Overview of the Expression Engine Language

// Declaration of integer z
integer z
// Assignment statement
z=x+y

x<=y

// declarations
integer x; /*semicolon is safely ignored, and can use C-style comments*/
real y
 
// statements 
x=10 y=12.4 /* more than one statement can be on a line */

["static"]["private"|"public"]["hidden"|"visible"] type[(*size)] ["array"] identifier

"integer"|"string"|"real"|"boolean"|"date"

// a 30-character string available
// only to the code block
private string(30) name

// a 30-byte string
string(30 bytes) name
 
// a 255-character public string
string address
 
// a global real number
global real number
 
// a public date field. Use back
// quotes if symbols include spaces
date `birth date`

statement:
| "goto" label
| identifier "=" expression
| "return" expression
| "if" expression ["then"] statement ["else" statement]
| "for" identifier ["="] expression ["to"] expression ["step" expression] statement
| "begin" statement [statement...] "end"
| ["call"] function
| "while" expression statement
 
label: identifier ":"
 
expression:
described later
 
function: identifier "(" parameter [,parameter...] ")"

integer x
x=0
// label statement called start
start:
     x=x+1 
     if x < 10 goto start

integer num 
string str
date dt 
boolean b 
real r 
 
// assign 1 to num
num=1 
// assign Jan 28 '03 to the date symbol
dt=#01/28/03#
// sets boolean to true
b=true 
// also sets boolean to true
b='yes' 
// sets real to 30.12 (converting from string)
r="30.12" 
// sets string to the string representation of the date
str=dt 
// sets num to the rounded value of r
num=r

// only include rows where ID >= 200
if id < 200
     return false

string(20) person
integer x
integer y
integer age
Age=10
 
if Age < 20 then
     person="child"
else
     person="adult"
 
if Age==10
     begin
               x=50
          y=20
     end
 
// nested if/else
if Age <= 60
               if Age < 40
          call print("Under 40")
     // this else corresponds to the inner if statement
     else
 
          call print("Age 40 to 60")
// this else corresponds to the outer if statement
else
     call print("Over 60")

integer i
for i = 1 to 10 step 2
call print('Value of i is ' & i)
 
integer x
integer y
x=10 y=20
 
for i = x to y
     call print('Value of i is ' & i)
 
for i = y to x step -1
     begin
          call print('Value of i is ' & i)
          x=i /*does not affect the loop since start/end/step
          expressions are only evaluated before loop*/
     end

integer i
i=1000
// keep looping while the value of i is > 10
while i > 10 
     i=i/2
 
// you can use begin/end to enclose more than one statement 
while i < 1000
     begin
          i=i*2
          call print('Value if i is ' & i)
     end

a = qd + r and 0 ≤ r < | d |, where | d | denotes the absolute value of d

// correct statements to compare the value of x and y
if x==y then statement1
else statement2
 
// Assigning a value
x=y

string str 
// simple string
str="Hello"
// concatenate two strings
str="Hello" & " There"

integer x 
real r
 
// order of precedence starts with parentheses,
// then multiplication, then addition
x=1+(2+3)*4
 
// string is converted to value 10
x=5 + "10"
r=3.14 
 
// x will now be 3
x=r

date date_value1
date data_value2
date_value1 = todate("01/02/03")
date_value2 = #01-02-03#

boolean a
boolean b
boolean c
 
a=true
b=false
// c is true
c=a or b 
// c is false
c=a and b 
// c is true
c=10<20 
// c is false
c=10==20 
// c is true
c=10!=20 
// c is true
c='yes' 
// c is false
c='no'

integer x
integer y
integer z 
boolean b 
string s 
x=10 
y=null 
// z has a value of null
z=x + y 
// b is true
b=true or null
// b is null
b=false or null
// use isnull function to determine if null
if isnull(b) 
     call print("B is null")
// s is "str"
s="str" & null

toreal(xyz) > 123.456

string str
integer x 
str="Hello there"
// calls the upper function
if upper(str)=='HELLO THERE'
     // calls the print function
     call print("yes")
 
// x is set to 7 (position of word 'there')
x=instr(str,"there",1)

function example_udf return string 255
   // this function is declared to return a string of
   // up to 255 characters retrieve the number of
   // parameters passed
   print("You passed " & parametercount() & " parameters")
   integer x
   for x = 1 to parametercount()
   begin
      print("Parameter " & x & " type is " &
      parametertype(x) & " value is " & parameter(x))
      if(parametertype(x)=="integer")
         print("Integer: " & parameterinteger(x))
      else if parametertype(x)=="real"
         print("Real: " & parameterreal(x))
   end
   return "string val"
end function