Formatted strncat(3):
strncat(3) Library Functions Manual strncat(3)
NAME
strncat - concatenate a null‐padded character sequence into a string
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <string.h>
char *strncat(char *restrict dst, const char src[restrict .sz],
size_t sz);
DESCRIPTION
This function catenates the input character sequence contained in a
null‐padded fixed‐width buffer, into a string at the buffer pointed to
by dst. The programmer is responsible for allocating a buffer large
enough, that is, strlen(dst) + strnlen(src, sz) + 1.
An implementation of this function might be:
char *
strncat(char *restrict dst, const char *restrict src, size_t sz)
{
int len;
char *end;
len = strnlen(src, sz);
end = dst + strlen(dst);
end = mempcpy(end, src, len);
*end = '\0';
return dst;
}
RETURN VALUE
strncat() returns dest.
ATTRIBUTES
For an explanation of the terms used in this section, see attrib‐
utes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│strncat() │ Thread safety │ MT‐Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
POSIX.1‐2001, POSIX.1‐2008, C89, C99, SVr4, 4.3BSD.
CAVEATS
The name of this function is confusing. This function has no relation
to strncpy(3).
If the destination buffer is not large enough, the behavior is unde‐
fined. See _FORTIFY_SOURCE in feature_test_macros(7).
BUGS
This function can be very inefficient. Read about Shlemiel the painter
⟨https://www.joelonsoftware.com/2001/12/11/back-to-basics/⟩;.
EXAMPLES
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(void)
{
char buf[BUFSIZ];
size_t len;
buf[0] = '\0'; // There’s no ’cpy’ function to this ’cat’.
strncat(buf, "Hello XXX", 6);
strncat(buf, "world", 42);
strncat(buf, "!", 1);
len = strlen(buf);
printf("[len = %zu]: ", len);
puts(buf); // "Hello world!"
exit(EXIT_SUCCESS);
}
SEE ALSO
string(3), string_copy(3)
Linux man‐pages (unreleased) (date) strncat(3)
--
<http://www.alejandro-colomar.es/>
Attachment:
OpenPGP_signature
Description: OpenPGP digital signature
