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c++typesscientific-notation

scientific notation's type

int s = 1e9;

What is type of 1e9 and how precise is it? (Is it exactly equal to 1000000000?)

Printing type of a value/variable to stdout would be useful if it's possible.

Solution

  • 1e9 is a double that has an exact representation in the IEEE floating point representation. The C++ standard doesn't mandate IEEE floating point.

    s is an int, so the double value will be automatically converted to an int. How this takes place is to some extent up to the implementation. On most machines nowadays, this conversion means s will be given an initial value of 1000000000.