learn c online code example

Example 1: c

#include 

int main() {
   printf("Hello, world!");
   return 0;
}

I Personally Like 
https://www.programiz.com/c-programming/online-compiler/

You can try https://www.onlinegdb.com/ this as well, works really well for me.
You can also save code there.

i reccomend online gdb https://www.onlinegdb.com/online_c_compiler

replit.com is your best shot tbh