if command allows commands to be executed conditionally.
if (<condition>) <command-line>
<condition> will be evaluated. If it is true (non-zero), then the command(s)
of the <command-line> will be executed. If <condition> is false (zero), then
the entire <command-line> is ignored. Note that use of
; to allow multiple
commands on the same line will _not_ end the conditionalized commands.
pi=3 if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi
?Fixing pi! 3.14159265358979
if (1==2) print "Never see this"; print "Or this either"
will not display anything.
reread for an example of how
reread can be used together to
perform a loop.