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/* substring.c: copy a chunk from a string.
Copyright (C) 1992, 2011 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "config.h"
/* Return a fresh copy of SOURCE[START..LIMIT], or NULL if LIMIT<START.
If LIMIT>strlen(START), it is reassigned. */
string
substring (string source, const unsigned start, const unsigned limit)
{
string result;
unsigned this_char;
unsigned length = strlen (source);
unsigned lim = limit;
/* Upper bound out of range? */
if (lim >= length)
lim = length - 1;
/* Null substring? */
if (start > limit)
return "";
/* The `2' here is one for the null and one for limit - start inclusive. */
result = xmalloc (limit - start + 2);
for (this_char = start; this_char <= limit; this_char++)
result[this_char - start] = source[this_char];
result[this_char - start] = 0;
return result;
}
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