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:
Add 42 to the contents of the variable x:
incr x 42
Add the contents of the variable y to the contents of the
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
add, increment, variable, value
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Copyright © 1994-1996 Sun Microsystems, Inc.