The code in general programming languages like Java and C++ and code is usually compiled and tested in IDEs. In other scripting languages, it's common to see a REPL (read-eval-print loop) language shell -- interactive interpreter.
REPL environment allows us to run the code piece by piece. This is very handy for testing purpose sometimes. Now there are some solutions in Java and C++.
[My thinking of picking a pair of similar tools comes from Hotelling's law -- "Linear City Model", though many more other tools are available, too.]
1. cint and igcc are two REPL simulators for C/C++.
2. javarepl and Eclipse's "scrap book" are two REPL simulators for Java.
3. ideone, codechef, and coding-ground provide online compiler suites for various programming languages(C++, Java, Scala, R, Python) by using cloud computing technologies.
4. cppcheck and cpplint.py are two tools for C++ static code analysis.
Coding ground is my favorite. It supports almost all popular languages, and claims 100% cloud. Best of all, it displays the command line and allows me to change the compiling options!
* As of December 2015, coding ground works well on my PC. It has an Android app for Tutorialspoint, but it's slow and Coding Ground on my Galaxy Note 4 is not working as well as it is on PCs.