c
https://www.codechef.com/ide
https://www.programiz.com/c-programming/online-compiler/
https://workat.tech/ide/online-c-compiler

c++
https://www.jdoodle.com/online-compiler-c++/
https://www.programiz.com/cpp-programming/online-compiler/
http://cpp.sh/
https://www.tutorialspoint.com/compile_cpp_online.php
https://www.w3schools.com/cpp/cpp_compiler.asp
https://www.mycompiler.io/online-c++-compiler