strncat.c

一组基础的C库的实现

/* $Id: strncat.c 262 2006-11-16 07:34:57Z solar $ */

/* Release $Name$ */

/* strncat( char *, const char *, size_t )

   This file is part of the Public Domain C Library (PDCLib).
   Permission is granted to use, modify, and / or redistribute at will.
*/

#include <string.h>

#ifndef REGTEST

char * strncat( char * _PDCLIB_restrict s1, const char * _PDCLIB_restrict s2, size_t n )
{
    char * rc = s1;
    while ( *s1 )
    {
        ++s1;
    }
    while ( n && ( *s1++ = *s2++ ) )
    {
        --n;
    }
    if ( n == 0 )
    {
        *s1 = '\0';
    }
    return rc;
}

#endif

#ifdef TEST
#include <_PDCLIB_test.h>

int main()
{
    char s[] = "xx\0xxxxxx";
    BEGIN_TESTS;
    TESTCASE( strncat( s, abcde, 10 ) == s );
    TESTCASE( s[2] == 'a' );
    TESTCASE( s[6] == 'e' );
    TESTCASE( s[7] == '\0' );
    TESTCASE( s[8] == 'x' );
    s[0] = '\0';
    TESTCASE( strncat( s, abcdx, 10 ) == s );
    TESTCASE( s[4] == 'x' );
    TESTCASE( s[5] == '\0' );
    TESTCASE( strncat( s, "\0", 10 ) == s );
    TESTCASE( s[5] == '\0' );
    TESTCASE( s[6] == 'e' );
    TESTCASE( strncat( s, abcde, 0 ) == s );
    TESTCASE( s[5] == '\0' );
    TESTCASE( s[6] == 'e' );
    TESTCASE( strncat( s, abcde, 3 ) == s );
    TESTCASE( s[5] == 'a' );
    TESTCASE( s[7] == 'c' );
    TESTCASE( s[8] == '\0' );
    return TEST_RESULTS;
}
#endif