C strings in a switch statement [duplicate]

Question

Possible Duplicate:
best way to switch on a string in C

What is the general approach that is being used for strings (c character arrays) together with a switch statement? I'm querying my database for currencies that are stored as

"USD"
"EUR"
"GBP"

and so on. Coming from a PHP background, I would simply do:

switch ($string) {
  case "USD":
   return "$";
   break;
  case "EUR":
   return "€";
   break;   
  case "GBP":
   return "£";
   break;
  default:
   return "$";
}

In C the case-value has to be an integer. How would I go about implementing something like that in C? Will I end up writing lots of strcmp's in a huge if/else block? Please also note that I cannot simply compare the first characters of the currencies as some (not in this example though) start with the same character.

Answer 1

One way would be defining an array of C strings, and use it as a definition of your ordering:

const char *currencies[] = {"USD", "GBP", "EUR"};

Now you can search currencies for your string, and use its index in a switch statement.

You can get fancy and - sort your strings, and use bsearch to find the index in O(LogN)

Answer 2

The right answer in many languages is an associative container of some kind; std::map in C++, for example. There's a C implementation of an associative array in Glib: see here. There are other libraries that have their own.