CODEWITHSUNDEEP
c++syntax
alfalfa
alfalfa

Reputation: 147

c++ strange syntax

i dont understand some things in a code from a tutorial
first one: what is that comma "," doing in the middle there? is it mb a overloaded operator? 

u32 TimeStamp = irrTimer->getTime(), DeltaTime = 0;

next i have a weird constructor from class CharacterDemo, why is there a ":" following some variables with weird brackets? im guesseing they are beeing initialized with the value in the brackets.. ?

CharacterDemo::CharacterDemo()
:
m_indexVertexArrays(0),
m_vertices(0),
m_cameraHeight(4.f),
m_minCameraDistance(3.f),
m_maxCameraDistance(10.f)
{
    m_character = 0;
    m_cameraPosition = btVector3(30,30,30);
}

im rly curiouse, explanation much appriciated

Upvotes: 1

Views: 361

Answers (2)

ChrisW
ChrisW

Reputation: 56083

what is that comma "," doing in the middle there?

A statement like int i = 3, j = 4; is the same as int i = 3; int j = 4;

So, u32 TimeStamp = irrTimer->getTime(), DeltaTime = 0; is defining and initializing two variables of type u32: one named TimeStamp and the other named DeltaTime.

why is there a ":" following some variables with weird brackets? im guesseing they are being initialized with the value in the brackets.. ?

That's correct: google for c++ member initialization list.

Upvotes: 2

Maël Nison
Maël Nison

Reputation: 7353

It's an initialization list.

It calls the constructors of the members and parent classes of the specified class.

Note that you can only use it in the constructor of a class (because it only happens at its construction).

[edit] For your first question, it's a way to declare multiple variables of the same type at once. Note that it will not always work as expected : int * a, b will declare a variable a of type int *, and another variable b of type int (not a pointer).

Upvotes: 4

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