指针方法?? [英] Pointers in methods??
问题描述
是否只允许指针指向某个方法中的某个东西？
#include< stdio.h>
struct data {
int x;
int y;
};
struct data test，* pp;
pp =& test; //为什么这是非法的？
main（）{
pp =& test;
}
为什么上面的代码是非法的？
JS写道：是否只允许使指针指向某个方法中的某个东西??
< stdio.h>
结构数据{
int x;
int y;
};
结构数据测试，* pp;
pp =& test; //为什么这是非法的？
您不能将运行时代码（赋值）放在功能块之外。
不要将赋值（运行时）与初始化混淆（编译 - 时间），
例如
struct data * pp =& test;
main（）{
pp =& test;
这个，我相信，有效。
}
在文章< ; d1 ********** @ news.net.uni-c.dk> ;, JS< dsa。@ asdf.com>写道：
：是否只允许指针指向方法中的某些内容？
C没有方法;从你的代码我怀疑你的意思
" functions" ;.
：struct data {int x; int y; };
：struct data test，* pp;
：pp =& test; //为什么这是非法的？
因为你把它放在另一条线上，所以pp
的设置不是初始化器而是声明。
尝试
struct data {int x; int y; };
结构数据测试，* pp =&测试;
-
如果你喜欢VT-52，那就太开心了's。
JS写道：是否只允许制作指针指向某个方法中的某些东西??
结构数据{
int x;
int y;
};
结构数据测试，* pp;
pp =& test; //为什么这是非法的？
因为它是一个可执行语句，并且一个可执行的
语句必须驻留在一个函数内（不是方法。
这个赋值是非法的，因为退出（）
调用或者'for''循环在这一点上是非法的。
但是，您仍然可以通过在'pp''声明中使用
初始化程序来实现目标：
struct data test，* pp =& test;
或者更清楚
struct data test;
struct data * pp =& test;
尽管存在'=''，但这不是*赋值
语句;它是一个带初始化器的声明。保持在
介意C倾向于为多个
目的重复使用相同的字符。根据上下文，`*''可以是乘法
运算符或指针解引用运算符或'/ *''
或'* /''注释的一部分标记或'* =''乘法和赋值
运算符的一部分。就这样，`=''可以是赋值运算符，或者部分
的初始化语法，或者`==''或`！=''或
$的一部分b $ b` * =''或者......尽管它们都使用`=''并且
两侧都有相同的符号集，你的代码和我的代码是/>
是不同的：一个是可执行语句，另一个是
是带有初始化程序的变量声明。
-
Er*********@sun.com
Is it only allowed to make a pointer point to something in a method??
#include <stdio.h>
struct data {
int x;
int y;
};
struct data test, *pp;
pp = &test; //WHY IS THIS ILLEGAL??
main(){
pp = &test;
}
Why is the above code illegal??
JS wrote:Is it only allowed to make a pointer point to something in a method??
#include <stdio.h>
struct data {
int x;
int y;
};
struct data test, *pp;
pp = &test; //WHY IS THIS ILLEGAL??
You cannot put run-time code (assignment) outside of a function block.
Do not confuse assignment (run-time) with initialization (compile-time),
e.g.
struct data *pp = &test;
main(){
pp = &test;
This, I trust, works.
}
In article <d1**********@news.net.uni-c.dk>, JS <dsa.@asdf.com> wrote:
:Is it only allowed to make a pointer point to something in a method??
C doesn''t have "methods"; from your code I suspect you mean
"functions".
:struct data { int x; int y; };
:struct data test, *pp;
:pp = &test; //WHY IS THIS ILLEGAL??
Because you have it on a different line, the setting of pp
is not an initializer but rather a statement.
Try
struct data { int x; int y; };
struct data test, *pp = &test;
--
Feep if you love VT-52''s.
JS wrote:Is it only allowed to make a pointer point to something in a method??
#include <stdio.h>
struct data {
int x;
int y;
};
struct data test, *pp;
pp = &test; //WHY IS THIS ILLEGAL??
Because it is an executable statement, and an executable
statement must reside inside a function (not "method").
This assignment is illegal for the same reason an exit()
call or a `for'' loop would be illegal at this point.
However, you can still achieve your goal by using an
initializer in the declaration of `pp'':
struct data test, *pp = &test;
or perhaps more clearly
struct data test;
struct data *pp = &test;
Despite the presence of the `='' this is *not* an assignment
statement; it is a declaration with an initializer. Keep in
mind that C tends to re-use the same character for multiple
purposes. Depending on context, `*'' can be the multiplication
operator or the pointer dereference operator or part of a `/*''
or `*/'' comment marker or part of the `*='' multiply-and-assign
operator. Just so, `='' can be the assignment operator, or part
of the syntax of an initialization, or part of `=='' or `!='' or
`*='' or ... Despite the fact that they both use `='' and have
the same set of symbols on both sides of it, your code and mine
are different: one is an executable statement, and the other
is a variable declaration with an initializer.
--
Er*********@sun.com
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