolean value. Example: false NAND false = true false NAND true = true true NAND false = true true NAND true = false	7
OR - \|\|	The or-operator combines two boolean constants. If one of the boolean constants owns the value true then the returned value also is true. Legal operands can only be boolean values. The returned value is always a boolean value. Example: =true or true with the result true =true or false with the result true =false and false with the result false	7
NOR	The or-operator combines two boolean constants in a NOT OR assignment. Legal operands can only be boolean values. The returned value is always a boolean value. Example: false NOR false = true false NOR true = false true NOR false = false true NOR true = false	7
XOR	The xor-operator combines two boolean constants in an exclusive OR assignment. Legal operands can only be boolean values. The returned value is always a boolean value. Example: false XOR false = false false XOR true = true true XOR false = true true XOR true = false	7
XNOR	The xnor-operator combines two boolean constants in an exclusive NOT OR assignment. Legal operands can only be boolean values. The returned value is always a boolean value. Example: false XNOR false = true false XNOR true = false true XNOR false = false true XNOR true = true	7
NOT - NICHT	The not-operator inverts the following boolean value. Legal operands can only be boolean values . The Returned value is always a boolean value. Example: =not true with the result false =not false with the result true	7

The comparison operator serves as differentiation of size or rather valence of a numeric or rather alpha numeric value or a string. The result of a comparison operator is always a boolean value.

Comparison operators

Ranking

The bigger than operator compares for the bigger of two operands. Are both operands numeric values, than the higher applies as the bigger ones. Are both operands data values, than the date with the later moment is the bigger one. The result is true if the left operand is bigger than the right operand.

Legal operands are numeric values and date values. Just as well returned values can be used by functions or objects which accord to the foresaid operand types.

Example: =5>6 with the value false
=1.1.2005>30.12.2004 with the value true

The smaller than operator compares for the smaller of two operands. Are both operands numeric values, than the lower applies as the smaller ones. Are both operands data values, than the date with the former moment is the smaller one. The result is true if the left operand is smaller than the right operand.

Legal operands are numeric values and date values. Just as well returned values can be used by functions or objects which accord to the foresaid operand types.

Example: =5<6 with the result true
=1.1.2005<30.12.2004 with the result false

The bigger equal operator owns the same properties like the > bigger than operator, but also asseses two operands as true, if both operands have the same size.

Legal operands are numeric values and date values. Just as well returned values can be used by functions or objects which accord to the foresaid operand types.

Example: =5<=5 with the result true

The smaller equals oerator owns the same properties like the < smaller than operator, but also asseses two operands as true, if both operands have the same size.

Legal operanden are numeric values and date value. Just as well returned values can be used by functions or objects which accord to the foresaid operand types.

Example: =5>=5 with the result true

==
-
=

The equals operator owns the returned value true if both values have the same values.

Legal operands are numeric values, constants, strings and date values. Just as welll returned values of objects or functions can be used. The operand types can´t be mixed. With the exception of the constant null, which can be compared with all types.

Example: =5==5 with the result true
=true==false with the result false

!=
-
<>

The not equal operator owns the returned value true if both values have a different value.

Legal operands are numeric values, constants, strings and date values. Just as welll returned values of objects or functions can be used. The operand types can´t be mixed. With the exception of the constant null, which can be compared with all types.

Example: =5!=5 with the result false
=true!=false with the result true

Is used for comparing of a string with a search pattern.

Patterns can contain the complete value (for example Like "Meier") or replacement character, to find an area of values (for example Like "Mei*"). Upper- and lowercase is ignored. Possible replacement characters are:

type	model	adapted	not adapted
many characters	a*a	aa, aBa, aBBBa	aBC
special characters	a[*]a	a*a	aaa
single characters	a?a	aaa, a3a, aBa	aBBBa
single numerals	a#a	a0a, a1a, a2a	aaa, a10a
character area	[a-z]	f, p, j	2, &
out of the character area	[!a-z]	9, &, %	b, a
no numeral Ziffer	[!0-9]	A, a, &, ~	0, 1, 9
combination	a[!b-m]#	An9, az0, a99	abc, aj0

Example: ="aaab" like "a*b" with the result true

BETWEEN

Determines, if the value of a expression is located in a specified area of values. Allowed values are numbers and date values.

Example: =5000 between 4000 and 6000 with the result true
=#1.1.2005# between #1.1.2006# and #1.1.2004# with the result true
=#1.1.2005# not between #1.1.2006# and #1.1.2004# with the result false

Assignment opperators can be used to assign values to a variable.

Assignment operators		Ranking
<-	Assigns the value at the right to the variable at the left of the assignment operator. If the value to be assigned should be calculated first, it should be set into braces. Example: =$i<-5 with the value 5	0
->	Assigns the value at the left to the variable at the right of the assignment operator. If the value to be assigned should be calculated first, it should be set into braces. Beispiel: =$i->5 mit dem Ergebnis 5	0

Increment and decrement operators allows to higher or lower a numeric value by one. This takes also an effekt to variables containing a numeric value.

Increment and decrement		Rangfolge
++	Enlarges a numeric value by one. Example: =4++ with the result 5	-1
--	Decrease a numeric value by one. Example: =4- - with the result 3	-1

Working with expressions