Item 2. Case-Insensitive Strings—Part 1

Difficulty: 7

So you want a case-insensitive string class? Your mission, should you choose to accept it, is to write one.

This Item is composed of three related points.

1. What does "case-insensitive" mean?

2. Write a ci_string class that is identical to the standard std::string class but that is case-insensitive in the same way as the commonly provided extension stricmp().^[1] A ci_string should be usable as follows:

   ^[1] The stricmp() case-insensitive string comparison function is not part of the C or C++ standards, but it is a common extension on many C and C++ compilers.

   ci_string s( "AbCdE" ); 
   // case insensitive
   //
   assert( s == "abcde" );
   assert( s == "ABCDE" );
   // still case-preserving, of course
   //
   assert( strcmp( s.c_str(), "AbCdE" ) == 0 );
   assert( strcmp( s.c_str(), "abcde" ) != 0 );
   

3. Is making case sensitivity a property of the object a good idea?