NAME
       incr - Increment the value of a variable

SYNOPSIS
       incr varName ?increment?


DESCRIPTION
       Increments the value stored in the variable whose name is varName.  The
       value of the variable must be an integer.   If  increment  is  supplied
       then  its  value  (which  must  be an integer) is added to the value of
       variable varName;  otherwise 1 is added to varName.  The new  value  is
       stored  as  a  decimal  string in variable varName and also returned as
       result.

EXAMPLES
       Add one to the contents of the variable x:
              incr x

       Add 42 to the contents of the variable x:
              incr x 42

       Add the contents of the variable y to the contents of the variable x:
              incr x $y

       Add nothing at all to the variable x (often useful for checking whether
       an  argument to a procedure is actually numeric and generating an error
       if it is not):
              incr x 0


SEE ALSO
       expr(n)


KEYWORDS
