What is a double datatype in C

Question

What are alphanumeric datatype declarations called?

Answer 1

Double data type used to store the decimal numbers.
Ex: double a=12.34567
In C, double is default type to store decimal format numbers..
There is no alphanumeric data type in C.
If you want store, alphanumeric, you can use char array, like a string representation.

Answer 2

Double is for storing decimals like float but float takes upto 6 precision values but double takes upto 8 precision values.