5.6.1 Setting Registers
Define or set registers using the `nr' request or the `\R' escape.
-- Request: .nr ident value
-- Escape: \R'ident value'
Set number register IDENT to VALUE. If IDENT doesn't exist,
`gtroff' creates it.
The argument to `\R' usually has to be enclosed in quotes. Note:
Escapes, for details on parameter delimiting characters.
The `\R' escape doesn't produce an input token in `gtroff'; in
other words, it vanishes completely after `gtroff' has processed
For example, the following two lines are equivalent:
.nr a (((17 + (3 * 4))) % 4)
\R'a (((17 + (3 * 4))) % 4)'
Both `nr' and `\R' have two additional special forms to increment or
decrement a register.
-- Request: .nr ident +value
-- Request: .nr ident -value
-- Escape: \R'ident +value'
-- Escape: \R'ident -value'
Increment (decrement) register IDENT by VALUE.
.nr a 1
.nr a +1
To assign the negated value of a register to another register,
some care must be taken to get the desired result:
.nr a 7
.nr b 3
.nr a -\nb
.nr a (-\nb)
The surrounding parentheses prevent the interpretation of the
minus sign as a decrementing operator. An alternative is to start
the assignment with a `0':
.nr a 7
.nr b -3
.nr a \nb
.nr a 0\nb
-- Request: .rr ident
Remove number register IDENT. If IDENT doesn't exist, the request
-- Request: .rnn ident1 ident2
Rename number register IDENT1 to IDENT2. If either IDENT1 or
IDENT2 doesn't exist, the request is ignored.
-- Request: .aln ident1 ident2
Create an alias IDENT1 for a number register IDENT2. The new name
and the old name are exactly equivalent. If IDENT1 is undefined,
a warning of type `reg' is generated, and the request is ignored.
Note: Debugging, for information about warnings.
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