为什么C ++名称为Mangle标识符？ [英] Why Does C++ Name-Mangle Identifiers?
问题描述
为什么这有必要？由
程序员提供的标识符是唯一的，这就是重要的 - 为什么
将用户指定的内容映射到其他内容？
-
Randy Yates
索尼爱立信移动通信
美国北卡罗来纳州三角研究园
ra ********* @ sonyericsson.com ，919-472-1124
Randy Yates写道：为什么这有必要？由程序员提供的标识符是唯一的，这是重要的 - 为什么
将用户指定的内容映射到其他内容？
void X（）;
void X（int）;
哪个链接符号应为X？
" Randy Yates" < RA ********* @ sonyericsson.com>在消息中写道
news：xx ************* @usrts005.corpusers.net ...为什么这有必要？由程序员提供的标识符是唯一的，这是重要的 - 为什么
将用户指定的内容映射到其他内容？
但他们不是。
int my_overloaded_function（int x）
{
返回x;
}
int my_overloaded_function（int x，int y）
{
返回x + y;
}
在C ++中定义两个具有相同名称的不同函数是合法的。
通常C ++实现会破坏名称因此非C ++感知链接器可以区分这些函数。
john
Randy Yates写道：
为什么这有必要？由程序员提供的标识符是唯一的，这是重要的 - 为什么
将用户指定的内容映射到其他内容？
因为大多数C ++编译器是围绕依赖于系统的
链接器构建的。那些链接器有一个简单的规则：如果2个函数具有相同名称的
，那么它们是相同的函数。在大多数（如果不是全部）编程语言中，
是真的，这需要链接。
但是在C ++中它是完美的如果只有他们的参数类型不同，则有两个不同的函数
具有相同的名称。
这就是为什么引入名称错误的原因：To将信息添加到
函数的名称，为函数创建不同的名称
，名称相同但参数类型不同。
另一种方法是编写一个新的目标文件
格式和一个可以处理它的新链接器。只要你只有C ++这个就没有大问题了。但正如所说：在大多数大机器（例如大型机）上，只有一个对象
文件格式定义，只有一个系统范围的链接器可以链接
一个应用程序。这是一件好事，因为这意味着你可以自由地链接用不同编程语言编写的模块。
但它也意味着：你必须为<引入一些机制
编译器使函数名称唯一，即使它们在源代码中具有相同的
名称。
-
Karl Heinz Buchegger
kb******@gascad.at
Why is this necessary? The identifiers provide by the
programmer are unique, and that is what is important - why
map what the user has specified to something else?
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
ra*********@sonyericsson.com, 919-472-1124
Randy Yates wrote:Why is this necessary? The identifiers provide by the
programmer are unique, and that is what is important - why
map what the user has specified to something else?
void X();
void X( int );
Which linker symbol should be X ?
"Randy Yates" <ra*********@sonyericsson.com> wrote in message
news:xx*************@usrts005.corpusers.net...Why is this necessary? The identifiers provide by the
programmer are unique, and that is what is important - why
map what the user has specified to something else?
But they aren''t.
int my_overloaded_function(int x)
{
return x;
}
int my_overloaded_function(int x, int y)
{
return x + y;
}
In C++ it''s legal to define two different functions with the same name.
Typically C++ implementations mangle the names so non-C++ aware linkers can
distinguish the functions.
john
Randy Yates wrote:
Why is this necessary? The identifiers provide by the
programmer are unique, and that is what is important - why
map what the user has specified to something else?
Because most C++ compilers are built around a system dependent
linker. Those linker have a simple rule: if 2 functions have
the same name, then they are the same function. This was
true in most (if not all) programming languages which
required linking.
But in C++ it is perfectly valid to have 2 different functions
with the same name, if only their argument types are different.
That''s why name mangling was introduced: To add information to
the name of a function to create different names for functions
with the same name but different argument types.
The alternative would have been to write new a new object file
format and a new linker that can deal with that. As long as you
only have C++ this would be no big problem. But as said: on most
''big machines'' (such as mainframes), there is only one object
file format defined and only one system wide linker to link
an application. That''s a good thing, because it means you can
freely link modules written in different programming languages.
But it also means: You have to introduce some mechanism for
the compiler to make function names unique even if they have identical
names in the source code.
--
Karl Heinz Buchegger
kb******@gascad.at
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