() Operator (C# Reference)
In addition to being used to specify the order of operations in an expression, parentheses are used to specify casts, or type conversions:
double x = 1234.7; int a; a = (int)x; // cast double to int
The () operator cannot be overloaded.
For more information, see.
A cast expression can lead to ambiguous syntax. For example, the expression (x)–y could either be interpreted as a cast expression (a cast of –y to type x) or as an additive expression combined with a parenthesized expression, which computes the value x – y.