想要优化这个程序，有什么建议吗？ [英] Want to optimize this procedure, any advice?
问题描述
我还在学习C所以我写了一个简单的应用程序，它可以让你创建一个
联系人列表（存储为结构的链接列表），将其写入文件，并且
读回来。它工作正常，但我注意到在我的加载过程中有一两个点或两个点我将malloc一个我不需要的结构，并且
处置它;我想知道是否有某种方法可以优化这个
kludge的存在：
void loadContacts（）{int fd，bytesread; if（（fd = open（" contacts.data"，O_RDONLY，0））！= -1）{struct contact * prev，* curr =（struct contact *）malloc（sizeof（struct contact））; if（curr）{if（（bytesread = read（fd，curr，sizeof（struct contact）））== sizeof（struct contact））{first.next = curr; //首先是一个全局变量，它是链表中的第一个结构} else {free（curr）; //我可以避免这样做吗？ } do {prev = curr; curr =（struct contact *）malloc（sizeof（struct contact））; prev-> next = curr; while（（bytesread = read（fd，curr，sizeof（struct contact）））== sizeof（struct contact））; if（bytesread< sizeof（struct contact））{prev-> next = NULL;自由（CURR）; //同样，这个？ } else {perror（" malloc. \ n"）;出口（1）; } close（fd）; } $
-
http：//www.metawire。组织 - 开放主机
今天获得免费外壳和
加入一个不断增长的用户社区！
I''m still learning C so I''ve written a simple app which lets you make a
contact list (stored as a linked list of structs), write it to a file, and
read it back. It works fine, but I notice in my loading procedure there''s
a point or two where I''ll malloc a struct which I then don''t need, and
dispose of it; I was wondering if there was some way I could optimize this
kludge out of existence:
void loadContacts () { int fd, bytesread; if ( (fd = open("contacts.data", O_RDONLY, 0) ) != -1 ) { struct contact *prev, *curr = (struct contact *)malloc(sizeof(struct contact)); if ( curr ) { if ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) ) { first.next = curr; // First is a global variable which is the first struct in the linked list } else { free (curr); // Can I avoid having to do this? } do { prev = curr; curr = (struct contact *)malloc(sizeof(struct contact)); prev->next = curr; } while ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) ); if ( bytesread < sizeof(struct contact) ) { prev->next = NULL; free(curr); // Likewise, this? } } else { perror("malloc.\n"); exit(1); } close (fd); }}
--
http://www.metawire.org - Open Hosting
Get your free shell today and
join a growing community of users!
推荐答案
" Michael B." <我们***** @ spamblocked.com>写道：
"Michael B." <us*****@spamblocked.com> writes:
void loadContacts（）{int fd，bytesread; if（（fd = open（" contacts.data"，O_RDONLY，0））！= -1）{struct contact * prev，* curr =（struct contact *）malloc（sizeof（struct contact））; if（curr）{if（（bytesread = read（fd，curr，sizeof（struct contact）））== sizeof（struct contact））{first.next = curr; //首先是一个全局变量，它是链表中的第一个结构} else {free（curr）; //我可以避免这样做吗？ } do {prev = curr; curr =（struct contact *）malloc（sizeof（struct contact））; prev-> next = curr; while（（bytesread = read（fd，curr，sizeof（struct contact）））== sizeof（struct contact））; if（bytesread< sizeof（struct contact））{prev-> next = NULL;自由（CURR）; //同样，这个？ } else {perror（" malloc. \ n"）;出口（1）; } close（fd）; }}
void loadContacts () { int fd, bytesread; if ( (fd = open("contacts.data", O_RDONLY, 0) ) != -1 ) { struct contact *prev, *curr = (struct contact *)malloc(sizeof(struct contact)); if ( curr ) { if ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) ) { first.next = curr; // First is a global variable which is the first struct in the linked list } else { free (curr); // Can I avoid having to do this? } do { prev = curr; curr = (struct contact *)malloc(sizeof(struct contact)); prev->next = curr; } while ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) ); if ( bytesread < sizeof(struct contact) ) { prev->next = NULL; free(curr); // Likewise, this? } } else { perror("malloc.\n"); exit(1); } close (fd); }}
我建议您在担心优惠之前学会使用换行符
。
-
当我不得不依靠不足时，我更喜欢它是我自己的。
- 理查德希思菲尔德
I recommend that you learn to use line breaks before worrying
about optimization.
--
"When I have to rely on inadequacy, I prefer it to be my own."
--Richard Heathfield
On Thu，2003年11月13日15:02:50 -0800，Ben Pfaff写道：
On Thu, 13 Nov 2003 15:02:50 -0800, Ben Pfaff wrote:
我建议您在担心之前学会使用换行符
关于优化。
I recommend that you learn to use line breaks before worrying
about optimization.
哦，我的。它在Pan中看起来格式正确，我曾经发布它。
我不太确定什么是错的，但它绝对不应该全部
在一条线上！
-
http ：//www.metawire.org - 开放主机
立即获取免费外壳和
加入不断增长的用户社区！ />
Oh my. It looks properly formatted in Pan which I used to post it.
I''m not quite sure what''s wrong but it definitely shouldn''t have been all
on one line!
--
http://www.metawire.org - Open Hosting
Get your free shell today and
join a growing community of users!
这是尝试使用GNU重新发布。如果这不起作用，我将会知道会发生什么。
void loadContacts（）{
int fd，bytesread;
if（（fd = open（" contacts.data"，O_RDONLY，0））！= -1）{
struct contact * prev，* curr =（struct contact *）malloc（sizeof（struct contact））;
if（curr）{
if（（bytesread = read（fd，curr，sizeof（struct contact）））== sizeof（struct contact））{
first.next = curr; //首先是一个全局结构，它是链表中的第一个条目
}否则{
free（curr）; //有没有办法取消这个？
}
做{
prev = curr;
curr =（struct contact *）malloc（sizeof（struct contact））;
prev-> next = curr;
} while（（bytesread = read（fd） ，curr，sizeof（struct contact）））== sizeof（struct contact））;
if（bytesread< sizeof（struct contact））{
prev-> ; next = NULL;
free（curr）; //同样，这个？
}
}其他{
perror（" malloc.\ n）;;
退出（1）;
}
关闭（fd）;
}
}
Here''s an attempt to repost using GNUs. If this doesn''t work, I
don''t know what will.
void loadContacts () {
int fd, bytesread;
if ( (fd = open("contacts.data", O_RDONLY, 0) ) != -1 ) {
struct contact *prev, *curr = (struct contact *)malloc(sizeof(struct contact));
if ( curr ) {
if ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) ) {
first.next = curr; // First is a global struct which is the first entry in the linked list
} else {
free (curr); // Is there a way to do away with this?
}
do {
prev = curr;
curr = (struct contact *)malloc(sizeof(struct contact));
prev->next = curr;
} while ( ( bytesread = read(fd, curr, sizeof(struct contact))) == sizeof(struct contact) );
if ( bytesread < sizeof(struct contact) ) {
prev->next = NULL;
free(curr); // Likewise, this?
}
} else {
perror("malloc.\n");
exit(1);
}
close (fd);
}
}
这篇关于想要优化这个程序，有什么建议吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
