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C++ 创建一个类的实例?

转载 作者:太空宇宙 更新时间:2023-11-04 16:25:30 24 4
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Possible Duplicate:
Default constructor with empty brackets
Instantiate class with or without parentheses?

程序:

class Foo
{
public:
Foo ( int bar = 1 )
{
cout << "bar=" << bar;
}
};

int main() {

cout << "0 - ";
Foo foo_0 ( 0 ) ;
cout << '\n';

cout << "1 - ";
Foo foo_1 ();
cout << '\n';

cout << "2 - ";
Foo foo_4;
cout << '\n';

return 0;

}

输出:

0 - bar=0
1 -
2 - bar=1

问题:为什么示例 #1 不起作用,而示例 #0 和 #2 可以?

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