Case sensitivity

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Text sometimes exhibits case sensitivity; that is, words can differ in meaning based on differing use of uppercase and lowercase letters. Words with capital letters do not always have the same meaning when written with lowercase letters. For example, Bill is the first name of former U.S. president William Clinton, who could sign a bill (which is a proposed law that was approved by Congress). And a Polish person can use polish to clean or shine something. In food, the Calorie, with a capital C, is sometimes used to denote 1000 calories of energy.

The opposite term of "case-sensitive" is "case-insensitive".

With computer systems

In computers, some examples of usually case-sensitive data are:

Some computer languages are case-sensitive (Java, C++, C#, C,Verilog, [1] Ruby[2] and XML). Others are case-insensitive (i.e., not case-sensitive), such as most BASICs (an exception being BBC BASIC), Fortran, SQL[3] and Pascal. There are also languages, such as Haskell, Prolog and Go, in which the capitalization of an identifier encodes information about its semantics.

Case-insensitive operations are sometimes said to fold case, from the idea of folding the character code table so that upper- and lower-case letters coincide. The alternative smash case is more likely to be used by someone that considers this behaviour a misfeature or in cases wherein one case is actually permanently converted to the other.

In Unix filesystems, filenames are usually case-sensitive. Old Windows filesystems (VFAT, FAT32) are not case-sensitive (there cannot be a readme.txt and a Readme.txt in the same folder) but are case-preserving, i.e. remembering the case of the letters. The original FAT12 filesystem was case-insensitive.[4] Current Windows file systems, like NTFS, are case-sensitive, that is you can have a readme.txt and a Readme.txt in the same folder, however, Windows disallows you to create a second file differing only in case.[5].

References

  1. ^ Kernighan, Brian W. (1978). "Chapter 2: Types, Operators and Expressions". The C Programming Language (1st ed.). Englewood Cliffs, NJ: Prentice Hall. p. 33. ISBN 0-13-110163-3. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  2. ^ Matsumoto, Yukihiro (2002). "Chapter 2: Language Basics". Ruby in a nutshell (1st ed.). O'Reilly Media. p. 9. ISBN 0-596-00214-9. {{cite book}}: Unknown parameter |month= ignored (help)
  3. ^ Although one can explicitly set a single database or column collation to be case-sensitive
  4. ^ http://technet.microsoft.com/en-us/library/cc739978(v=ws.10).aspx
  5. ^ http://support.microsoft.com/kb/100625

External links