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35.Dd $Mdocdate: September 5 2017 $
36.Dt ISUPPER 3
37.Os
38.Sh NAME
39.Nm isupper ,
40.Nm isupper_l
41.Nd upper-case singly-byte character test
42.Sh SYNOPSIS
43.In ctype.h
44.Ft int
45.Fn isupper "int c"
46.Ft int
47.Fn isupper_l "int c" "locale_t locale"
48.Sh DESCRIPTION
49The
50.Fn isupper
51and
52.Fn isupper_l
53functions test whether
54.Fa c
55represents an upper-case letter.
56.Pp
57In the C locale, the complete list of upper-case letters is A\(enZ.
58.Ox
59always uses the C locale for these functions,
60ignoring the global locale, the thread-specific locale, and the
61.Fa locale
62argument.
63.Sh RETURN VALUES
64These functions return zero if the character tests false or
65non-zero if the character tests true.
66.Sh ENVIRONMENT
67On systems supporting non-ASCII single-byte character encodings,
68these functions may return non-zero for additional characters,
69and the results of
70.Fn isupper
71may depend on the
72.Ev LC_CTYPE
73.Xr locale 1 ,
74but they never return non-zero for any character for which
75.Xr iscntrl 3 ,
76.Xr isdigit 3 ,
77.Xr ispunct 3 ,
78or
79.Xr isspace 3
80is true.
81.Sh SEE ALSO
82.Xr isalnum 3 ,
83.Xr isalpha 3 ,
84.Xr isascii 3 ,
85.Xr isblank 3 ,
86.Xr iscntrl 3 ,
87.Xr isdigit 3 ,
88.Xr isgraph 3 ,
89.Xr islower 3 ,
90.Xr isprint 3 ,
91.Xr ispunct 3 ,
92.Xr isspace 3 ,
93.Xr iswupper 3 ,
94.Xr isxdigit 3 ,
95.Xr stdio 3 ,
96.Xr toascii 3 ,
97.Xr tolower 3 ,
98.Xr toupper 3 ,
99.Xr ascii 7
100.Sh STANDARDS
101The
102.Fn isupper
103function conforms to
104.St -ansiC ,
105and
106.Fn isupper_l
107to
108.St -p1003.1-2008 .
109.Sh HISTORY
110The
111.Fn isupper
112function first appeared in
113.At v7 ,
114and
115.Fn isupper_l
116has been available since
117.Ox 6.2 .
118.Sh CAVEATS
119The argument
120.Fa c
121must be
122.Dv EOF
123or representable as an
124.Li unsigned char ;
125otherwise, the result is undefined.
126