Difference between revisions of "Lianja Operators"
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Revision as of 01:44, 9 December 2012
Contents
Lianja Operators
Assignment Operators
Values are assigned to memory variables using the the equals = operator.
cVar1 = 'newer value'
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:
Operator | Operation | Precedence |
---|---|---|
() | Parentheses | 1 |
** ^ | Exponentiation | 2 |
* | Multiplication | 3 |
/ | Division | 3 |
% | Modulus/Remainder | 3 |
+ | Addition | 4 |
- | Subtraction | 4 |
When dealing with Date data types, the operators work as follows:
Operator | Operation |
---|---|
+ | <expD> + <expN> returns a date plus the number of days specified in <expN>. |
- | Returns the interval between the two dates as a number of days. |
Example
? 2*3^2 18 ? 2*25%7 1.00 ? date() + 30 - date() 30
Comparison Operators
The following comparison operators are supported in Lianja:
Operator | Operation |
---|---|
= | Equal To |
== | Exactly Equal To / Matches Pattern |
<> | Not Equal To |
!= | Not Equal To |
# | Not Equal To |
> | Greater Than |
>= | Greater Than or Equal To |
< | Less Than |
<= | Less Than or Equal To |
The comparison operators are always evaluated from left to right.
The following ’wildcard’ characters can be used for == pattern matching:
Character | Action |
---|---|
? | Matches any one character |
% | Matches any one character |
* | Matches zero or more characters |
In SQL statements, the following wildcard characters are available:
Characters | Description |
---|---|
_ | Matches any one character |
% | Matches zero or more characters |
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:
Operator | Operation |
---|---|
.AND. / AND | Logical AND |
.OR. / OR | Logical OR |
.NOT./ NOT | Logical NOT |
! | Logical NOT |
.XOR. / XOR | Logical Exclusive OR |
The logical operators are evaluated from left to right in the following order:
- Statements enclosed in parentheses
- NOT,!
- AND
- 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:
Operator | Operation |
---|---|
+ | Concatenate the right hand string to the end of the left hand string. |
- | Concatenate the right hand string to the end of the left hand string after trimming the left hand string of trailing spaces. |
Example
? [Hello] + [ ] + [ World] Hello World ? [Hello ] - [ World] Hello World
String Search Operators
The following string search operators are supported in Lianja:
Operator | Operation |
---|---|
$ | Substring is Contained In |
| | Contains Substring |
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
Concatenation of Strings and Other Data Types
If set strict is off, non-string expressions are automatically converted as they are added to a string. If set strict is on, expressions must be converted manually using the etos() or other data conversion functions. By default, set strict is on.
Example
set strict off echo "This string can add numerics and dates etc. " + 100.89 + " " + date() set strict on echo "This string can add numerics and dates etc. " + str(100.89,6,2) + " " + etos(date())