When I write #include iostream in tinkercad, an error shows up saying "fatal error: iostream: No such file or directory" How can I fix this? full code
Arduino environments generally do not support normal C++ headers like iostream (or e.g. vector). I.e., they do generally not offer support for standard library headers, though some may have been ported.
You may want to try basic Arduino tutorials and the "Blink" sketch as well as basic "Serial" examples (e.g. how to use Serial.println()).
Also, in the future please read the guidelines about a "Minimal, Reproducible Example" and post it as text, not as image (or post the image additionally, I suppose, as it may help). Welcome to StackOverflow!
