def jp_zip2pref(zip)
pref = nil
case zip
when /^01/
pref = "秋田県"
when /^02/
pref = "岩手県"
when /^03/
pref = "青森県"
when /^0[4-9]/
pref = "北海道"
when /^1/
pref = "東京都"
when /^2[1-5]/
pref = "神奈川県"
when /^2[6-9]/
pref = "千葉県"
when /^3[0-1]/
pref = "茨城県"
when /^32/
pref = "栃木県"
when /^3[3-6]/
pref = "埼玉県"
when /^37/
pref = "群馬県"
when /^3[8-9]/
pref = "長野県"
when /^40/
pref = "山梨県"
when /^4[1-3]/
pref = "静岡県"
when /^4[4-9]/
pref = "愛知県"
when /^50/
pref = "岐阜県"
when /^51/
pref = "三重県"
when /^52/
pref = "滋賀県"
when /^5[3-9]/
pref = "大阪府"
when /^6[0-2]/
pref = "京都府"
when /^63/
pref = "奈良県"
when /^64/
pref = "和歌山県"
when /^6[5-7]/
pref = "兵庫県"
when /^68/
pref = "鳥取県"
when /^69/
pref = "島根県"
when /^7[0-1]/
pref = "岡山県"
when /^7[2-3]/
pref = "広島県"
when /^7[4-5]/
pref = "山口県"
when /^76/
pref = "香川県"
when /^77/
pref = "徳島県"
when /^78/
pref = "高知県"
when /^79/
pref = "愛媛県"
when /^8[03]/
pref = "福岡県"
when /^84/
pref = "佐賀県"
when /^8[15]/
pref = "長崎県"
when /^86/
pref = "熊本県"
when /^87/
pref = "大分県"
when /^88/
pref = "宮崎県"
when /^89/
pref = "鹿児島県"
when /^90/
pref = "沖縄県"
when /^91/
pref = "福井県"
when /^92/
pref = "石川県"
when /^93/
pref = "富山県"
when /^9[4-5]/
pref = "新潟県"
when /^96/
pref = "福島県"
when /^98/
pref = "宮城県"
when /^99/
pref = "山形県"
end
pref
end
puts jp_zip2pref("3340000")
puts jp_zip2pref("7450000")
puts jp_zip2pref("9500000")
puts jp_zip2pref("0000001")