regex on socrates exercise

regexsocratesexercisee.rb

# Determine whether a string contains a Social Security number.
def has_ssn?(string)
if string.scan(/\d\d\d.\d\d.\d\d\d\d/)[0] == nil
false
elsif string.scan(/\d\d\d.\d\d.\d\d\d\d/)[0] != nil
true
end
end

# Return the Social Security number from a string.
def grab_ssn(string)
string.scan(/\d\d\d.\d\d.\d\d\d\d/)[0]
end

# Return all of the Social Security numbers from a string.
def grab_all_ssns(string)
string.scan(/\d\d\d.\d\d.\d\d\d\d/)
end

# Obfuscate all of the Social Security numbers in a string. Example: XXX-XX-4430.
def hide_all_ssns(string)
string.gsub(/\d\d\d-\d\d/, "XXX-XX")
end

# Ensure all of the Social Security numbers use dashes for delimiters.
# Example: 480.01.4430 and 480014430 would both be 480-01-4430.
def format_ssns(string)
string.match(/\d{3}.\d{2}.\d{4}|\d{9}/) ? string.gsub(/(\d{3})(\d{2})(\d{4})/, "\\1-\\2-\\3").gsub(".", "-") : string 
end