How to set precision for double data type variables in C?

In my program some double variables take values of the form 1.00000001. Equality check of these variables with 1 obviously fails.

I wanted to know how can I reduce the precision of double type variables in c, so that equality with integers works.

Answer

There's no portable way, no.

With the GNU C library, you can use this API to change the rounding mode.

But in general, it's better to express it with code, so that your expectations become clear and portable:

#define EQUALITY_EPSILON 1e-3  /* Or whatever. */


if(fabs(x - y) <= EQUALITY_EPSILON)
{
}