CODEWITHSUNDEEP
c++c++11
ayodele
ayodele

Reputation: 27

C++ Complex library compile error

Here is my code:

#include <iostream>
#include <iomanip>
#include <complex>
#include <cmath>

int main()
{

using namespace std::complex_literals;

std::cout<< std::fixed<<std::setprecision(1);

std::complex<double> z1= 1i *1i;   //imaginary unit squared
std::cout<<"i * i= " <<z1 <<'\n';

std::complex<double> z2=std::pow(1i, 2); //imaginary unit squared
std::cout <<"pow(i,2) =" <<z2 <<'\n';


}

I compile with gcc hello.cpp -lstdc++ -o hello.o

Basically it won't let me double the powers of a complex number when i do std::complex z2=std::pow(1i, 2);..

I get the following error

error: no matching function for call to 'pow(complex int, int)' std::complex z2=std::pow(1i, 2);

However, if i remove the complex number and do std::complex z2=std::pow(2, 2);

it returns 4, the correct answer..

There are many more lines of compile errors, but i made it brief

Upvotes: 0

Views: 3033

Answers (3)

Gabriella Giordano
Gabriella Giordano

Reputation: 1238

This answer follows up the comments to the original question:

you have to force the compiler to use the c++14 standard with the -std=c++14 option because the literal operator""i is part of the C++14 spec.

GCC uses c++14 by default since version 6.1. Check your compiler version with gcc -v and refer to this link for GCC standard support.

EDIT:

I was able to reproduce the compiling issue with GCC 6.3 through the link provided by Mr Richard Critten in the comments to the original question, who was the first to point to the correct answer. My apology because I totally overlooked the reference to the C++14 standard.

Anyway, for the sake of clarity, I'm editing this answer, because I've found something that may be interesting to share.

The reason why compiling with GCC 6.3 fails is the fact that the reference standard has been changed in December 2016 from C++14 to GNU++14, see here.

GNU++14 is an extension to the C++ standard, that, among other things, provides additional functions overload for standard APIs.

I've found that with GNU++14 SFINAE fails in finding a proper overload for the std::pow() functions unless the type is explicitly set in the template call like in the snipped below:

std::complex<double> z2=std::pow<double>(1i, 2);

The GNU++14 includes changes to the cmath and complex header files, that I believe are the cause of the issue. Turning on the C++14 flag, that is not the default anymore, fixes the problem.

Upvotes: 1

ayodele
ayodele

Reputation: 27

So, I installed Microsoft Visual Studio.. I am using the clang compiler and my program ran smoothly with no errors!

Thanks for all the help guys, but i think clang is a better c++ compiler

Upvotes: 0

Aniket Chowdhury
Aniket Chowdhury

Reputation: 343

I don't know why it is not compiling on your system, it runs fine on mine.

I think something is wrong with your compiler. And, not the version. yet you could try std::cout << __cplusplus. See what this prints.

C++11 doesn't recognize std::complex_literals, so doubt that is the case, but yet the compiler still couldn't find the function. I honestly don't understand why it is searching for (complex int, int). The compiler is either corrupt or an old beta version.

You should either download a fresh version of the compiler or run it online somewhere. Try adding -std=c++14, but I doubt that would help.

Try your code here(it works): https://www.jdoodle.com/online-compiler-c++14

Upvotes: 0

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