[~]% cat t.c
#include <stdio.h>
int main(int argc, char** argv)
{
    double f = 9007199254740992;
    printf("f: %f\n",f++);
    printf("f: %f\n",f);
    return 0;
}
[~]% ./a.out
f: 9007199254740992.000000
f: 9007199254740992.000000