Question

I need to convert a mixed number to float type, for eg: 1 1/2 to 1.5.

Is there any built in method in ruby to achieve the same?

Answer 1

You could split into pieces, convert the pieces to Rationals, sum the Rationals, and convert the result to a Float:

s = '1 1/2'
f = s.split.map { |r| Rational(r) }.inject(:+).to_f
# 1.5

If you know that the string will always have two parts then you could handle the pieces separately:

s = '1 1/2'
a = s.split
f = a.first.to_i + Rational(a.last).to_f
# 1.5

If you’re not sure how many parts there will be (i.e. '1', '3/2', '11 23/42', … are all possible) then the first one should work in all cases.

Kernel#Rational will raise an ArgumentError if it can’t parse the string so you might want to wrap the whole thing in a begin/except block to deal with errors.