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 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\n", {a, x[a]})
end for
Here, length() is the built-in function that returns the 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\n", {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\n", {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\n", {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 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 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, "}\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 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-line options to a Euphoria script and it can be accessed as a sequence using the 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 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
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