62 lines
1.6 KiB
Plaintext
62 lines
1.6 KiB
Plaintext
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'\"
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'\" Copyright (c) 1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH incr n "" Tcl "Tcl Built-In Commands"
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.so man.macros
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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incr \- Increment the value of a variable
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.SH SYNOPSIS
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\fBincr \fIvarName \fR?\fIincrement\fR?
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.BE
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.SH DESCRIPTION
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.PP
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Increments the value stored in the variable whose name is \fIvarName\fR.
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The value of the variable must be an integer.
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If \fIincrement\fR is supplied then its value (which must be an
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integer) is added to the value of variable \fIvarName\fR; otherwise
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1 is added to \fIvarName\fR.
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The new value is stored as a decimal string in variable \fIvarName\fR
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and also returned as result.
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.PP
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Starting with the Tcl 8.5 release, the variable \fIvarName\fR passed
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to \fBincr\fR may be unset, and in that case, it will be set to
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the value \fIincrement\fR or to the default increment value of \fB1\fR.
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.SH EXAMPLES
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.PP
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Add one to the contents of the variable \fIx\fR:
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.PP
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.CS
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\fBincr\fR x
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.CE
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.PP
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Add 42 to the contents of the variable \fIx\fR:
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.PP
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.CS
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\fBincr\fR x 42
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.CE
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.PP
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Add the contents of the variable \fIy\fR to the contents of the
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variable \fIx\fR:
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.PP
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.CS
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\fBincr\fR x $y
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.CE
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.PP
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Add nothing at all to the variable \fIx\fR (often useful for checking
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whether an argument to a procedure is actually integral and generating
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an error if it is not):
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.PP
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.CS
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\fBincr\fR x 0
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.CE
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.SH "SEE ALSO"
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expr(n), set(n)
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.SH KEYWORDS
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add, increment, variable, value
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