Any difference between !a and a==0?

[CharChen]

Any difference between !a and a==0?

  !a

  a==0

seems to have the same result.

[rafae11]

! means opposite if a is equal to zero it will become one.

== means check if both values are equal. if they are both equal it will result to one.

[MatthewRock]

Yes. It may work for fundamental data types, but if you go for classess, one may overload both ! and == operators, so it may not work as you intend.

[c0defisher]

they typically have the same result only during comparisons , like in loops or if statements , other wise , "!" operator returns the complement of the number a. And of course you cannot use "==" other than during comparison statements. One more thing , the above may be true only if the operators are not overloaded.

[28poGNh0]

You think they are the same , just because they return a boolean value(1 or 0) prof

# include <iostream>
using namespace std;

int main()
{
    int nbr = 1;

    cout << (nbr == 0) << endl;
    cout << !nbr << endl;
    
    return 0;
}

but they are different

== : is a relational and equality operator that evaluates comparaison between two expressions

! : is a logical operator performs boolean operations

some exp

# include <iostream>
using namespace std;

int main()
{
    int nbr = 1;

    if(nbr == 1)// comparaision between nbr and 1
    {
        while(!(nbr == 5))
        {
            cout << "The expression " << nbr << " == 5 is false" << endl;
            nbr++;
        }
        cout << "The expression " << nbr << " == 5 is true" << endl;
        cout << "but !(" << nbr << " == 5) is false that\'s why while loop ended" << endl;
    }

    return 0;
}

hope that helps

[CharChen]

Thanks a lot. ^_^
But I think in this example
while(!(nbr == 5))
can also be replaced with
while((nbr == 5)==0)
to some extent, there is still no difference.

[Peter87]

Both expressions are equivalent if a is an integer or a boolean.