Meaning of intrinsic type with () in C++

Question

What does it mean when an intrinsic type has the parenthesis operators with it.

e.g. int() or float()

Is it like a default constructor or does it have a different meaning for intrinsic types?

----edit----

To add more context:

In my school textbook for C++, I am on a chapter about Templates. A template being used for demonstration is a Table template (a 2D array). One of the functions for Table is a resize method to change the dimensions of the table and is also used in some constructors used for Table. The constructor in question and the resize method are:

template <typename T> 
Table<T>::Table<T>(int m, int n) 
{  
    mDataMatrix = 0;  
    mNumRows    = 0;  
    mNumCols    = 0;  
    resize(m, n, T()); 
}

and

template <typename T> 
void Table<T>::resize(int m, int n, const T& value) 
{  
    // Destroy the previous data.
    destroy();   

    // Save dimensions.  
    mNumRows = m;  
    mNumCols = n;   

    // Allocate a row (array) of pointers.  
    mDataMatrix = new T*[mNumRows];   

    // Now, loop through each pointer in this row array.  
    for(int i = 0; i < mNumRows; ++i)  
    {   
        // And allocate a column (array) to build the table.   
        mDataMatrix[i] = new T[mNumCols];    

        // Now loop through each element in this row[i]   
        // and copy 'value' into it.   
        for(int j = 0; j < mNumCols; ++j)    
            mDataMatrix[i][j] = value;  
    } 
} 

In the constructor definition, resize's third argument is T() (and I assume T becomes whatever the specified type for the template is).

In the definition for resize, T() is used for the value argument to assign a default value to the elements in the table.

From some of the earlier answers, this is zero-initialization. I assume that means the value is 0 for each element in the table (or some equivalent of 0 if the type is a string, I guess). Is this correct?

Answer 1

That is value initialization.

e.g. auto x = int(); means int x = 0

In the example provided T() will create an object of type T and pass it as a parameter.

You could also write:

resize(m, n, T{}); 

Answer 2

Acutally, your code does something different than when you're declaring just a int or a float. It zero initialize the numbers.

example, those three lines are equivalent:

int a = int();

int a = int{};

int a{};

All those three are zero initialized.