"In computer science, functional programming is a programming paradigm—a style of building the structure and elements of computer programs—that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. It is a declarative programming paradigm, which means programming is done with expressions[1] or declarations[2] instead of statements."
Key phrase: "avoids changing-state and mutable data."
You can use C++ as if it was a functional language just like you can use LISP and CaML as if variables were mutable. However in both cases you are bending the language to follow a paradigm that is NOT functional.
Read the first line:
"In computer science, functional programming is a programming paradigm—a style of building the structure and elements of computer programs—that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data. It is a declarative programming paradigm, which means programming is done with expressions[1] or declarations[2] instead of statements."
Key phrase: "avoids changing-state and mutable data."
You can use C++ as if it was a functional language just like you can use LISP and CaML as if variables were mutable. However in both cases you are bending the language to follow a paradigm that is NOT functional.