OpenEuphoria

2. Re: confused...

• Posted by achury Feb 03, 2009
• 936 views

The variable that receives this value must be declared as sequence or object, never as string. Please check this and post all the code.

4. Re: confused...

• Posted by mattlewis (admin) Feb 03, 2009
• 950 views

Could you post the code that you used? It sounds like you're trying to print the result, which is where I believe this error message would come from. You might try printing out using the question mark, or print instead of puts or printf.

Note that there are actually five different objects in the example:

1. 99: an integer
2. 5.2: an atom
3. {1,2,3}: a sequence
4. "Hello": a string of characters (which is actually identical to the sequence {72,101,108,108,111}
5. -1: an integer

Matt

6. Re: confused...

• Posted by Burt Feb 03, 2009
• 948 views

Hi Guillermo,

Yes, I think that was the problem, when I change the code (as Matt suggested) to:

include get.e 
sequence input 
puts(1, "enter some text ") 
input = get(0) 
if input[1] != 1 then 
   ? input[2] 
else 
   puts(1, "not a valid euphoria object!") 
end if 

There was no error message, but the output wasn't what I was expecting. In the manual it says:

Actually, I'm not entirely clear what a "valid" euphoria object is in this context! In the manual it says:

"Input, from file fn, a human-readable string of characters representing a Euphoria object."

Nor am I sure what "human readable" means...

So if I wanted to read in from the keyboard a list of numbers and or strings, would I need to use a loop? and if I wanted to print out what I'd input would I need to test the elements of the sequence to determine which was a string and which was a number. I have a feeling I'm making this more complicated than it actually is.

8. Re: confused...

• Posted by Burt Feb 03, 2009
• 935 views

For example, suppose I wanted to create a little database, so I type the following on one line:

nuts 1.20 bolts 3.30 washers 2.50 screws 1.50

Here is the code I wrote to do it:

include get.e 
sequence input 
puts(1, "enter the items\n") 
while 1 do 
   input = get(0) 
   if input[1] = 1 then 
      exit 
   end if 
end while 

But it's not working, nothing is going into input. Where have I gone wrong?

10. Re: confused...

• Posted by bryanso Feb 03, 2009
• 935 views

Dear Burt,

If you enter this as input:

nuts 1.20 bolts 3.30 washers 2.50 screws 1.50

Then it won't work because the above is not a Euphoria object. A euphoria object is like this:

{ 1 {23 2} "abc"}

You may try

"nuts" 1.20 "bolts" 3.30 "washers" ...

Then it will probably work. The first get() will get "nuts". The second get() will get 1.20 etc.

Bryan

12. Re: confused...

• Posted by DerekParnell (admin) Feb 03, 2009
• 983 views

Welcome to both programming and Euphoria. Glad to have you, and this is the place to ask questions.

Ok, there are a few things here.

• Yes, each call to get() will read one and only one object at a time. That object can be a number (integer or atom) or a sequence (which includes strings).
• Yes, strings are sequences.
• Yes, sequences can be nested.

However, the message you got "sequence found inside character string" did not come from the get() call, but from a puts() or printf() call. Those routines can only deal with strings.

A string is a certain type of sequence. It is a sequence that consists only of integers in the value range of 0 - 255, and thus must not have nested sequences.

In the example from the manual, it reads in

{23, {49, 57}, 0.5, -1, 99, 'A', "john"} 

which is a single sequence containing seven elements. To display this sequence, you cannot use puts() or printf() because it is not a string sequence - it contains subsequences and floating point numbers.

If you need to display this as is, it might be best to use the pretty_print() routine instead ...

pretty_print(1, data, {2}) 

It all depends on how you want to see the data.

This example shows you five objects whereas the other example showed you one object - a sequence.

It just means that when you display the file as-is on screen, you can read it - that it contains just ASCII characters - plain text.

This is opposed to machine-readable data which contains bytes that are not meant to be used as if they where ASCII characters, for example a program (executable) file.

Maybe ... it all depends on what you want to do and how you want to do it. One thing about programming is that you get to decide on how you want to do stuff.

If you want to get data from a keyboard, it means that you want a person to type it in - naturally, but this also implies that your program must allow for human-error. In other words, you can not, and must not, expect a person to always type the correct data in.

This is what makes programming a challenge.

I haven't got time just now to finish this discussion, but I'd use the gets() function to read in a whole line of text and then parse it to extract the data elements.

14. Re: confused...

• Posted by achury Feb 04, 2009
• 958 views

Sorry I'm confusing you more. Those are predefined data types, but you can define your own types.

16. Re: confused...

• Posted by Burt Feb 04, 2009
• 1002 views

Something in the manual that caught my eye is:

"Brace brackets are used to construct sequences out of a list of expressions. These expressions can be constant or evaluated at run-time. e.g."

{x+6, 9, y*w+2, sin(0.5)} 

So does this mean that a sequence can contain calls to arbitrary user-defined functions? I replaced sin(0.5) with a user-defined function "square".

sequence s 
integer x, y, w 
x = 1 
y = 2 
w = 3 
 
function square(atom x) 
   return x*x 
end function 
 
s = {x + 6, 9, y*w + 2, square(0.5)} 
? s[4] -- gives 0.25 

This is very cool. I think I'm hooked!