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.\"     @(#)strdup.3	8.1 (Berkeley) 6/9/93
.\"
.Dd May 5, 2020
.Dt STRDUP 3
.Os
.Sh NAME
.Nm strdup ,
.Nm strndup
.Nd save a copy of a string
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft char *
.Fn strdup "const char *str"
.Ft char *
.Fn strndup "const char *str" "size_t len"
.Sh DESCRIPTION
The
.Fn strdup
function
allocates sufficient memory for a copy
of the string
.Fa str ,
does the copy, and returns a pointer to it.
The memory is allocated with
.Xr malloc 3
and should be released with
.Xr free 3
when no longer needed.
.Pp
The
.Fn strndup
function copies at most
.Fa len
characters from the string
.Fa str
always
.Dv NUL
terminating the copied string.
.Sh RETURN VALUES
If insufficient memory is available, NULL is returned and
.Va errno
is set to
.Er ENOMEM .
Otherwise, the
.Fn strdup
family of functions return a pointer to the copied string.
.Sh SEE ALSO
.Xr free 3 ,
.Xr malloc 3 ,
.Xr wcsdup 3
.Sh STANDARDS
The
.Fn strdup
function is specified by
.St -p1003.1-2001 .
The
.Fn strndup
function is specified by
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn strdup
function first appeared in
.Bx 4.3 Reno .
The
.Fn strndup
function was added in
.Fx 7.2 .