关于语法：在函数调用中添加“::”在C ++中做什么？

What does prepending “::” to a function call do in C++?

本问题已经有最佳答案，请猛点这里访问。

Possible Duplicate:
What is the meaning of prepended double colon “::” to class name?

我一直在看一个遗留的C++代码，它有这样的事情：

1 2	::putenv(local_tz_char); ::tzset();

在函数调用前加"：："的语法是什么意思？谷歌福让我失望了。

这意味着编译器将在全局命名空间中查找函数putenv()和tzset()。

例子

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#include <iostream>

using namespace std;

//global function
void foo()
{
cout <<"This function will be called by bar()";
}

namespace lorem
{
void foo()
{
cout <<"This function will not be called by bar()";
}

void bar()
{
::foo();
}
}

int main()
{
lorem::bar(); //will print"This function will be called by bar()"
return 0;
}

也称为范围解析运算符

In C++ is used to define the already declared member functions (in the
header file with the .hpp or the .h extension) of a particular class.
In the .cpp file one can define the usual global functions or the
member functions of the class. To differentiate between the normal
functions and the member functions of the class, one needs to use the
scope resolution operator (::) in between the class name and the
member function name i.e. ship::foo() where ship is a class and foo()
is a member function of the class ship.

维基百科的例子：

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#include <iostream>

// Without this using statement cout below would need to be std::cout
using namespace std;

int n = 12; // A global variable

int main() {
int n = 13; // A local variable
cout << ::n << endl; // Print the global variable: 12
cout << n << endl; // Print the local variable: 13
}

昨天(+1年)有一个关于类似问题的讨论。也许你可以在这里找到一个更深入的答案。

预填的双冒号"："的意思是什么？