[Newbies] Why the variable "a" is different out of the loop when codes are executed as a whole or by two steps?

RedTigerFish chihuyu at gmail.com
Sat Nov 18 07:36:26 UTC 2017





Hello, friends. 

This problem which confuses me comes from a  question
<http://forum.world.st/quot-Print-specific-integers-quot-Error-message-how-to-improve-and-what-causes-that-td5025067.html> 
I asked in "Squeak - Beginners" days ago.  

These are some special integers: myArray := #(2 32 44 67 89 111 123)
These special integers need to be specially labelled from integer 1 to 130. 
The rest normal numbers which myArray doesn't include will be printed also. 

Here's the code:

*|a n myArray| 

myArray := #(2 32 44 67 89 111 123). 

n := 1. 
a := myArray at: n. 

1 to: 130 do: [:i| 
        i = a 
        ifTrue: [ 
             Transcript show: ('Special number:  i = {1}, a = {2}' format:
{i. a}).
		 Transcript cr.
                n := n + 1. 	 
		    n = 8 
		   ifTrue: [a := 'I am no longer a number'.]
		   ifFalse: [a := myArray at: n. ].      
                ]
	  ifFalse: [
	           Transcript show: ('i = {1}, a = {2}' format: {i. a}).
	           Transcript  cr.
		      ].
        ]. 


Transcript show: a; cr.     'Last line'
*

Now comes something that makes my head big.

If I choose everything and do them, the last line, which should tell me what
a is when program jumps out of the loop, exactly shows that a is "I am no
longer a number".

However, if I choose everything except the last line, and do them. After
that, I do the last line. The output is nil. 

Why is a nil ?   Why's that?   

In order to make my question explicit, I recorded a video:

https://www.youtube.com/watch?v=pUQAEO4uSpk



-----
Dig, dig where you are,
Down below's well.
Let those that walk in darkness shout, 
Down below's hell.
--
Sent from: http://forum.world.st/Squeak-Beginners-f107673.html


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