Scratch equals operator problems

Question

I am using scratch.mit.edu version 2.0 on the internet and writing a program to evaluate a postfix expression. As I iterate through the input string such as: "23+" (postfix) letter by letter using the letter..of...block, it works fine.

I then add a letter.. of.. block to identify a spacebar character so the user can insert blanks in the expression eg "2 3 +"

However, there seems no way to recognize a blank character. I tried

1) Lookahead = ""
2) Lookahead =' '  
3) Lookahead =''

None of which pick up that a space has been encountered.

Here is the project: https://scratch.mit.edu/projects/77653712/

Scimonster · Answer 1 · 2015-09-21T20:35:17.033

5

In Scratch, the box is the string literal - no quotes, unless you're looking for literal quotes. Just put a space in the box.

Just set it to check <(Lookahead) = [ ]>: (brackets are the symbol for the box)

(That black line is me pressing ctrl+a to highlight and show that it exists.)

edited Sep 21 '15 at 20:35

answered Sep 21 '15 at 15:45

Scimonster

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I tried typing in lookahead =[ ] and it did not pick up any spaces from the user using the spacebar. The same error occured/ – Timothy Lawman Sep 21 '15 at 16:32
I looked at what you did now. No brackets - just the space. Absolutely nothing else. The brackets in the post were my way of showing the syntax. – Scimonster Sep 21 '15 at 20:09
Yes just solved it and noticed you have added the same comment! – Timothy Lawman Sep 21 '15 at 20:31
I clarified the answer to make the intention clear. If it was you who downvoted, i would appreciate if you would undo that. – Scimonster Sep 21 '15 at 20:36

score 1 · Answer 2 · answered Sep 21 '15 at 20:30

1

OK, I have found the solution. There is no character to represent a blank. You simply press space bar once!

You can see the letter nextChar of blanks is an empty space but, you must add space using the spacebar for it to work!!

answered Sep 21 '15 at 20:30

Timothy Lawman

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Scratch equals operator problems

2 Answers2