above code to calculate anemometer wind speed using frequency counter library ,i receive below error message
windspeedcode2:15: error: 'FreqCount' is not a class, namespace, or enumeration
FreqCount::f_comp= 8; // Set compensation to 12
windspeedcode2:16: error: 'FreqCount' is not a class, namespace, or enumeration
FreqCount::start(100); // Start counting with gatetime of 100ms
windspeedcode2:17: error: 'FreqCounter' has not been declared
while (FreqCounter::f_ready == 0) // wait until counter ready
windspeedcode2:19: error: 'FreqCount' is not a class, namespace, or enumeration
freq=FreqCount::f_freq;//read frequency value
exit status 1
'FreqCount' is not a class, namespace, or enumeration
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You are using the FreqCount library incorrectly (in fact, I don't think that syntax is valid outside of a class definition...). See the documentation/examples that come with it. You didn't post a link to where you got it (ideally the github so we can see the code w/out downloading anything), so I couldn't help further.
Note that the name of a library is insufficient to identify what library you're using. There are often many versions of a library with subtle (or not so subtle) differences, but the same name, thanks in part to how easy github makes it to fork a repo (often these forks don't even change the readme)