Euphoria - Sequences

A sequence is represented by a pst of objects in brace brackets { }, separated by commas. A sequence can contain both atoms and other sequences. For example −

{2, 3, 5, 7, 11, 13, 17, 19}
{1, 2, {3, 3, 3}, 4, {5, {6}}}
{{"Zara", "Ayan"}, 52389, 97.25}
{} -- the 0-element sequence

A single element of a sequence may be selected by giving the element number in square brackets. Element numbers start at 1.

For example, if x contains {5, 7.2, 9, 0.5, 13} then x[2] is 7.2.

Suppose x[2] contains {11,22,33}, Now if you ask for x[2] you get {11,22,33} and if you ask for x[2][3], you get the atom 33.

Example

#!/home/euphoria-4.0b2/bin/eui

sequence x
x = {1, 2, 3, 4}

for a = 1 to length(x) do
   printf(1, "value of x[%d] = %d
", {a, x[a]})
end for

Here, length() is the built-in function which returns length of the sequence. The above example produces the following result −

value of x[1] = 1
value of x[2] = 2
value of x[3] = 3
value of x[4] = 4

Character String

A character string is just a sequence of characters. It may be entered in one of the two ways −

(a) Using Double Quotes −

"ABCDEFG"

(b) Using Raw String Notation −

-- Using back-quotes
`ABCDEFG`

or

-- Using three double-quotes
"""ABCDEFG"""

You can try the following example to understand the concept −

#!/home/euphoria-4.0b2/bin/eui

sequence x
x = "ABCD"

for a = 1 to length(x) do
   printf(1, "value of x[%d] = %s
", {a, x[a]})
end for

This produces the following result −

value of x[1] = A
value of x[2] = B
value of x[3] = C
value of x[4] = D

String Arrays

An array of strings can be implemented using Sequences as follows −

#!/home/euphoria-4.0b2/bin/eui

sequence x = {"Hello", "World", "Euphoria", "", "Last One"}

for a = 1 to length(x) do
   printf(1, "value of x[%d] = %s
", {a, x[a]})
end for

This produces the following result −

value of x[1] = Hello
value of x[2] = World
value of x[3] = Euphoria
value of x[4] =
value of x[5] = Last One

Euphoria Structures

A structure can be implemented using Sequences as follows −

#!/home/euphoria-4.0b2/bin/eui

sequence employee = {
   {"John","Smith"},
      45000,
      27,
      185.5
}
printf(1, "First Name = %s, Last Name = %s
", {employee[1][1],employee[1][2]} )

This produces the following result −

First Name = John, Last Name = Smith

There are various operations which can be performed directly on sequences. Let us see them in detail −

Urinary Operation

When appped to a sequence, a unary operator is actually appped to each element in the sequence to yield a sequence of results of the same length.

#!/home/euphoria-4.0b2/bin/eui

sequence x
x = -{1, 2, 3, 4}

for a = 1 to length(x) do
   printf(1, "value of x[%d] = %d
", {a, x[a]})
end for

This produces the following result −

value of x[1] = -1
value of x[2] = -2
value of x[3] = -3
value of x[4] = -4

Arithmetic Operations

Almost all arithmetic operations can be performed on sequences as follows −

#!/home/euphoria-4.0b2/bin/eui

sequence x, y, a, b, c
x = {1, 2, 3}
y = {10, 20, 30}

a = x + y
puts(1, "Value of a = {")

for i = 1 to length(a) do
   printf(1, "%d,", a[i])
end for
puts(1, "}
")

b = x - y
puts(1, "Value of b = {")
for i = 1 to length(a) do
   printf(1, "%d,", b[i])
end for
puts(1, "}
")

c = x * 3
puts(1, "Value of c = {")

for i = 1 to length(c) do
   printf(1, "%d,", c[i])
end for
puts(1, "}
")

This produces the following result −

Value of a = {11,22,33,}
Value of b = {-9,-18,-27,}
Value of c = {3,6,9,}

Command Line Options

A user can pass command pne options to a Euphoria script and it can be accessed as a sequence using command_pne() function as follows −

#!/home/euphoria-4.0b2/bin/eui

sequence x

x = command_pne()

printf(1, "Interpeter Name: %s
", {x[1]} )
printf(1, "Script Name: %s
", {x[2]} )
printf(1, "First Argument: %s
", {x[3]})
printf(1, "Second Argument: %s
", {x[4]})

Here printf() is Euphoria s built-in function. Now if you run this script as follows −

$eui test.ex "one" "two"

This produces the following result −

Interpeter Name: /home/euphoria-4.0b2/bin/eui
Script Name: test.ex
First Argument: one
Second Argument: two