How the first array entry differs from the second

Question

I can not understand the difference between the declaration with array initialization in the first case and the second

int[] array = new int[3] { 1, 2, 3 };
int[] secondArray = { 1, 2, 3 };

They seem to do the same thing, maybe they work differently?

Answer 1

The is no difference in the result between the two show lines shown:

int[] array = new int[3] { 1, 2, 3 };
int[] secondArray = { 1, 2, 3 };

However, there are practical differences between new int[n] {...} syntax and {...}:

1. Implicit type is not available for the alternative array initialiser:

   var a1 = new int[3] { 1, 2, 3 }; // OK
   var a2 = { 1, 2, 3 }; // Error: Cannot initialize an implicitly-typed variable with an array initializer
   
   // BTW. You can omit the size
   var a3 = new int[] { 1, 2, 3 }; // OK
   

2. With the alternative syntax you cannot specify the size, it's always inferred.

   var a1 = new int[100]; // Array with 100 elements (all 0)
   int[] a2 = { }; // Array with no elements
   

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