> The main reason for asking if A is ok, is that I'm not 100% if A is standard accepted practice by all C++ compilers, and will not cause trouble with some compilers.

A is allowed according to the c++03 standard, so every compiler should support this.

 

> A name introduced by a declaration in a condition (either introduced by the type-specifier-seq or the

> declarator of the condition) is in scope from its point of declaration until the end of the substatements controlled

> by the condition. If the name is re-declared in the outermost block of a substatement controlled by

> the condition, the declaration that re-declares the name is ill-formed. [Example:

> if (int x = f()) {

> int x; // ill-formed, redeclaration of x

> }

> else {

> int x; // ill-formed, redeclaration of x

> }

> —end example]

 

> The value of a condition that is an initialized declaration in a statement other than a switch statement is

> the value of the declared variable implicitly converted to type bool. If that conversion is ill-formed, the

> program is ill-formed. The value of a condition that is an initialized declaration in a switch statement is

> the value of the declared variable if it has integral or enumeration type, or of that variable implicitly converted

> to integral or enumeration type otherwise. The value of a condition that is an expression is the value

> of the expression, implicitly converted to bool for statements other than switch; if that conversion is

> ill-formed, the program is ill-formed. The value of the condition will be referred to as simply “the condition”

> where the usage is unambiguous.

 

But keep in mind that you may not use any additional parentheses or logical operators.

 

Regards,

Markus