Create an array in a function in C++ without a global variable

Question

So I would like to create an array in a function with the size set by a number coming in as the parameter. Here is an example:

void temp_arr ( const int array_size ) {
     int temp_arr[array_size]; //ERROR array_size needs to be a constant value
    //Then do something with the temp arr
}

Even if the parameter is a const int, it will not work. I would like to not use a global const and not use vectors. I am just curious as I am learning C++. I would like for it to make it so that the array size is different each time the function is called. Is there a solution to this or am I to create a const variable and the array before the function is called?

Answer 1

Using a template function:

template<std::size_t array_size>
void temp_arr()
{
    int temp_arr[ array_size ];
    // ...work with temp_arr...
}

You can then call the function with this syntax:

temp_arr<32>(); // function will work with a 32 int statically allocated array

Note

Every call with a different value of array_size will instantiate a new function.

Answer 2

When you pass a value in this function, the value is not a constant. Defining an array must be done with a constant value. Although you have used const int array_size, that only creates an integer that is constant within the function. So in a way, if you pass a variable value in the function, it takes it as a variable. Thus it produces an error. Yes, you are to create a constant and pass it during the function call.