Linux printf funny

I'm converting an application from Windows console to Linux, and the changeover has gone remarkably easily (considering that I know very little about Linux), until now.

No problem installing GCC, KDevelop, FTDI USB drivers, remarkably few changes to recompile the code... but printf fails after about half-a-dozen calls. A float value prints as "nan"- not a number I asume, rather than what I eat with an Indian takeout. This value is computed from two int values (actually a weight and a tare reading) and multiplied by a scale factor (1.0 for the tests).

The funny thing is that I can't see anything different about the weight or the tare value between instances that print and those that fail. There is the expected one-or-two bits wobble in the weight reading, but the values only oscillate between plus and minus one relative to the tare. Once it fails, it seems to be sticky- it doesn't recover even when the readings are identical to before the nan.

So, please you Linux/ GCC experienced people- what absolutely basic item of knowledge am I lacking?

Paul Burke
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Relevant Pages

  • Re: Linux printf funny
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