incr — Increment the value of a variable
incr varName ?increment?
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.
Starting with the Tcl 8.5 release, the variable varName
passed to incr may be unset, and in that case, it will be
set to the value increment or to the default increment value
of 1.
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 integral
and generating an error if it is not):
incr x 0
expr, set
add, increment, variable, value
Copyright © 1993 The Regents of the University of
California.
Copyright © 1994-1996 Sun Microsystems, Inc.