set(3tcl) Tcl Built-In Commands set(3tcl)
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NAME
set - Read and write variables
SYNOPSIS
set varName ?value?
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DESCRIPTION
Returns the value of variable varName. If value is specified, then set
the value of varName to value, creating a new variable if one does not
already exist, and return its value. If varName contains an open
parenthesis and ends with a close parenthesis, then it refers to an ar-
ray element: the characters before the first open parenthesis are the
name of the array, and the characters between the parentheses are the
index within the array. Otherwise varName refers to a scalar variable.
If varName includes namespace qualifiers (in the array name if it
refers to an array element), or if varName is unqualified (does not in-
clude the names of any containing namespaces) but no procedure is ac-
tive, varName refers to a namespace variable resolved according to the
rules described under NAME RESOLUTION in the namespace manual page.
If a procedure is active and varName is unqualified, then varName
refers to a parameter or local variable of the procedure, unless var-
Name was declared to resolve differently through one of the global,
variable or upvar commands.
EXAMPLES
Store a random number in the variable r:
set r [expr {rand()}]
Store a short message in an array element:
set anAry(msg) "Hello, World!"
Store a short message in an array element specified by a variable:
set elemName "msg"
set anAry($elemName) "Hello, World!"
Copy a value into the variable out from a variable whose name is stored
in the vbl (note that it is often easier to use arrays in practice in-
stead of doing double-dereferencing):
set in0 "small random"
set in1 "large random"
set vbl in[expr {rand() >= 0.5}]
set out [set $vbl]
SEE ALSO
expr(3tcl), global(3tcl), namespace(3tcl), proc(3tcl), trace(3tcl), un-
set(3tcl), upvar(3tcl), variable(3tcl)
KEYWORDS
read, write, variable
Tcl set(3tcl)
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