编译期时立即数溢出

#include
using namespace std;

int main()
{
    int a = +1.0E20; // to hpho: 类似这样的编译期时立即数溢出，标准中有没有什么规定？
    int b = -1.0E20;

    cout << "0x" << hex << a << '(' << dec << a << ')' << endl;
    cout << "0x" << hex << b << '(' << dec << b << ')' << endl;

    return 0;
}

/* gcc3.4.5输出
0x7fffffff(2147483647)
0x80000000(-2147483648)

VC2005输出
0x63100000(1661992960)
0x9cf00000(-1661992960)
*/

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以下在gcc3.4.5中测试：

#include
using namespace std;

int main()
{
    double x = 1.0E20;
    double y = -1.0E20;

    int a1 = x;                   // 0x80000000(-2147483648)
    int b1 = 1.0E20;              // 0x7fffffff(2147483647)

    unsigned int c1 = x;          // 0x0(0)
    unsigned int d1 = 1.0E20;     // 0xffffffff(4294967295)

    int a2 = y;                   // 0x80000000(-2147483648)
    int b2 = -1.0E20;             // 0x80000000(-2147483648)

    unsigned int c2 = y;          // 0x0(0)
    unsigned int d2 = -1.0E20;    // 0x0(0)

    cout << "0x" << hex << a1 << '(' << dec << a1 << ')' << endl;
    cout << "0x" << hex << b1 << '(' << dec << b1 << ')' << endl;
    cout << "0x" << hex << c1 << '(' << dec << c1 << ')' << endl;
    cout << "0x" << hex << d1 << '(' << dec << d1 << ')' << endl;

    cout << "0x" << hex << a2 << '(' << dec << a2 << ')' << endl;
    cout << "0x" << hex << b2 << '(' << dec << b2 << ')' << endl;
    cout << "0x" << hex << c2 << '(' << dec << c2 << ')' << endl;
    cout << "0x" << hex << d2 << '(' << dec << d2 << ')' << endl;

    return 0;
}