Strictly convert string to integer (or nil)

Question

For web programming, numbers come in as strings. but to_i will convert \"5abc\" to 5 and \"abc\" to 0, both

Answer 1

Use a simple regex to check str is an integer.

def number_or_nil(str)
   str.to_i if str[/^-?\d+$/] and str.line.size == 1
end