~/projects/jruby-cext ➔ g++ test.cpp

~/projects/jruby-cext ➔ ./a.out
102
102

~/projects/jruby-cext ➔ cat test.cpp
#include <stdio.h>

int main(int argc, char** argv) {
  char x = 'f';
  printf("%d\n", (int)x);
  printf("%d\n", int(x));
}