STRCAT(3)						     Linux Programmer's Manual							 STRCAT(3)

NAME

       strcat, strncat - concatenate two strings

SYNOPSIS

       #include <string.h>

       char *strcat(char *dest, const char *src);

       char *strncat(char *dest, const char *src, size_t n);

DESCRIPTION

       The  strcat() function appends the src string to the dest string, overwriting the terminating null byte ('') 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 bytes.

       As with strcat(), the resulting string in dest is always null-terminated.

       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:

	   char*
	   strncat(char *dest, const char *src, size_t n)
	   {
	       size_t dest_len = strlen(dest);
	       size_t i;

	       for (i = 0 ; i < n && src[i] != '' ; i++)
		   dest[dest_len + i] = src[i];
	       dest[dest_len + i] = '';

	       return dest;
	   }

RETURN VALUE

       The strcat() and strncat() functions return a pointer to the resulting string dest.

CONFORMING TO

       SVr4, 4.3BSD, C89, C99.

NOTES

       Some systems (the BSDs, Solaris, and others) provide the following function:

	   size_t strlcat(char *dest, const char *src, size_t size);

       This function appends the null-terminated string src to the string dest, copying at most size-strlen(dest)-1 from src, and adds a null ter-
       minator	to  the result, unless size is less than strlen(dest).	This function fixes the buffer overrun problem of strcat(), but the caller
       must still handle the possibility of data loss if size is too small.  The function returns the length of the string strlcat() tried to cre-
       ate;  if  the  return  value  is greater than or equal to size, data loss occurred.  If data loss matters, the caller must either check the
       arguments 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.

SEE ALSO

       bcopy(3), memccpy(3), memcpy(3), strcpy(3), string(3), strncpy(3), wcscat(3), wcsncat(3)

COLOPHON

       This  page is part of release 3.53 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)