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
       ('\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 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] != '\0' ; i++)
                   dest[dest_len + i] = src[i];
               dest[dest_len + i] = '\0';

               return dest;
           }

RETURN VALUE

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

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────┬───────────────┬─────────┐
       │ Interface           │ Attribute     │ Value   │
       ├─────────────────────┼───────────────┼─────────┤
       │ strcat(), strncat() │ Thread safety │ MT-Safe │
       └─────────────────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

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 terminating null byte 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 create; 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

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       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       http://www.kernel.org/doc/man-pages/.

GNU                                                2015-08-08                                          STRCAT(3)