need help

[Ehsan_MF]

Class A { A() //Constructor } class B: public A { B(...):A(...) {...} . . . } Any body know what is instruction "B(...):A(...)" in class B doing ?

Beginner

[toxcct]

1. you'll have to speak a better english if you want people here to understand you. 2) when providing a code sample, place it between <pre></pre> html tags so that it will be well formatted. 3) a function with the same name as a class is called a constructor. it's purpose is to initalize its members. you should really consider buying a C++ book and learn about object oriented programming...

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[Cedric Moonen]

Yes, in the constructor of B, you call the constructor of A. It is usefull for example when you need to pass arguments to the constructor of A.

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Cédric Moonen Software developer
Charting control [v1.2]

[Ehsan_MF]

What is difference between

B(...):A(...)
{
.
.
.
}

and

B(...)
{
A(..);
.
.
.
}

Beginner

[Cedric Moonen]

The second syntax is invalid: the base class (A) needs to be constructed before your child class (B). So the only way to do that is to put it in the constructor initialisation list.

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Cédric Moonen Software developer
Charting control [v1.2]

[Ehsan_MF]

thank you

Beginner