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 ) |
  Str ( char-expression , … ) |
  Sprintf ( char-expression , expression-list ) |
  Sprintf ( char-expression ) |
  Sprintf ( char-option ) |
  GetEnv ( char-expression ) |
  GetString ( char-expression , char-expression ) | 
  StrReplace ( char-expression , char-expression , char-expression ) 

StrPrefix and StrRelative permit to take the prefix (e.g. to remove the extension) or the relative path of a file name. StrCat and Str permit to concatenate character expressions (Str adds a newline character after each string except the last). Sprintf is equivalent to the sprintf C function (where char-expression is a format string that can contain floating point formatting characters: %e, %g, etc.) The various char-options are listed in Options. GetEnvThe gets the value of an environment variable from the operating system. GetString allows to ask the user for a value interactively. StrReplace’s arguments are: input string, old substring, new substring.(4)

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.

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