Most scripting languages have REPLs (read-eval-print-loop) - an interactive console.
by Viktor Kirilov
From the article:
Ever wanted to modify some value or execute some (complex) statement while your C++ program is running just to test something out? Something that cannot be done through the debugger or wouldn’t be trivial? Scripting languages have REPLs and it's time for C++ to get one too.