glibc中函数的定义
0
悬赏园豆：15
[已解决问题]
解决于 2013-10-21 13:19
char *
strcat (dest, src)
char *dest;
const char *src;
{
char *s1 = dest;
const char *s2 = src;
char c;
/* Find the end of the string. */
do
c = *s1++;
while (c != '\0');
/* Make S1 point before the next character, so we can increment
it while memory is read (wins on pipelined cpus). */
s1 -= 2;
do
{
c = *s2++;
*++s1 = c;
}
while (c != '\0');
return dest;
}
请问红色部分为什么要那么写，这个glibc中完整函数定义
问题补充：
/* Copyright (C) 1991-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <string.h>
#include <memcopy.h>
#undef strcat
/* Append SRC on the end of DEST. */
char *
strcat (dest, src)
char *dest;
const char *src;
{
char *s1 = dest;
const char *s2 = src;
char c;
/* Find the end of the string. */
do
c = *s1++;
while (c != '\0');
/* Make S1 point before the next character, so we can increment
it while memory is read (wins on pipelined cpus). */
s1 -= 2;
do
{
c = *s2++;
*++s1 = c;
}
while (c != '\0');
return dest;
}
libc_hidden_builtin_def (strcat)
最佳答案
0
那是很久以前c语言还没标准化的时候参数的写法。
收获园豆：10
其他回答(2)
0
能否贴完整点，红色部分语法都有错误。
0
旧的语法而已。
收获园豆：5