How to check if an int on predefined list of values?

[arcull]

Hi everybody. I wonder if in C++ or Qt there is some simple way to check if an int equals to some int from a predefined list. I mean something like pseudo code below. Much thanks.


int a = 3;
int b = 8;
int c = 20;

int x = 5;

if (x in [a,b,c]) {
//further processing
}

if (x in [2,7,5]) {
//further processing
}

[anda_skoa]

Yes.

For example, if the list is a QVector, it has a contains() method.
Or in a QSet if the values are not needed in an ordered fashion.

Similar for STL containers.

Cheers,
_

[arcull]

Thanks, I guess I got it, but it still feels awkward, is there some shorter way, please post a short snippet, thanks.


QVector<int> vec1(QVector<int>(5));
vec1[0] = 1;
vec1[1] = 2;
qDebug() << "vec1 contains:" << vec1.contains(2);

[anda_skoa]

It depends.

You can do things like this


QVector<int> vec = QVector<int>() << 1 << 2;
QSet<int> set = QSet<int>() << 1 << 2;

or


typedef QVector<int> IntVector;
typdef QSet<int> IntSet;
IntSet vec = IntVector() << 1 << 2;
IntSet set = IntSet() << 1 << 2;

with C++11 even


auto vec = IntVector() << 1 << 2;
auto set = IntSet() << 1 << 2;

maybe even


auto vec = IntVector{ 1, 2 };
auto set = IntSet{ 1, 2 };


Cheers,
_

[arcull]

Very good, much thanks ;)