xref: /freebsd/lib/libc/string/index.3 (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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30.\"     @(#)index.3	8.1 (Berkeley) 6/4/93
31.\" $FreeBSD$
32.\"
33.Dd June 4, 1993
34.Dt INDEX 3
35.Os
36.Sh NAME
37.Nm index , rindex
38.Nd locate character in string
39.Sh LIBRARY
40.Lb libc
41.Sh SYNOPSIS
42.In strings.h
43.Ft "char *"
44.Fn index "const char *s" "int c"
45.Ft "char *"
46.Fn rindex "const char *s" "int c"
47.Sh DESCRIPTION
48The
49.Fn index
50function
51locates the first occurrence of
52.Fa c
53(converted to a
54.Vt char )
55in the string pointed to by
56.Fa s .
57The terminating null character is considered part of the string;
58therefore if
59.Fa c
60is
61.Ql \e0 ,
62the functions locate the terminating
63.Ql \e0 .
64.Pp
65The
66.Fn rindex
67function is identical to
68.Fn index ,
69except it locates the last occurrence of
70.Fa c .
71.Sh RETURN VALUES
72The functions
73.Fn index
74and
75.Fn rindex
76return a pointer to the located character, or
77.Dv NULL
78if the character does not appear in the string.
79.Sh SEE ALSO
80.Xr memchr 3 ,
81.Xr strchr 3 ,
82.Xr strcspn 3 ,
83.Xr strpbrk 3 ,
84.Xr strrchr 3 ,
85.Xr strsep 3 ,
86.Xr strspn 3 ,
87.Xr strstr 3 ,
88.Xr strtok 3
89.Sh HISTORY
90The
91.Fn index
92and
93.Fn rindex
94functions appeared in
95.At v6 .
96Their prototypes existed previously in
97.In string.h
98before they were moved to
99.In strings.h
100for
101.St -p1003.1-2001
102compliance.
103