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strncpy (3)
  • >> strncpy (3) ( FreeBSD man: Библиотечные вызовы )
  • strncpy (3) ( Русские man: Библиотечные вызовы )
  • strncpy (3) ( Linux man: Библиотечные вызовы )
  • strncpy (3) ( POSIX man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    
    
    strcpy , strncpy
    
     - copy strings
    
     
    

    LIBRARY

    Lb libc
    
     
    

    SYNOPSIS

       #include <string.h>
    char * stpcpy (char *dst const char *src);
    char * strcpy (char * restrict dst const char * restrict src);
    char * strncpy (char * restrict dst const char * restrict src size_t len);
     

    DESCRIPTION

    The stpcpy ();
    and strcpy ();
    functions copy the string Fa src to Fa dst (including the terminating `\0' character.)

    The strncpy ();
    function copies at most Fa len characters from Fa src into Fa dst . If Fa src is less than Fa len characters long, the remainder of Fa dst is filled with `\0' characters. Otherwise, Fa dst is not terminated.  

    RETURN VALUES

    The strcpy ();
    and strncpy ();
    functions return Fa dst . The stpcpy ();
    function returns a pointer to the terminating `\0' character of Fa dst .  

    EXAMPLES

    The following sets chararray to ``abc\0\0\0 ''
    char chararray[6];
    
    (void)strncpy(chararray, "abc", sizeof(chararray));
    

    The following sets chararray to ``abcdef ''

    char chararray[6];
    
    (void)strncpy(chararray, "abcdefgh", sizeof(chararray));
    

    Note that it does not NUL terminate chararray because the length of the source string is greater than or equal to the length argument.

    The following copies as many characters from input to buf as will fit and NUL terminates the result. Because strncpy ();
    does not guarantee to NUL terminate the string itself, this must be done explicitly.

    char buf[1024];
    
    (void)strncpy(buf, input, sizeof(buf) - 1);
    buf[sizeof(buf) - 1] = '\0';
    

    This could be better achieved using strlcpy(3), as shown in the following example:

    "(void)strlcpy(buf, input, sizeof(buf));"

    Note that because strlcpy(3) is not defined in any standards, it should only be used when portability is not a concern.  

    SECURITY CONSIDERATIONS

    The strcpy ();
    function is easily misused in a manner which enables malicious users to arbitrarily change a running program's functionality through a buffer overflow attack. (See the FSA and Sx EXAMPLES . )  

    SEE ALSO

    bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3)  

    STANDARDS

    The strcpy ();
    and strncpy ();
    functions conform to St -isoC . The stpcpy ();
    function is an MS-DOS and GNUism. The stpcpy ();
    function conforms to no standard.  

    HISTORY

    The stpcpy ();
    function first appeared in Fx 4.4 , coming from 1998-vintage Linux.


     

    Index

    NAME
    LIBRARY
    SYNOPSIS
    DESCRIPTION
    RETURN VALUES
    EXAMPLES
    SECURITY CONSIDERATIONS
    SEE ALSO
    STANDARDS
    HISTORY


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