Mac Stringstream returns wrong output

Bugi

@fcarney
Agree and have begun to take baby steps with linux (ubunto).
I was dedcated windows user some years ago (before windows 8) and have worked on windows machines afterwards continued.
regarding my school work i have found a windows machine for the moment.
BUT. I am still detement to make it work on mac os. I'm really tired of hearing people say you can't be an engineer with a mac.

and I'm really happy with my mac :(
And although I have a windows machine it doesn't help the others in my class with the same problem (mac user)

fcarney

@Bugi said in Mac Stringstream returns wrong output:

I'm really tired of hearing people say you can't be an engineer with a mac.

The guy I share an office with is an electrical engineer (30+ years), he is a good programmer, uses a Mac, but runs most of his analysis software and programming tools on a VM running Windows 10. I run Linux and use a VM to run Windows 10 for doing Windows development in Qt. Most of my time is in Linux though. So, there is nothing wrong with a Mac. However, no matter what you run, you will probably need a VM to run something else. Or your boss will make a decision that forces you to run a VM. Its just how it goes.

kshegunov

@Bugi said in Mac Stringstream returns wrong output:

Okay maybe we found something here ...
but since I still have very little code experience I don't know if it is something or not... Or for that matter what it means

It means one of two things:

You're reading past the end of stream.
You're reading formatted input (the >> operators), which is not formatted according to the expectation; i.e. there's something wrong while reading from the stream.

Kent-Dorfman

just for grins...please replace std:stringtream with std::istringstream and retest. Since you are only using the stream for input, you should use the istream specialization intended for that purpose.

JKSH

@Bugi said in Mac Stringstream returns wrong output:

ios_base::clear: unspecified iostream_category error
libc++abi.dylib: terminating with uncaught exception of type std::__1::ios_base::failure: ios_base::clear: unspecified iostream_category error

Someone found a bug in clang's stringstream exception detection before (http://clang-developers.42468.n3.nabble.com/libc-ios-base-and-exceptions-td4038960.html ); it's quite possible that your compiler has a buggy implementation of stringstream. This would explain why everyone on this forum was unable to reproduce your issue, yet all 6 macOS users in your class have the same issue.

Unless you have a way to try a different compiler on your macOS, you'll have a hard time proving or disproving that the bug is in your compiler.

Does this exercise require you to use stringstream? If not, try a different way of parsing the string.

JKSH

Anyway, in situations like this, it is useful to create minimal test cases to investigate the issue.

int main() {
    std::string pstr = "22x^3+2x^2-1x^0";
    std::stringstream ss(pstr);

    double coeff = -42.0;
    ss >> coeff;
    std::cout << coeff << std::endl;
}

What does this print for you? If it's the wrong value, what happens if you replace pstr with "22"?

Konstantin Tokarev

@JKSH said in Mac Stringstream returns wrong output:

Unless you have a way to try a different compiler on your macOS, you'll have a hard time proving or disproving that the bug is in your compiler.

However, it would be wise to update Xcode to the latest available version before investigating further

Bugi

@Bugi

I have some exams the next 2 weeks. so the problem is paused :( i will be back and thanks for the help until now

wraitii

I've ran in the same problem in 0 A.D. (see here).

Edit: this is in fact a difference between libstd and libc and it has been reported before: https://bugs.llvm.org/show_bug.cgi?id=17782

Konstantin Tokarev

@wraitii Thanks for information! You've probably meant libstdc++ and libc++, because libc is kinda different thing