what is the differnece between the two coding styles

[sysabod]

Hi all:
i just saw this,assuming var is a variable.

if(-1 != var){
        ;
}

another common coding style is

if(var != -1){
        ;
}

my question is any difference between the two regarding to efficiency,etc.

thanks in advance.

[sohguanh]

This is a good question I would like to know the answer though.

However C++ allow operator overloading so by swapping them around I am worried it may cause compiler or run-time error.

Usually for operator overloading, we assume the argument is rhs of the class unless we use friend function concept to explicitly cater for argument on the lhs also.

[Duthomhas]

It is a reactive style used to help prevent errors like if (var = -1), which most compilers (until very recently, I believe) blithely accepted in good faith. (Many modern compilers will warn you that an assignment is probably not what you meant to write.)

A properly-overloaded operator will work with the operands on either side. There is no 'usually' other than that; you should have both the member and friend overloads.

Hope this helps.

[sysabod]

@Duoas

according to what you said, i am glad to know that this prevents the most easy-making mistake in c/c++, in other hand, has this nothing to do with efficiency ?

[Athar]

has this nothing to do with efficiency ?

No, not at all.