Programming Forums > Application Development > C++

BrinyCode · Nov 20th, 2005, 10:47 PM

What are these symbols in C++, I can't find an explaination for them ---> ::

tempest · Nov 20th, 2005, 10:59 PM

I can't remember what it's called, PHP's debugger calls it a "PAAMAYIM_NEKUDOTAYIM".

Basically what it's used for is defining class functions outside of the class delcaration...

Example:

(Toggle Plain Text)

class test {
	public:
		inline test();
};

inline test::test() {
	// Here's some code..
}

Jessehk · Nov 20th, 2005, 11:33 PM

the :: is the ownership operator. For example:

(Toggle Plain Text)

class Test
{
	private:
		int number;
	public:
		Test(int x)
			: number(x) {}
};

In this case, anything beginning with ...

(Toggle Plain Text)

Test::

would tell the compiler that it belonged to the Test class.

For example:

(Toggle Plain Text)

Test::number //bad example, because number is private

This can also apply to namespaces. Hope that helped

EDIT: I think more examples are in order.

(Toggle Plain Text)

class Test
{
	private:
		int number;
	public:
		Test(int);
		void mult(int);
		void print() const;
};

//using the ownership operator to define class methods
//first the constructor
Test::Test(int x)
{
	number = x;
}

//then the mult (multiply) method
void Test::mult(int x)
{
	number *= x;
}

//then maybe a display method
void Test::print() const
{
	std::cout << number << std::endl; //ownership operator used to denote namespace ownership as well
}

Feel free to pm if you still don't understand

BrinyCode · Nov 21st, 2005, 12:27 AM

Well you made a couple good points that lead for me to ask:

1. Classes ( I this as it name it implies)
2. ownership operator (Does it really mean ownership?)
3. Also why do we see "std" with it some times.

Just to let you know I am not Pro, just in video game development and relatively new to the C++ language in case I sound like a noob. That's because I am a noob when it comes to the C++ language.

andro · Nov 21st, 2005, 1:12 AM

Ermm, :: is the scope resolution operator.

coldDeath · Nov 21st, 2005, 3:06 AM

Well std is a namespace and as Jessehk mentioned, it applies to namespaces aswell.

So cout is a function to output something. It is declared in the std namespace, so you'd use this:

(Toggle Plain Text)

std::cout<<"blah";

But you don't have to use the std:: part if you declare the namespace globally using this:

(Toggle Plain Text)

using namespace std;

Arevos · Nov 21st, 2005, 4:09 AM

Quote:

Originally Posted by BrinyCode

Well you made a couple good points that lead for me to ask:
[b]
1. Classes ( I this as it name it implies)

Are you asking what classes are, or have I just misread what you've said?

Classes are the blueprints of objects. Objects are structures that contain both data and code.

You really need to understand about classes and objects if you're going to code in C++.

DaWei · Nov 21st, 2005, 7:51 AM

As Andros said, "::" is the scope (not ownership) resolution operator. With that terminology, you should be able to find what you were looking for.

BrinyCode · Nov 21st, 2005, 3:27 PM

Quick question, why the word scope and if we did not use them what would happen?

Cache · Nov 21st, 2005, 4:10 PM

Here are some definitions of the word "scope":

1. Breadth or opportunity to function.
2. The area covered by a given activity or subject.

I'm very new to programming, so if I can understand "why the word scope" from it's definition, I'm sure you can too. I think from that you can also assume what may happen if you try to use an object without bringing it into scope, from outside it's "opportunity to function", the "area covered by a given activity or subject".

Perhaps someone else will give you a more technically sound answer but I think it's good practice to look at the definition of words you use if you don't understand why you are using them.

Nov 20th, 2005, 10:47 PM	#1
BrinyCode Newbie Join Date: Nov 2005 Posts: 11 Rep Power: 0	What are these symbols ---> :: What are these symbols in C++, I can't find an explaination for them ---> ::

Nov 20th, 2005, 10:59 PM	#2
tempest Programming Guru Join Date: Oct 2004 Posts: 1,041 Rep Power: 6	I can't remember what it's called, PHP's debugger calls it a "PAAMAYIM_NEKUDOTAYIM". Basically what it's used for is defining class functions outside of the class delcaration... Example: (Toggle Plain Text) class test { public: inline test(); }; inline test::test() { // Here's some code.. } class test { public: inline test(); }; inline test::test() { // Here's some code.. } __________________

Nov 20th, 2005, 11:33 PM	#3
Jessehk The Oblivious One Join Date: May 2005 Location: Ontario, Canada Posts: 646 Rep Power: 4	the :: is the ownership operator. For example: (Toggle Plain Text) class Test { private: int number; public: Test(int x) : number(x) {} }; class Test { private: int number; public: Test(int x) : number(x) {} }; In this case, anything beginning with ... (Toggle Plain Text) Test:: Test:: would tell the compiler that it belonged to the Test class. For example: (Toggle Plain Text) Test::number //bad example, because number is private Test::number //bad example, because number is private This can also apply to namespaces. Hope that helped EDIT: I think more examples are in order. (Toggle Plain Text) class Test { private: int number; public: Test(int); void mult(int); void print() const; }; //using the ownership operator to define class methods //first the constructor Test::Test(int x) { number = x; } //then the mult (multiply) method void Test::mult(int x) { number = x; } //then maybe a display method void Test::print() const { std::cout << number << std::endl; //ownership operator used to denote namespace ownership as well } class Test { private: int number; public: Test(int); void mult(int); void print() const; }; //using the ownership operator to define class methods //first the constructor Test::Test(int x) { number = x; } //then the mult (multiply) method void Test::mult(int x) { number = x; } //then maybe a display method void Test::print() const { std::cout << number << std::endl; //ownership operator used to denote namespace ownership as well } Feel free to pm if you still don't understand __________________ Dr. Zoidberg: [ecstatic] I'm going to a movie... with FRIENDS! Last edited by Jessehk; Nov 20th, 2005 at 11:43 PM.

Nov 21st, 2005, 3:06 AM	#6
coldDeath Expert Programmer Join Date: Aug 2005 Location: UK Posts: 862 Rep Power: 4	Well std is a namespace and as Jessehk mentioned, it applies to namespaces aswell. So cout is a function to output something. It is declared in the std namespace, so you'd use this: (Toggle Plain Text) std::cout<<"blah"; std::cout<<"blah"; But you don't have to use the std:: part if you declare the namespace globally using this: (Toggle Plain Text) using namespace std; using namespace std; __________________ Programming Tutorials - Linux Installation Guide - Learn Python - Learn C++ Got Slack? Join us at #programmingforums @ irc.freenode.net! My software never has bugs. It just develops random features.

Nov 21st, 2005, 7:51 AM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	As Andros said, "::" is the scope (not ownership) resolution operator. With that terminology, you should be able to find what you were looking for. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Nov 21st, 2005, 12:27 AM	#4
BrinyCode Newbie Join Date: Nov 2005 Posts: 11 Rep Power: 0	Well you made a couple good points that lead for me to ask: 1. Classes ( I this as it name it implies) 2. ownership operator (Does it really mean ownership?) 3. Also why do we see "std" with it some times. Just to let you know I am not Pro, just in video game development and relatively new to the C++ language in case I sound like a noob. That's because I am a noob when it comes to the C++ language.

Nov 21st, 2005, 1:12 AM	#5
andro Professional Programmer Join Date: Oct 2005 Location: California Posts: 316 Rep Power: 4	Ermm, :: is the scope resolution operator.

Nov 21st, 2005, 3:27 PM	#9
BrinyCode Newbie Join Date: Nov 2005 Posts: 11 Rep Power: 0	Quick question, why the word scope and if we did not use them what would happen?

Nov 21st, 2005, 4:10 PM	#10
Cache Hobbyist Join Date: Sep 2005 Posts: 266 Rep Power: 4	Here are some definitions of the word "scope": 1. Breadth or opportunity to function. 2. The area covered by a given activity or subject. I'm very new to programming, so if I can understand "why the word scope" from it's definition, I'm sure you can too. I think from that you can also assume what may happen if you try to use an object without bringing it into scope, from outside it's "opportunity to function", the "area covered by a given activity or subject". Perhaps someone else will give you a more technically sound answer but I think it's good practice to look at the definition of words you use if you don't understand why you are using them.

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Programming Forums > Application Development > C++

What are these symbols ---> ::