18.limits.traps.stdcxx-624.cpp

Go to the documentation of this file.

 
#include <cassert>   // for assert()
#include <csignal>   // for SIGFPE and signal()
#include <cstdlib>   // for strtod()
#include <limits>    // for numeric_limits
 
 
char digits[] = " +0.?23456789e+01";
 
volatile int  result;
 
 
extern "C" {
 
void handle_FPE (int)
{
    // if we get here (presumably in response to SIGFPE triggered
    // by a trap in integer arithmetic) verify that numeric_limits
    // traps is non-zero and successfuly exit the process
    assert (std::numeric_limits<int>::traps);
 
    std::exit (0);
}
 
}   // extern "C"
 
 
#ifdef _MSC_VER
   // use Structured Exception Handling to detect arithmetic exceptions
#  define TRY           __try
#  define EXCEPT(arg)   __except (arg)
#else
#  define TRY              if (1)
#  define EXCEPT(ignore)   else if (0)
#endif   // _MSC_VER
 
 
int main ()
{
    // prevent clever optimizers from figuring out that (zero == 0)
    digits [4] = '0';
    const int zero = (int)std::strtod (digits, 0);
 
    // compute a non-zero integer value
    digits [4] = '1';
    const int non_zero = (int)std::strtod (digits, 0);
 
    // set up a handler for the FPE signal only when traps is true
    // otherwise expect to be able to perform integer arithmetic
    // without a signal
    if (std::numeric_limits<int>::traps)
        std::signal (SIGFPE, handle_FPE);
 
    bool trapped = false;
 
    // if this traps (generates SIGFPE), verify (in the signal handler)
    // that integer arithmetic is expected to trap. if this doesn't trap
    // then we are either on windows, or traps are disabled.
    TRY {
        result  = non_zero / zero;
        result += non_zero % zero;
    }
    EXCEPT (1) {
        // windows structured exception caught
        trapped = true;
    }
 
    // if we get this far, verify that we have caught a structured
    // exception or integer arithmetic is known not to trap
    assert (trapped == std::numeric_limits<int>::traps);
 
    (void)&result;
 
    return 0;
}