If you want to round it to lower, just cast it.
float my_float = 42.8f;
int my_int;
my_int = (int)my_float; // => my_int=42
For other purpose, if you want to round it to nearest, you can make a little function or a define like this:
#define FLOAT_TO_INT(x) ((x)>=0?(int)((x)+0.5):(int)((x)-0.5))
float my_float = 42.8f;
int my_int;
my_int = FLOAT_TO_INT(my_float); // => my_int=43
Be careful, ideally you should verify float is between INT_MIN and INT_MAX before casting it.