Programming Interviews Exposed: Secrets to Landing Your Next Job, 3rd Edition

Strings

Strings are sequences of characters. However, what constitutes a character depends greatly on the language used and the settings of the operating system on which the application runs. Gone are the days when you could assume each character in a string is represented by a single byte. Multibyte encodings (either fixed length or variable length) of Unicode are needed to accurately store text in today’s global economy.

More recently designed languages, such as Java and C#, have a multibyte fundamental character type, whereas a char in C and C++ is always a single byte. (Recent versions of C and C++ also define a character type wchar_t, which is usually multibyte.) Even with built-in multibyte character types, properly handling all cases of Unicode can be tricky: There are more than 100,000 code points (representation-independent character definitions) defined in Unicode, so they can’t all be represented with a single, 2-byte Java or C# char. This problem is typically solved using variable length encodings, which use sequences of more than one fundamental character type to represent some code points.

One such encoding is UTF-16, used to encode strings in Java and C#. UTF-16 represents most of the commonly used Unicode code points in a single 16-bit char and uses two 16-bit chars to represent the remainder. UTF-8, another common encoding, is frequently used for text stored in files or transmitted across networks. UTF-8 uses one to four 8-bit chars to encode all Unicode code ...