int vs无符号int vs size_t

Question

Starting with a more advanced C++ course, we have to implement an own Matrix, which is typical for first exercises. We received a skeleton to work on and i have got only one question left. The type of the access and size variables.

Here a simple constructor for 1D Matrix, with some Checking of the size.

Array::Array( int xSize )                                                                                     
{                   
    CHECK_MSG(xSize > 0, "Array size too small");
    array_ = new real[xSize];
    size_ = xSize;  
}

Does it make sense to use a size_t or unsigned int instead of an int? After reading the definition of size_t i would tend to use it instead. However in many codes i see just ints everywhere. Is it a java-like coding style? Has size_t any disadvantages i missed?

Edit:

The main question relates to the coding style. I fully understand the difference of size_t and (unsigned) int, as it was already explained here: unsigned-int-vs-size-t

Answer 1

The C++ standard library would almost certainly use a std::size_t for such a type.

Using a signed type is obviously not desirable and, ideally, you want to use a type that lends itself well to having an object that supports iterability.

From the outset I recommend you use typedef std::size_t MySize; within your class, mainly to future-proof yourself. That would be the most sensible choice.

Answer 2

Can the size of anything ever be negative? No, so use unsigned for xSize to express the intent of the code more explicitly.

If you need it be able to handle really big sizes, use size_t .