Objects of classes double and int are real and integer numbers. These may result from calculations or transformations, or be specified by user. Numbers falling within the range of class double are those with the floating point. The scope of values depends on platform, yet, as a rule, the scopes are
Class double usually has 15 significant digits and doesn't guarantee preservation of numbers in the last orders. Precise number of significant digits depends on the platform you use.
Object of class double can't have NaN or Inf value.