Pointer Discrepancy between vc++ & g++

  1 #include 
  2
  3 using namespace std;
  4
  5 int main()
  6 {
  7         int a = 1, b = 2;
  8         int *x;
  9
 10         cout << "x: " << x << '\t';
 11         cout << "*x: " << *x << '\t';
 12         cout << "&x: " << &x << '\t';
 13
 14         cout << endl;
 15
 16         x = &a;
 17         cout << "x = &a" << '\t';
 18         cout << "x: " << x << '\t';
 19         cout << "*x: " << *x << '\t';
 20         cout << "&x: " << &x << '\t';
 21
 22         cout << endl;
 23
 24         x = &a - 1;
 25         cout << "x = &b" << '\t';
 26         cout << "x: " << x << '\t';
 27         cout << "*x: " << *x << '\t';
 28         cout << "&x: " << &x << '\t';
 29
 30         cout << endl;
 31         return 0;
 32 }

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 (VC6++)

modified code...

x = &a  x: 0012FF7C     *x: 1   &x: 0012FF74
x = &a-1  x: 0012FF78     *x: 2   &x: 0012FF74

g++ (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)

x: 0xb7f518dc   *x: -1  &x: 0xbf97f214
x = &a  x: 0xbf97f218   *x: 1   &x: 0xbf97f214
x = &a-1  x: 0xbf97f214   *x: -1080561132 &x: 0xbf97f214

g++ 讓我驚訝！！ 結果 VC++ 2005 Expression 也讓我受精。 XD

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.762 for 80x86

x = &a  x: 0012FF60     *x: 1   &x: 0012FF48
x = &a-1  x: 0012FF5C     *x: -858993460  &x: 0012FF48

Pointer sequence #2

  1 #include 
  2
  3 using namespace std;
  4
  5 int main()
  6 {
  7         int a = 1, b = 2;
  8         int *x;
  9
 10         cout << "x: " << x << '\t';
 11         cout << "*x: " << *x << '\t';
 12         cout << "&x: " << &x << '\t';
 13
 14         cout << endl;
 15
 16         x = &a;
 17         cout << "x = &a" << '\t';
 18         cout << "x: " << x << '\t';
 19         cout << "*x: " << *x << '\t';
 20         cout << "&x: " << &x << '\t';
 21
 22         cout << endl;
 23
 24         x = &b;
 25         cout << "x = &b" << '\t';
 26         cout << "x: " << x << '\t';
 27         cout << "*x: " << *x << '\t';
 28         cout << "&x: " << &x << '\t';
 29
 30         cout << endl;
 31         return 0;
 32 }

g++ (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)

x: 0xb7f078dc   *x: -1  &x: 0xbff350c4
x = &a  x: 0xbff350cc   *x: 1   &x: 0xbff350c4
x = &b  x: 0xbff350c8   *x: 2   &x: 0xbff350c4

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 (VC6++)

跑到 line 10 就結束！

then modified code.
x = &a  x: 0012FF7C     *x: 1   &x: 0012FF74
x = &b  x: 0012FF78     *x: 2   &x: 0012FF74

Pointer sequence #1

#include 

using namespace std;

int main()
{
        int a, b, c, d, e;
 int i;

        cout << "Input five numbers: \n";
        cin >> a >> b >> c >> d >> e;
        cout << "A: " << &a << "\nB: " << &b
        << "\nC: " << &c << "\nD: " << &d << "\nE: " << &e;

 cout << endl;
 return 0;
}

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 (VC6++)

1
2
3
4
5
A: 0012FF7C
B: 0012FF78
C: 0012FF74
D: 0012FF70
E: 0012FF6C

g++ (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)

1
2
3
4
5
A: 0xbfdc2cec
B: 0xbfdc2ce8
C: 0xbfdc2ce4
D: 0xbfdc2ce0
E: 0xbfdc2cdc

---

#include 

using namespace std;

int main()
{

        cout << "Input five numbers: \n";
        cin >> a >> b >> c >> d >> e;
        for (i = 0; i < 5; i++)
                cout << "Var" << i << ":\t"
                << &a - i << " : "
                << *(&a - i) << '\n';

 cout << endl;
 return 0;
}

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 (VC6++)

1
2
3
4
5
Var0:   0012FF7C : 1
Var1:   0012FF78 : 2
Var2:   0012FF74 : 3
Var3:   0012FF70 : 4
Var4:   0012FF6C : 5

g++ (GCC) 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)

1
2
3
4
5
Var0:   0xbfdea9e0 : 1
Var1:   0xbfdea9dc : 2
Var2:   0xbfdea9d8 : 3
Var3:   0xbfdea9d4 : 4
Var4:   0xbfdea9d0 : 5

All mail -> Gmail

看到 Yi-Feng Tzeng’s Blog 的 用 Gmail 收取外部郵件後，開始動手設定我的幾個信箱都納入 Gmail 管理。

兩個學術單位信箱，Y! 需要付費才有 POP3 收信功能，加上最近的 spam 都直接進入 inbox，所以想要放棄 Y! 了，目前它的功能只剩下 tw.clubs 和網拍的認證而已。

Gmail 方便至極，不用我多說。哈哈，但是我還是覺得有些改進的空間，找個時間去寫 feedback 給他們。