Why abs wont work on neg val

[A Former User]

If doing

qint64 n=std::numeric_limits<qint64>::min();
n=qAbs(n);

if(n<0)
It returns true...

But if adding just 1 number its ok.

Why is that?

[JKSH]

@Q139 said in Why abs wont work on neg val:

Why is that?

Because the absolute value of std::numeric_limits<qint64>::min() is greater than std::numeric_limits<qint64>::max().

[Christian Ehrlicher]

See also https://en.cppreference.com/w/cpp/numeric/math/abs :

The behavior is undefined if the result cannot be represented by the return type.