The embedded C I'm using doesn't have a round() function it it's math lib, what would be a concise way to implement this in C? I was thinking of printing it to a string, looking for the decimal place, then finding the first char after the period, then rounding up if >= 5, else down. etc. Was wondering if there's something more clever.
Thanks, Fred
You could re-invent the wheel, as many other answers suggest. Alternately, you could use someone else's wheel -- I'd suggest Newlib's, which is BSD-licensed and intended for use on embedded systems. It properly handles negative numbers, NaNs, infinities, and cases which are not representable as integers (due to being too large), as well as doing so in an efficient manner that uses exponents and masking rather than generally-costlier floating-point operations. In addition, it's regularly tested, so you know it doesn't have glaring corner-case bugs in it.
The Newlib source can be a bit awkward to navigate, so here are the bits you want:
Float version: https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libm/common/sf_round.c;hb=master
Double version: https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libm/common/s_round.c;hb=master
Word-extraction macros defined here: https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=blob;f=newlib/libm/common/fdlibm.h;hb=master
If you need other files from there, the parent directory is this one: https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;a=tree;f=newlib/libm/common;hb=master
For the record, here's the code for the float version. As you can see, there's a bit of complexity required to deal with all the possible cases correctly.
float roundf(x)
{
int signbit;
__uint