The problem is not Code::Blocks. The problem is your C++ code is incorrect.
return0;
is not valid C++ code to the best of my knowledge. It should be return 0;
. Most likely it was a build error (syntax error). Look down the bottom of the screen for Build Messages
. Click for full size
The default "Console project" in Code::Blocks should work, try that too.
#include <iostream> using namespace std; int main() { cout << "Hello world!" << endl; return 0; }