4.2.2 Character expressions

Character expressions are defined as:

char-expression:
  "string" |
  Today |
  StrPrefix ( char-expression ) |
  StrRelative ( char-expression ) |
  StrCat ( char-expression , char-expression ) |
  Sprintf ( char-expression , expression-list ) |
  Sprintf ( char-expression ) |
  Sprintf ( char-option ) |
  GetEnv ( char-expression ) |
  GetString ( char-expression , char-expression )

The third and fourth cases in this definition permit to take the prefix (e.g. to remove the extension) or the relative path of a string. The fifth case permits to concatenate two character expressions, and the sixth and seventh are equivalent to the sprintf C function (where char-expression is a format string that can contain floating point formatting characters: %e, %g, etc.). The eigth case permits to use the value of a char-option as a char-expression. The ninth case gets the value of an environment variable from the operating system. The last case in the definition allows to ask the user for a value interactively. The various char-options are listed in Options.

Character expressions are mostly used to specify non-numeric options and input/output file names. See ‘t8.geo’, for an interesting usage of char-expressions in an animation script.

This document was generated on June 20, 2012 using texi2html 5.0.