# Euphoria - Sequences

A sequence is represented by a list 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 we ask for x[2] we get {11,22,33} and if we ask for x[2][3] we 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\n", {a, x[a]}) end for

Here length() is a Euphoria's built-in function which returns length of the sequence. Above example would produce 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"""

Try 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\n", {a, x[a]}) end for

This would produce 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 string 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\n", {a, x[a]}) end for

This would produce 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\n", {employee[1][1],employee[1][2]} )

This would produce following result −

First Name = John, Last Name = Smith

There are following operations which can be performed directly on sequences −

## Urinary Operation

When applied to a sequence, a unary operator is actually applied 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\n", {a, x[a]}) end for

This would produce 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, "}\n") b = x - y puts(1, "Value of b = {") for i = 1 to length(a) do printf(1, "%d,", b[i]) end for puts(1, "}\n") c = x * 3 puts(1, "Value of c = {") for i = 1 to length(c) do printf(1, "%d,", c[i]) end for puts(1, "}\n")

This would produce 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 line options to a Euphoria script and it can be accessed as a sequence using **command_line()** function as follows −

#!/home/euphoria-4.0b2/bin/eui sequence x x = command_line() printf(1, "Interpeter Name: %s\n", {x[1]} ) printf(1, "Script Name: %s\n", {x[2]} ) printf(1, "First Argument: %s\n", {x[3]}) printf(1, "Second Argument: %s\n", {x[4]})

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

$eui test.ex "one" "two"

This would produce following result −

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