说明：  We often need to use static data in our programs. By static, I mean our programs do not modify the data. For example, we can insert the list of the 50 US state names into a combobox so that the user can select his/her state using a mouse. The same goes with the names of months, the names of weekdays, etc. On other occasions, we need to "translate" between two different lists of static data. Say, we have to find the full name of a US state, given a two-character code, we may also have to find the corresponding name of the month, given a numeric value between 1 and 12
(We often need to use static data in our programs. By static, I mean our programs do not modify the data. For example, we can insert the list of the 50 US state names into a combobox so that the user can select his/her state using a mouse. The same goes with the names of months, the names of weekdays, etc. On other occasions, we need to translate between two different lists of static data. Say, we have to find the full name of a US state, given a two-character code, we may also have to find the corresponding name of the month, given a numeric value between 1 and 12)