g++ 'stod' was not declared in this scope

Question

I am trying to compile the following code using g++ (version 4.8.1) in cygwin, and it seems that it cannot use the function stod():

//test.cpp
#include<iostream>
#include<vector>
#include<string>
using namespace std;

int main(){
    string a="1.23";
    cout<<stod(a);
    return 0;
}

I keep getting this eroor:

test.cpp:9:14: error: 'stod' was not declared in this scope
  cout<<stod(a);

I read another thread that has the same problem. There, people suggested to use c++11 to address it. So I tried both the following commands to compile it but still got the same error:

g++ -std=c++0x test.cpp -o test
g++ -std=c++11 test.cpp -o test

Does anyone know a solution to this problem?

And how do I know that c++11 is enabled? Do I need to modify my code in order to use it?

Thanks a lot!

@101010 `-std=c++0x` and `-std=c++11` do the exact same thing. — , May 10 '16 at 12:40
This is a good question. I copied your code exactly in linux (ubuntu 16.04 and g++ 5.03) and it worked and gave no errors. — Nathaniel Johnson, May 10 '16 at 12:45
This issue is mingw specific. The answer is http://stackoverflow.com/a/16132279/1362568 — Mike Kinghan, May 10 '16 at 13:01

score 2 · Accepted Answer · answered May 10 '16 at 12:42

It works in GCC 4.8 on Coliru (http://coliru.stacked-crooked.com/a/8a68ad0ca64c1bff) and also in Clang on my machine. It could be that somehow your Cygwin system doesn't support this function. I suggest you work around it by simply using good old strtod() instead. That's probably what stod() uses under the hood anyway.

g++ 'stod' was not declared in this scope

1 Answers1