> > *The ints and floats inside the loop are not a problem. Only one of each > is allocated on the stack when the function is entered, and then they're > assigned each time through the loop. Perfectly fine (and good practice for > limiting the scope of variables).*
This would assume you know which compiler is being used, and you've actually disassembled the executable to see what the compiler does. Generally, it is a bad idea to assume you know what is happening. Because of this ambiguity, it is considered bad form. A while statement has no concept of scope. So main() has scope whether inside the while statement, or not. On Sat, Jan 2, 2016 at 3:45 AM, Rick Mann <rm...@latencyzero.com> wrote: > What version of the kernel are you using? There's a problem with some of > them. > > The ints and floats inside the loop are not a problem. Only one of each is > allocated on the stack when the function is entered, and then they're > assigned each time through the loop. Perfectly fine (and good practice for > limiting the scope of variables). > > > On Jan 1, 2016, at 21:08 , William Hermans <yyrk...@gmail.com> wrote: > > > > It's been a while since I've written anything in C++, but I notice > you're not doing any error checking on your filestream. For instance check > out the very simply code listing I demonstrate here ( in C ). > http://www.embeddedhobbyist.com/2015/10/beaglebone-black-adc/ > > > > Notice that I'm checking if length is -1, and if so, moving code > execution back up to the top of the loop. Using continue. You should be > doing something similar( whatever filestream allows ). Also, I've not idea > how filestream works in Linux, but if you're opening a new file descriptor > every function call, you'll want to refactor that out. e.g. you get your > file descriptor only once when the executable is first run, and then > operate off that. > > > > Another thing that you have not really asked about but deserves mention. > You're declaring 2 int's and two floats every program loop. You'll want to > fix that . . . > > > > On Fri, Jan 1, 2016 at 9:26 PM, Sunny Sharma <sunnysharm...@gmail.com> > wrote: > > Hi friends, > > > > I am trying to voltage values from 2 analog sensors which are connected > to pins AIN0 and AIN1 using C++. I have taken Derek Molloy's code for > reading one voltage value and edited it to add a second pin to read values > from. The code is as follows: > > > > #include<iostream> > > #include<fstream> > > #include<string> > > #include<sstream> > > #include<cmath> > > using namespace std; > > > > #define LDR_PATH "/sys/bus/iio/devices/iio:device0/in_voltage" > > > > int readAnalog(int number){ > > > > stringstream ss; > > > > ss << LDR_PATH << number << "_raw"; > > > > fstream fs; > > > > fs.open(ss.str().c_str(), fstream::in); > > > > fs >> number; > > > > fs.close(); > > > > return number; > > > > } > > > > int main(int argc, char* argv[]){ > > > > cout << "Starting the IR distance sensor program:" << endl; > > > > while(1) { > > > > int value0 = readAnalog(0); > > int value1 = readAnalog(1); > > float V0 = ((float)value0 / 4096) * 1.8; > > float V1 = ((float)value1 / 4096) * 1.8; > > > > cout << "Sensor0 is: " << V0 << " Sensor1 is: " << V1 << '\r' << > flush; > > > > usleep(100000); > > > > } > > > > return 0; > > } > > > > However, when I run this code, after 10-15 successful iterations, I > receive this error message: > > > > terminate called after throwing an instance of 'std::ios_base::failure' > > what(): basic_filebuf::underflow error reading the file > > Aborted > > > > I am not sure as to why I am receiving this error, or really what this > error message even means. My guess it is some access error when trying to > read the pin value. > > > > The Adafruit BBIO python library actually found a work around this issue > in C, but I'm not sure how I can extrapolate this to C++ (see: > https://github.com/adafruit/adafruit-beaglebone-io-python/blob/master/source/c_adc.c > ) > > > > If anyone has any insight or help they could offer, that would be very > helpful! > > > > Thanks > > > > -- > > For more options, visit http://beagleboard.org/discuss > > --- > > You received this message because you are subscribed to the Google > Groups "BeagleBoard" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to beagleboard+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > > > > > -- > > For more options, visit http://beagleboard.org/discuss > > --- > > You received this message because you are subscribed to the Google > Groups "BeagleBoard" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to beagleboard+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > > -- > Rick Mann > rm...@latencyzero.com > > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
