Difference between revisions of "Lianja Operators"

Latest revision as of 05:55, 6 April 2018

Lianja Operators

Assignment Operators

Values are assigned to memory variables using the the equals = operator.

cVar1 = 'newer value'

The following assignment operator is also supported for Numeric and Character data types:

nVar1 = 10
nVar1 += 10  // 10 + 10 = 20
cVar1 = "Hello "
cVar1 += "World" // "Hello " + "World" = "Hello World"

The following assignment operators are also supported for Numeric data types:

nVar1 = 20
nVar1 -= 10  // 20 - 10 = 10
nVar1 *= 10  // 10 * 10 = 100
nVar1 /= 10  // 100 / 10 = 10
nVar1 %= 3   // 10 % 3 = 1

Note that the store command can also be used to assign values and can operate on more than one memory variable in a single command.

store 'new value' to cVar1, cVar2

Arithmetic Operators

Lianja supports the use of the following arithmetic operators:

When dealing with Date data types, the operators work as follows:

Example

? 2*3^2
        18
? 2*25%7
      1.00
? date() + 30 - date()
        30

Comparison Operators

The following comparison operators are supported in Lianja:

The comparison operators are always evaluated from left to right.

The following ’wildcard’ characters can be used for == pattern matching:

In SQL statements, the following wildcard characters are available:

Example

cStr1 = [Welcome to Lianja]
? "Lianja" $ cStr1
.T.
 
cStr2 = [Welcome]
// Compares to the end of cStr2
? cStr1 = cStr2
.T.
 
// Compare contents & size
? cStr1 == cStr2
.F.

Logical Operators

Lianja supports the following logical operators:

The logical operators are evaluated from left to right in the following order:

1. Statements enclosed in parentheses
2. NOT,!
3. AND
4. OR, XOR

Example

? .T. and .F. or .T.
.T.

Increment and Decrement Operators

The ++ operator is used to automatically increment a previously declared numeric memory variable by one. The ++ operator must be placed at the beginning of the command line.

Example

i=0
do while i <100
    ++ i
enddo

The -- operator is used to automatically decrement a previously declared numeric memory variable by one. The -- operator must be placed at the beginning of the command line.

Example

i=100
do while i > 0
    --i
enddo

String Concatenation Operator

When dealing with string data types, the + and - operators perform the following concatenation operations:

Example

? [Hello] + [ ] + [ World]
Hello World
? [Hello     ] - [ World]
Hello World

String Search Operators

The following string search operators are supported in Lianja:

String Substitution Operator

&<memvar> | (<exp>)

The & string substitution or 'Macro' operator substitutes the contents of the specified <memvar> or evaluated expression, (<exp>), into the command line. To use a macro in the middle of a word, it is necessary to end the variable name with a '.'. Any type of memory variable can be substituted as a macro; expressions must be enclosed in round brackets.

Example

subscript = 10
i10i = 5
? i&subscript.i
         5

& macro substitution is also supported in the Command Window, Console Workspace and Console Tab in the App Inspector from v4.1.

Concatenation of Strings and Other Data Types

If set strconvert is on, non-string expressions are automatically converted as they are added to a string. If set strconvert is off, expressions must be converted manually using the etos() or other data conversion functions. By default, set strconvert is off.

Example

set strconvert on
echo "This string can add numerics and dates etc. " + 100.89 + " " + date()
 
set strconvert off
echo "This string can add numerics and dates etc. " + str(100.89,6,2) + " " + etos(date())

NEW Operator

The NEW Operator is used to create a new object based on a class. CREATEOBJECT() and NEWOBJECT() can also be used to create objects.

Example

define class product as custom
	productname = "Lianja App Builder"
	version = "3.4"
	proc init(arg1)
		? etos(arg1)
	endproc
	proc getver
		? this.version
	endproc
enddefine
 
oProduct = new product("Hello World")
oProduct.getver()
? oProduct.productname
 
Hello World
3.4
Lianja App Builder