2.1.2 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 )

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 last case permits to use the value of a char-option as a char-expression. The various char-options are listed in General options, Geometry options, Mesh options, Solver options, and Post-processing 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.