char *strcat(char *dest, const char *src);
char *strncat(char *dest, const char *src, size_t n);
The strcat() function appends the src string to the dest string, over-
writing the terminating null byte ('\0') at the end of dest, and then
adds a terminating null byte. The strings may not overlap, and the
dest string must have enough space for the result. If dest is not
large enough, program behavior is unpredictable; buffer overruns are a
favorite avenue for attacking secure programs.
The strncat() function is similar, except that
* it will use at most n bytes from src; and
* src does not need to be null-terminated if it contains n or more
As with strcat(), the resulting string in dest is always null-termi-
If src contains n or more bytes, strncat() writes n+1 bytes to dest (n
from src plus the terminating null byte). Therefore, the size of dest
must be at least strlen(dest)+n+1.
A simple implementation of strncat() might be:
strncat(char *dest, const char *src, size_t n)
size_t dest_len = strlen(dest);
for (i = 0 ; i < n && src[i] != '\0' ; i++)
dest[dest_len + i] = src[i];
dest[dest_len + i] = '\0';
The strcat() and strncat() functions return a pointer to the resulting
SVr4, 4.3BSD, C89, C99.
Some systems (the BSDs, Solaris, and others) provide the following
ments before the call, or test the function return value. strlcat() is
not present in glibc and is not standardized by POSIX, but is available
on Linux via the libbsd library.
bcopy(3), memccpy(3), memcpy(3), strcpy(3), string(3), strncpy(3),
This page is part of release 3.54 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2012-07-19 STRCAT(3)
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