NAME
strncat —
concatenate a string with part of
another
SYNOPSIS
#include
<string.h>
char *
strncat(char
*s, const char
*append, size_t
count);
DESCRIPTION
The
strncat()
function appends not more than count characters of the
NUL-terminated string append to the end of the
NUL-terminated string s. Space for the terminating
‘\0’ should not be included in
count. The string s must have
sufficient space to hold the result.
RETURN VALUES
The strncat() function returns the pointer
s.
EXAMPLES
The following appends “abc”
to chararray:
char *letters = "abcdefghi"; (void)strncat(chararray, letters, 3);
The following example shows how to use
strncat() safely in conjunction with
strncpy(3).
char buf[BUFSIZ]; char *input, *suffix; (void)strncpy(buf, input, sizeof(buf) - 1); buf[sizeof(buf) - 1] = '\0'; (void)strncat(buf, suffix, sizeof(buf) - 1 - strlen(buf));
The above will copy as many characters from input to buf as will fit. It then appends as many characters from suffix as will fit (or none if there is no space). For operations like this, the strlcpy(3) and strlcat(3) functions are a better choice, as shown below.
(void)strlcpy(buf, input, sizeof(buf)); (void)strlcat(buf, suffix, sizeof(buf));
SEE ALSO
bcopy(3), memccpy(3), memcpy(3), memmove(3), strcat(3), strcpy(3), strlcpy(3), wcscat(3), wcslcpy(3)
STANDARDS
The strcat() and
strncat() functions conform to ANSI
X3.159-1989 (“ANSI C89”).
HISTORY
The strncat() function first appeared in
Version 7 AT&T UNIX.