---
name: "stpncpy"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/stpcpy"
---

# stpncpy(3)

copy strings

Part of [stpcpy(3)](/stpcpy/3.md).

## NAME

**stpcpy**, **stpncpy**, **strcpy**, **strncpy** – copy strings

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<string.h\>**

*char* *\**\

**stpcpy**(*char \* restrict dst*, *const char \* restrict src*);

*char* *\**\

**stpncpy**(*char \* restrict dst*, *const char \* restrict src*, *size\_t len*);

*char* *\**\

**strcpy**(*char \* restrict dst*, *const char \* restrict src*);

*char* *\**\

**strncpy**(*char \* restrict dst*, *const char \* restrict src*, *size\_t len*);

## DESCRIPTION

The **strcpy**() and **stpcpy**() functions copy the string *src* to *dst* (including the terminating ‘\\0’ character.)

The **strncpy**() and **stpncpy**() functions copy at most *len* characters from *src* into *dst*. If *src* is less than *len* characters long, the remainder of *dst* is filled with ‘\\0’ characters. Otherwise, *dst* is *not* terminated.

For all of **strcpy**(), **strncpy**(), **stpcpy**(), and **stpncpy**(), the result is undefined if *src* and *dst* overlap.

## RETURN VALUES

The **strcpy**() and **strncpy**() functions return *dst*. The **stpcpy**() and **stpncpy**() functions return a pointer to the terminating ‘\\0’ character of *dst*. If **stpncpy**() does not terminate *dst* with a NUL character, it instead returns a pointer to dst\[n\] (which does not necessarily refer to a valid memory location.)

## EXAMPLES

The following sets *chararray* to “abc\\0\\0\\0”:

```
char chararray[6];
(void)strncpy(chararray, "abc", sizeof(chararray));
```

The following sets *chararray* to “abcdef”:

```
char chararray[6];
(void)strncpy(chararray, "abcdefgh", sizeof(chararray));
```

Note that it does *not* NUL terminate *chararray* because the length of the source string is greater than or equal to the length argument.

The following copies as many characters from *input* to *buf* as will fit and NUL terminates the result. Because **strncpy**() does *not* guarantee to NUL terminate the string itself, this must be done explicitly.

```
char buf[1024];
(void)strncpy(buf, input, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = '\0';
```

This could be better achieved using [strlcpy(3)](/strlcpy/3.md), as shown in the following example:

```
(void)strlcpy(buf, input, sizeof(buf));
```

## SEE ALSO

[bcopy(3)](/bcopy/3.md), [memccpy(3)](/memccpy/3.md), [memcpy(3)](/memcpy/3.md), [memmove(3)](/memmove/3.md), [strlcpy(3)](/strlcpy/3.md), [wcscpy(3)](/wcscpy/3.md)

## STANDARDS

The **strcpy**() and **strncpy**() functions conform to ISO/IEC 9899:1990 (“ISO C90”). The **stpcpy**() and **stpncpy**() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

## HISTORY

The **stpcpy**() function first appeared in FreeBSD 4.4, and **stpncpy**() was added in FreeBSD 8.0.

## SECURITY CONSIDERATIONS

All of the functions documented in this manual page are easily misused in a manner which enables malicious users to arbitrarily change a running program's functionality through a buffer overflow attack.

It is strongly suggested that the **strlcpy**() function be used in almost all cases.

For some, but not all, fixed-length records, non-terminated strings may be both valid and desirable. In that specific case, the **strncpy**() function may be most sensible.