CODEWITHSUNDEEP
rubyarrays
user2684405
user2684405

Reputation: 71

Using Math Symbols Stored in an Array as a String

I'm very new to Ruby and I'm trying to use math symbols that are stored in an array as strings to perform math. This is for a Reverse Polish Notation calculator I'm working on. For example:

var = ['1','2','+']

I've puzzled through enough regular expressions to figure out how to differentiate numbers from non-numbers in an if statement, but I'm trying to figure out how I could make the following work to produce -1.

var[0]  var[2] var[1]   #=>   1 - 2

Does anyone know how to change the string '-' back into the math symbol?

Upvotes: 2

Views: 255

Answers (2)

Santhosh
Santhosh

Reputation: 29094

'1'.to_i.send('-', '2'.to_i)
# => -1

send calls the first argument as a method on the object, with the remaining arguments as parameters.

Upvotes: 4

Eamonn O'Brien-Strain
Eamonn O'Brien-Strain

Reputation: 3412

One way to do this is using the eval function

result = eval "#{var[0]} #{var[2]} #{var[1]}"

Upvotes: 1

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