>?=

[la8dm]

Is ">?=" an operator of C++? Or G++? What is the difference between G++ and C++?
How to search">?=" (i mean some special signs) in Google? Thanks a lot!

Happy Weekend!
Alex

[programmingnewb]

>?= is no operator of C++.

these are operators of C++ :

== (equals to)
!= (does not equals to)
<= (less than or equals to)
>= (greater than or equals to)
< (less than)
> (greater than)
&& (AND)
|| (OR)

I'm sure there are few more, but these are the ones I know.
As for your question about the difference between C++ and G++,

I believe G++ is the C++ compiler of GNU. Anyway before you start programming, read the introduction on tutorials site, they explain what C++
is, and what you can do with it.

Anyway, Hope it helped ya

[la8dm]

Hey,dude!
">?=" is an operator of C++, at least of "DEV C++ 4.9.9.2"
I did an experiment and figured it out that it equals:
"a>?=b " == " if(a>b) 'do nothing' else a=b;"
You can try it and post your feedback.
best,
Alex Lu

[AzraelUK]

I've just updated my code on this question:
http://cplusplus.com/forum/beginner/71/

to use this crazy notation.

(a >?= b;) == (a = max(a, b);)
(a <?= b;) == (a = min(a, b);)

I'm using Code::Blocks, it works fine here too.

[dirk]

A brand new operator? Wicked!
It's overloadable too (of course).
I wonder if there are more?

#include <iostream>
using namespace std;

class Cls {
    int n;
  public:
    Cls(int n_) { n = n_; }
    Cls& operator>?(Cls &b) { return ((n > b.n) ? *this : b); }
    friend ostream& operator<<(ostream &os, Cls &a);
};

ostream& operator<<(ostream &os, Cls &a) {
    return (os << '{' << a.n << '}');
}

int main() {
    int a = 3, b = 5;

    cout << (a >? b)           <<' '<<
            ((a > b) ? a : b)  <<' '<<
            max(a, b)          << endl;

    Cls ca(a), cb(b);
    cout << (ca >? cb) << endl;
}

[Aepos]

Yeah, I know ">?=" is an operator, but, as previously stated, I've only seen it in 4.9.9.2, as this is the only Compiler and IDE that I use.

As for you, programmingnewb, those are the common mathematical operators, but, if you read the help topics, there are more operators such as "+=" (used in appending strings) and ">?=", as used as a mathematical operator and variable manipulator. As for the precise function, I'm unaware. la8dm seems correct, however.

- Aepos

[maingeek]

It's one of a few shorthand notations. This particular one is shorthand for if-then-else...

[dirk]

Just to keep things honest here, it is definitely not shorthand for "if then else".

a >? b           // expression evaluating to the greater of a or b
a >?= b         // combined with assignment which just means ...
a = a >? b      // ... assign greater of a or b to a 

<? is similar but for less than.

To Aepos, do you know any more of these "new" operators?

[maingeek]

Actually, dirk the '?' is an alternative for the if-else statement.

"You can use the ? operator to replace if-else statements of the general form:
if (condition) expression;
else expression;
However, the target of both if and else must be a single expression-not another statement. The ? is called the ternary operator because it requires three operands. It takes the general form:
Exp1 ? Exp2 : Exp3
...The value is determined as follows: Exp1 is evaluated, if it is TRUE then Exp2 is evaluated, if it is FALSE, Exp3 is evalutated." (The Complete Reference C++ Fourth Edition, Herbert Schildt, pg63)

So unless I am reading this incorrectly, it would be a shorthand notation for my if-then-else statement.

~maingeek.

EDIT-I am not meaning to start a flame war, I am merely trying to expand my own understanding of the C++ language in addition to that of other people.

[muzhogg]

A piece of sample code;

#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int a, b;
    cout << "Enter any two integers: ";
    cin >> a >> b;
    
    int c = a > b ? a : b;  // If a > b THEN c = a ELSE c = b
    
    cout << "\nUsing [ c = a > b ? a : b ]";
    cout << "\n\n     The larger of the two numbers is " << c << "\n\n";
    
    // same as;
    cout << "\nUsing [ if (a > b) ... else ... ]";    
    if (a > b) cout << "\n\n     The larger of the two numbers is " << a;
    else cout << "\n\n     The larger of the two numbers is " << b;
    cout << "\n\n\n";
    
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Note that a BIG difference between using [exp1 ? exp 2 : exp3] and [if...else...] is that the first is NOT just a conditional statement, but actually returns a value, so you CAN;

variable = exp1 ? exp 2 : exp2

but you can't

variable = if (exp1) { ... }
           else { ... }

Although, of course, you could put variable assignments in your if...else... structure (if (exp1) { variable = a } else { variable = b })

[maingeek]

Muzhogg,

Ok, I think I am beginning to understand how this is working. The only other time I have seen this in an actual program was in class, when we were using it with a return statement, which is exactly as you described. Thank you very much.