I'm learning C++ and I'm using g++ on Linux for practicing. 1) I want to know if people working as programmers use g++ -pedantic flag and also it's importance in real world. 2) What about other compilers, do they also allow this? Has this become some de-facto standard? I'm interested because I'm reading C++ Primer where the author points that its illegal to use non-const expression as dimension in array definition and g++ by default allows it. And there might be other things I'm unaware of.