CINT: The C/C++ Interpreter

CINT is a C/C++ interpreter aimed at processing C/C++ scripts. Scripts are programs performing specific tasks. Generally execution time is not critical, but rapid development is. Using an interpreter the compile and link cycle is dramatically reduced facilitating rapid development. CINT makes C/C++ programming enjoyable even for part-time programmers.

CINT covers about 95% of ANSI C and 85% of C++. CINT, written in ANSI C (about 80000 loc), is solid enough to interpret itself and let the interpreted version execute a program.

There's also Ch, but that seems to be more of a money-oriented product.