conv.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 104 行

.\" SCCSID: @(#)atof.3	2.5	8/10/87
.TH conv 3 
.SH Name
toupper, tolower, _toupper, _tolower, toascii \- translate characters
.SH Syntax
.nf
.B #include <ctype.h>
.PP
.B int toupper(\fIc\fP)
.B int c;
.PP
.B int tolower(\fIc\fP)
.B int c;
.PP
.B int _toupper(\fIc\fP)
.B int c;
.PP
.B int _tolower(\fIc\fP)
.B int c;
.PP
.B int toascii(\fIc\fP)
.B int c;
.fi
.SH Description
.NXR "tolower subroutine (standard C)"
.NXR "toupper subroutine"
.NXR "_toupper subroutine"
.NXR "_tolower subroutine"
.NXR "toacsii  subroutine"
The functions
.PN toupper 
and
.PN tolower
have as their domain the range of the 
.PN getc
function. If the argument to
.PN toupper
represents a lowercase letter, the output from the function is the corresponding
uppercase letter. If the argument to
.PN tolower 
represents an uppercase letter, the result is the corresponding lowercase letter.
.PP
The case of 
.I c 
depends on the definition of the character in the language database. Because
the case of a character can vary between language databases, the case of 
.I c 
depends on what language database is in use. Specifically, the case of arguments
depends on what property tables are associated the LC_CTYPE category.
Property tables are associated with the LC_CTYPE category by a successful call to
the 
.PN setlocale
function that includes the LC_CTYPE category. If no successful call to define
LC_CTYPE has occurred or if the character case information is unavailable for the
language in use, the rules of the ASCII coded character set determine the case 
of arguments.
.PP
If the argument to the
.PN toupper
function does not have the uppercase attribute, 
.PN toupper 
returns the argument unchanged.  Likewise, if the argument to the
.PN tolower
function does not have the lowercase attribute, 
.PN tolower
returns it unchanged.
.PP
The macros
.PN _toupper
and 
.PN _tolower
have the same affect as 
.PN toupper
and 
.PN tolower .
The difference is that the argument to the macros must be an ASCII character
(that is, a character in the domain \-1 to 127) and the argument must have the
appropriate case.  Arguments to 
.PN _toupper 
must have the uppercase attribute and arguments to
.PN _tolower 
must the lowercase attribute. The result of supplying arguments to these macros 
that are outside the domain or do not have the appropriate case is undefined.
These macros operate faster than the 
.PN toupper
and 
.PN tolower
functions.
.PP
The macro
.PN toascii
converts its argument to the ASCII character set. The macro converts its 
argument by truncating the numerical representation of the argument so that 
it is between \-1 and 127. You can use this macro when you move an application
to a system other than an ULTRIX system.
.SS International Environment
.IP LC_CTYPE 15
If this environment variable is set and valid,
.PN conv
uses the international language database named in the definition to
determine character classification rules.
.SH See Also
ctype(3int), setlocale(3), getc(3)