cmake enable g++ -std=c++11

I have a c++ project and I use cmake to build it. in the c++ code I use std::to_string and apparently I have to path the command g++ -std=c++11to compile it.

I tried :

ccmake .. CMAKE_CXX_COMPILER=g++ -std=c++11

but I have an error that it's looking for a folder std=c++11 in the build directory.

How can I enable c++11 using cmake ?