MOLPRO

8 VARIABLES 47
8.3 String variables
As explained already in section 8.1, string variables can be set as other variables in the form
variable = ’string’
variable = string variable
Strings must be enclosed by quotes. Otherwise the string is assumed to be a variable, and if this
is undefined it is assumed to be zero.
Alternatively, if the name of the variable is preceded by a dollar ($), all values is assumed to be
a string. This can a string variable, a quoted string, or an unquoted string. Note that unquoted
strings are converted to upper case. Also note that quotes are compulsory if the string contains
blanks.
Example:
$str=[a,b+4,’This is an example for strings’]
yields
STR(1) = A
STR(2) = B+4
STR(3) = This is an example for strings
As a general rule, string variables are replaced by their value only if they are preceded by a
dollar ($) (exceptions: in variable definitions, on SHOW cards, and in logical expressions on IF
cards, the dollar is optional). This is a precaution to avoid commands which have the same name
as a variable being interpreted as variables. Variables may also appear on TEXT or TITLE cards
or in strings, but must be preceded by $ in these cases. Example:
$METHOD=MCSCF
R=1.5
TEXT,$method results for R=$R Bohr
prints
MCSCF results for R=1.5 Bohr
String variables can be concatenated with strings or other string variables in the following way.
Assume that variable PROGRAM has the value MRCI. Setting
METHOD=’$PROGRAM+Q’
sets METHOD to MRCI+Q. Alternatively, if we would also have a variable VERSION with value
Q, we could write
METHOD=’$PROGRAM+$VERSION’
Again, the value of METHOD would be MRCI+Q. Note that the quotes are necessary in these
cases.
Substring operations are not implemented.