OpenEuphoria

1. General Beginner Issues

• Posted by Kirkkaf13 Jul 15, 2013
• 3159 views

Hello everyone,

Sorry I couldn't be more specific with the title I have a range of queries/issues.

[1]First of all I am a little confused after reading the documentation on atoms and sequences, as these are the only data objects in Euphoria.

As I understand these vary from memory allocated the update as needed. Then I came across the normal integer data type, so now I have a choice between using an atom or integer? I must of misunderstood the documentation.

[2]If I run the following example; EDITED I think it was something to do with puts (I thought this was the same as print).

puts(1, "Hello, World\n")

As expected I get the words "Hello World" printed within the console. Now I attempted to do the same with a simple calculation;

integer x = 2
puts(1, x+x)

I get a symbol within the console and not the calculated answer, what am I doing wrong?

[3]Can someone explain how I can declare a string variable, is this using sequence?

Thank you for your time and I apologise if my questions are very basic.

Kirk

3. Re: General Beginner Issues

• Posted by jaygade Jul 15, 2013
• 3153 views

Integers are a special case of atom -- technically, all integers are also atoms. They are included mainly for performance reasons, because most computers still work more quickly with whole numbers rather than with fractional numbers.

You can write all of your programs to use "atom" instead of "integer" if you want, and you will probably still get the results you expect. Reference: http://openeuphoria.org/docs/intro.html#_7_euphoriaisunique

puts(1, "Hello, World\n")

integer x = 2
puts(1, x+x)

Euphoria has a lot of output routines. The built-in ones such as puts and printf are probably more familiar to people who have been programming for awhile; however for beginners it's probably best to use writef and writefln from std/io.e:

include std/io.e -- required for the writef and writefln function definitions 
 
integer x = 2 
writefln("[]", {x}) -- it's okay to skip the {} for a single value, but it's good practice. 

Formatted output can get pretty complex, but with that complexity comes great flexibility. Reference: http://openeuphoria.org/docs/std_io.html#_1777_writefln

See also http://openeuphoria.org/docs/std_io.html#_1579_printf for more traditional C-style formatted output.

5. Re: General Beginner Issues

• Posted by DerekParnell (admin) Jul 16, 2013
• 3148 views

Not a problem. It can be a bit confusing at first, especially if you've had experience with other programming languages.

Ok ... while it is true that there are only two data types, atoms and sequences, there are also two 'helper' data types.

An integer is just a specialized atom and can be used where your application needs a bit of extra speed and only in situations where whole numbers are expected.

An object is a variable that can hold anything, and this can change during the running of your program. That is, you can assign a sequence to an object, then later on assign an atom to the same object.

Also note that a sequence is an array of objects. This means that any element in a sequence can hold an atom or a sequence. This is how we get nested sequences and build complex data structures.

puts(1, "Hello, World\n")

integer x = 2
puts(1, x+x)

puts stands for "Put String". It is designed to output the 'string' you supply. If you supply a number (atom or integer), it first converts it to an integer in the range 0 - 255, and then assumes that the resulting number is the ASCII code for a single character. So it outputs one character.

A string is a sequence containing only integer values. Each integer is the code for a character. By default, only ASCII codes are currently supported.

Note that as a convenience, literal strings can be used in source code as double-quoted character strings.

sequence Str 
 
Str = "abc"  -- A string 
Str[2] = 3.142 -- No longer is it a string because the second element is no longer an integer. 
 
Str[2] = 65  -- Back to being a string (changes the 2nd element to an integer) 
 
Str[3] = "def" -- No longer a string because the 3rd element is now a sequence.  
 

7. Re: General Beginner Issues

• Posted by _tom (admin) Jul 16, 2013
• 3003 views

I have added a tutorial to the wiki showing how Euphoria can be programmed with just one data-type. The tutorial theme is: how programming with objects is possible, how Euphoria converts all data into numbers, and how objects are output.

Understanding how an object works should help people coming from a conventional programming background.

The wiki link is: http://openeuphoria.org/wiki/view/The%20All%20Mighty%20Object.wc

TOM

9. Re: General Beginner Issues

• Posted by andi49 Jul 16, 2013
• 2962 views

Wow, thank you, Great job
Andreas

11. Re: General Beginner Issues

• Posted by _tom (admin) Jul 16, 2013
• 2992 views

Thank you for the encouragement.

It looks like I can include this tutorial in the next official Euphoria documentation.

Thanks

TOM

13. Re: General Beginner Issues

• Posted by useless_ Jul 16, 2013
• 2989 views

Very good, Tom.

useless-kat