What does this mean? (double) It's the same things? I know the answer to this, but what role "double"? Double-precision number?

Question

Console. WriteLine(-b/(2*(double)a));
or
Console. WriteLine(-(double)b/(2*a));
//thx☺️

Answer 1

(dataType) is an operator that will cast (cast is a fancy word for convert) whatever is to the right of it to that type.

For example,

float a = 5.5;
int b = (int)a;

A is being casted to an int, making b equal to 5.

One more example:

float d = 5.5;
int e = (int)(d + 2 * 2);

e will cast (5.5 + 2 * 2) to an int.
Making e: 5.5 + 4 = 9.5 = 9.

In your example, we are casting to a double. That way the result can have decimals with high precision.

Answer 2

Precision is the main difference.

Float - 7 digits (32 bit)

Double-15-16 digits (64 bit)

Decimal -28-29 significant digits (128 bit)