If

The if command allows commands to be executed conditionally.

Syntax:

     if (<condition>) <command-line> [; else if (<condition>) ...; else ...]

5#5condition6#6 will be evaluated. If it is true (non-zero), then the command(s) of the 5#5command-line6#6 will be executed. If 5#5condition6#6 is false (zero), then the entire 5#5command-line6#6 is ignored until the next occurrence of else. Note that use of ; to allow multiple commands on the same line will not end the conditionalized commands.

Examples:

     pi=3
     if (pi!=acos(-1)) print "?Fixing pi!"; pi=acos(-1); print pi

will display:

     ?Fixing pi!
     3.14159265358979

but

     if (1==2) print "Never see this"; print "Or this either"

will not display anything.

else:

     v=0
     v=v+1; if (v%2) print "2" ; else if (v%3) print "3"; else print "fred"

(repeat the last line repeatedly!)

See reread (p. ) for an example of how if (p. ) and reread (p. ) can be used together to perform a loop.