Both Integer and function in C++

Question

class Foo
{
public:
  // single parameter constructor, can be used as an implicit conversion
  Foo (int foo) : m_foo (foo) 
  {
  }

  int GetFoo () { return m_foo; }

private:
  int m_foo;
};

m_foo is an integer as defined in private section, but what's m_foo(foo)? that looks like a function.

is m_foo both an integer and a function? How does that work?

And Foo(int foo) contructor is extending the m_foo function.

http://www.cprogramming.com/tutorial/initialization-lists-c++.html — Timothy Shields, Aug 26 '13 at 15:41
http://stackoverflow.com/questions/1598967/benefits-of-initialization-lists — Bill Lynch, Aug 26 '13 at 15:43
It's like doing `int x(42);` in a local context, but instead doing it in an initialization list. — Cornstalks, Aug 26 '13 at 15:44
http://stackoverflow.com/questions/926752/why-should-i-prefer-to-use-member-initialization-list — Adam Burry, Aug 26 '13 at 15:44

score 5 · Answer 1 · answered Aug 26 '13 at 15:42

5

Foo (int foo) : m_foo (foo)

This is an initializer list. It initialises m_foo to have the value foo.

answered Aug 26 '13 at 15:42

David Heffernan

601,492
42
1,072
1,490

score 2 · Answer 2 · answered Aug 26 '13 at 15:43

2

You are initializing a integer variable using initializer list. Essentially before you enter the body of the constructor m_foo is assinged to foo.

answered Aug 26 '13 at 15:43

Ivaylo Strandjev

69,226
18
123
176

score 1 · Answer 3 · answered Aug 26 '13 at 15:43

1

It is an intializer. It sets the value of the m_foo item by calling it's copy-constructor (instead of creating a temporary object and then calling the copy-constructor if you were to set it in the constructor like m_foo = foo).

answered Aug 26 '13 at 15:43

Zac Howland

15,777
1
26
42

score -1 · Answer 4 · answered Aug 26 '13 at 15:42

-1

^{I'm not sure that basic questions about C++ have their place here, however:}

Foo (int foo) : m_foo (foo)

means: define a constructor, and initialize the member variable m_foo with the foo formal argument.

answered Aug 26 '13 at 15:42

Basile Starynkevitch

223,805
18
296
547

Both Integer and function in C++

4 Answers4