constructor with/without semicolon

[thomas]

for the following code, line L can also be written as
A(int i):data(i){}; // L1
A(int i):data(i){} // L2

As I know, L2 works because it's a function;
but how can L1 work? It seems to be a declaration.

---code---
#include<iostream>
using namespace std;

class A{
int data;
public:
A(int i):data(i){} // L
void B(){
cout<<data<<endl;
}
};

int main(){
A(3).B();
}

---code--

 

[Ian Collins]

for the following code, line L can also be written as
A(int i):data(i){}; // L1
A(int i):data(i){} // L2

As I know, L2 works because it's a function;
but how can L1 work? It seems to be a declaration.

No, the semicolon is simply superfluous.

 

[Marcel Müller]

for the following code, line L can also be written as
A(int i):data(i){}; // L1
A(int i):data(i){} // L2

As I know, L2 works because it's a function;
but how can L1 work? It seems to be a declaration.

A constuctor/destructor is a function too. A Function without a return
value of course. And like outside a class definition a function
implementation requires no semicolon. Compare it to:

A::A(int i)
: data(i)
{ // empty
}
^ Here is usually no semicolon too.


Marcel

 

[James Kanze]

thomas schrieb:

A constuctor/destructor is a function too. A Function without a return
value of course. And like outside a class definition a function
implementation requires no semicolon. Compare it to:

A::A(int i)
: data(i)
{ // empty}

^ Here is usually no semicolon too.

With a slight difference: a semicolon after a function
definition outside of the class is illegal. One after a
function definition inside the class is explicitly permitted.
(I think most compilers allow one after the function definition
outside the class as well, as an extension. Logically, it
creates an empty statement, and the only reasons for forbidding
empty statements at namespace scope are historical.)