Make C floating point literals float (rather than double)

Question

It is well known that in C, floating point literals (e.g. 1.23) have type double. As a consequence, any calculation that involves them is promoted

Answer 1

Use warnings instead: -Wdouble-promotion warns about implicit float to double promotion, as in your example. -Wfloat-conversion will warn about cases where you may still be assigning doubles to floats.

This is a better solution than simply forcing double values to the nearest float value. Your floating-point code is still compliant, and you won't get any nasty surprises if a double value holds a positive value, say, less than FLT_DENORM_MIN (assuming IEEE-754) or greater than FLT_MAX.