sqrt() of int type in C

Question

I am programming in the c language on mac os x. I am using sqrt, from math.h, function like this:

int start = Data -> start_number;
double localSum;

for          


        

Answer 1

The compiler knows the prototype of sqrt, so it can - and will - produce the code to convert an int argument to double before calling the function.

The same holds the other way round too, if you pass a double to a function (with known prototype) taking an int argument, the compiler will produce the conversion code required.

Whether the compiler warns about such conversions is up to the compiler and the warning-level you requested on the command line.

For the conversion int -> double, which usually (with 32-bit (or 16-bit) ints and 64-bit doubles in IEEE754 format) is lossless, getting a warning for that conversion is probably hard if possible at all.

For the double -> int conversion, with gcc and clang, you need to specifically ask for such warnings using -Wconversion, or they will silently compile the code.