xref: /dragonfly/lib/libc/string/strcpy.3 (revision 0bb9290e) 
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36.\"     @(#)strcpy.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD: src/lib/libc/string/strcpy.3,v 1.4.2.5 2001/12/14 18:33:59 ru Exp $
38.\" $DragonFly: src/lib/libc/string/strcpy.3,v 1.3 2005/08/05 22:35:10 swildner Exp $
39.\"
40.Dd August 9, 2001
41.Dt STRCPY 3
42.Os
43.Sh NAME
44.Nm strcpy ,
45.Nm strncpy
46.Nd copy strings
47.Sh LIBRARY
48.Lb libc
49.Sh SYNOPSIS
50.In string.h
51.Ft char *
52.Fn strcpy "char *dst" "const char *src"
53.Ft char *
54.Fn strncpy "char *dst" "const char *src" "size_t len"
55.Sh DESCRIPTION
56The
57.Fn strcpy
58function
59copies the string
60.Fa src
61to
62.Fa dst
63(including the terminating
64.Ql \e0
65character).
66.Pp
67The
68.Fn strncpy
69function copies not more than
70.Fa len
71characters from
72.Fa src
73into
74.Fa dst ,
75appending
76.Ql \e0
77characters if
78.Fa src
79is less than
80.Fa len
81characters long, and
82.Em not
83terminating
84.Fa dst
85otherwise.
86.Sh RETURN VALUES
87The
88.Fn strcpy
89and
90.Fn strncpy
91functions
92return
93.Fa dst .
94.Sh EXAMPLES
95The following sets
96.Va chararray
97to
98.Dq Li abc\e0\e0\e0 :
99.Bd -literal -offset indent
100char chararray[6];
101
102(void)strncpy(chararray, "abc", sizeof(chararray));
103.Ed
104.Pp
105The following sets
106.Va chararray
107to
108.Dq Li abcdef :
109.Bd -literal -offset indent
110char chararray[6];
111
112(void)strncpy(chararray, "abcdefgh", sizeof(chararray));
113.Ed
114.Pp
115Note that it does
116.Em not
117.Tn NUL
118terminate
119.Va chararray
120because the length of the source string is greater than or equal
121to the length parameter.
122.Pp
123The following copies as many characters from
124.Va input
125to
126.Va buf
127as will fit and
128.Tn NUL
129terminates the result.
130Because
131.Fn strncpy
132does
133.Em not
134guarantee to
135.Tn NUL
136terminate the string itself, this must be done explicitly.
137.Bd -literal -offset indent
138char buf[1024];
139
140(void)strncpy(buf, input, sizeof(buf) - 1);
141buf[sizeof(buf) - 1] = '\e0';
142.Ed
143.Pp
144This could be better achieved using
145.Xr strlcpy 3 ,
146as shown in the following example:
147.Pp
148.Dl "(void)strlcpy(buf, input, sizeof(buf));"
149.Pp
150Note that because
151.Xr strlcpy 3
152is not defined in any standards, it should
153only be used when portability is not a concern.
154.Sh SEE ALSO
155.Xr bcopy 3 ,
156.Xr memccpy 3 ,
157.Xr memcpy 3 ,
158.Xr memmove 3 ,
159.Xr strlcpy 3
160.Sh STANDARDS
161The
162.Fn strcpy
163and
164.Fn strncpy
165functions
166conform to
167.St -isoC .
168