简单的指针问题 [英] simple pointer question
问题描述
在下面的代码中，有人能告诉我* p ++和
p ++之间的区别吗？我可以看到两者都达到了相同的结果。
非常感谢！
#include< iostream>
using namespace :: std;
int main（）{
char * p =" test pointer";
而（* p）{
cout<< * p;
* p ++; //<< - * p ++和p ++之间有什么区别（两个实现
相同的结果）？
}
cout << endl;
返回0;
}
" lokman" <螺**** @ fagi.net>在消息中写道
news：c5 ********** @nn-tk102.ocn.ad.jp ...
*的p ++; //<< - * p ++和p ++之间有什么区别（两者都实现了相同的结果）？
p ++递增指针，就像你期望的那样* p ++首先取消引用
指针，然后递增它。由于解除引用的临时不是分配给任何东西的b $ b，它会被丢弃。
hth
-
jb
（如果你想通过电子邮件回复，用x代替y）
周六，17 2004年4月23:10:00 +0900，lokman <螺**** @ fagi.net>写道：
在下面的代码中，有人可以告诉我* p ++和
p ++？我可以看到两者都达到了相同的结果。
非常感谢！
#include< iostream>
使用namespace :: std;
int main（）{
char * p =" test pointer" ;;
while（* p）{
cout<< * p;
* p ++; //<< - * p ++和p ++之间有什么区别（两者都有相同的结果）？
}
cout<< endl;
返回0;
}
在这种情况下没有差异。
如果你要做一个cout<< * p ++
然后它会打印p'的当前字符然后
incr ptr
* p得到值来自ptr
++ incr ptr的类型大小。
/ ak
" lokman" <螺**** @ fagi.net>在消息中写道
news：c5 ********** @nn-tk102.ocn.ad.jp ...
在下面的代码中，有人能告诉我* p ++和
p ++之间的区别吗？我可以看到两者都达到了相同的结果。
非常感谢！
好的，
p ++增加了指针
* p获取指针所指向的变量的内容
你可以写在你的循环中
cout<< * p ++<< endl;
由于*运算符的优先级，所以* p在p ++之前完成，
也许你会更清楚写一下（* p）++（不要在编码中使用这个... / b $ b这只是为了让你理解你应该在代码中编写* p ++）
也许复制两个字符串的例子;
char * s1 =" test";
char * s2 =" blab";
for（unsigned int i = 0; i< strlen（s1）; i ++）
* s1 ++ = * s2 ++;
因此s1的内容成为s2的内容;
注意它们都是相同的大小，如果不是你可能有
未定义的行为。
但如果哟你想复制strign我会建议使用< string>
而不是char *。
HTH
- < br $>
Frane Roje
祝你有愉快的一天
从电子邮件中删除（* dele * te）以回复
Hi,
In the following code, can someone tell me the difference between *p++ and
p++ ? I can see both achieve the same result.
Thanks a lot !
#include <iostream>
using namespace::std;
int main() {
char *p = "test pointer";
while (*p) {
cout << *p;
*p++; // <<- What is the difference between *p++ and p++ (both achieve
the same result) ?
}
cout << endl;
return 0;
}
"lokman" <lo****@fagi.net> wrote in message
news:c5**********@nn-tk102.ocn.ad.jp...
*p++; // <<- What is the difference between *p++ and p++ (both achieve
the same result) ?
p ++ increments the pointer, like you expect. *p ++ first dereferences
the pointer, and then increments it. Since the dereferenced temporary is not
assigned to anything, it is discarded.
hth
--
jb
(replace y with x if you want to reply by e-mail)
On Sat, 17 Apr 2004 23:10:00 +0900, "lokman" <lo****@fagi.net> wrote:
Hi,
In the following code, can someone tell me the difference between *p++ and
p++ ? I can see both achieve the same result.
Thanks a lot !
#include <iostream>
using namespace::std;
int main() {
char *p = "test pointer";
while (*p) {
cout << *p;
*p++; // <<- What is the difference between *p++ and p++ (both achieve
the same result) ?
}
cout << endl;
return 0;
}
in this context there is no diff.
if you would for instance do a cout << *p++
then it would print p''s current char and then
incr the ptr
*p get the value from the ptr
++ incr the ptr with whatever size of type it is.
/ak
"lokman" <lo****@fagi.net> wrote in message
news:c5**********@nn-tk102.ocn.ad.jp...Hi,
In the following code, can someone tell me the difference between *p++ and
p++ ? I can see both achieve the same result.
Thanks a lot !
Ok,
p++ increments the pointer
*p gets the contents of the variable to which the pointer is pointing to
You could write in your loop
cout<<*p++<<endl;
Because of the precedence of the * operator so the *p is done before p++,
maybe it would be more clear if you wrote (*p)++ (don''t use this in coding
this is just for you to understand you should write *p++ in your code)
Maybe an example of copying two strings;
char *s1="test";
char *s2="blab";
for(unsigned int i=0;i<strlen(s1);i++)
*s1++=*s2++;
So the content of the s1 becomes the content of the s2;
Note that they are both the same size, if not you might have
undefined behavior.
But if you want to copy strign I would reccomed using <string>
rather than char*.
HTH
--
Frane Roje
Have a nice day
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