How to specify an array in the C ++ function so that the size of the array is determined by the input value of the function.

How to specify an array in the C ++ function so that the size of the array is determined by the input value of the function.

Today, I debugged A C ++ program and defined a one-dimensional array in a function. The size of the array is determined by the input value of the function.

This is the case:

Int a [r + L-1];

Then, an error is reported!

The error is as follows:

So the question is, must the array size be specified for defining arrays in C ++?

The answer is no. When defining arrays in C ++, we do not have to specify the array size.

However, the array size must be specified to define an array in the Code Editor, because the syntax of this definition array is in the C language (that is, regular array), and the size must be determined.

In C ++, there are two ways to define an array without specifying the size:

1) Use Pointer:

Int * a = new int [r-l + 1];

2) Replace the array with the container vector:

Vector <int>;

A vector is equivalent to a dynamic array and does not need to be specified. In C ++, the regular array is a data structure with a fixed size. It is easy to overflow in some functions and cannot achieve the actual purpose. Therefore, vector is recommended in C ++.

About the usage of vector, You can see another blog Author: https://www.cnblogs.com/yoke/p/6080080.html