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  1. #include <iostream>
  2. #include <typeinfo>
  3. int main()
  4. {
  5.     int a[3][4] = { {1, 2, 3, 4} , {5, 6, 7, 8}, {9, 10, 11, 12}};
  6.     int n = sizeof(a)/sizeof(a[0]);
  7.     int m = sizeof(a[0])/sizeof(a[0][0]);  
  8.     int *end = a[0] + n * m - 1;
  9.  
  10.     std::cout << typeid(a).name() << "\n";
  11.     std::cout << typeid(a[0]).name() << "\n";
  12.     std::cout << typeid(a[0][0]).name() << "\n";
  13.     std::cout << typeid(end).name() << "\n";
  14.  
  15.     std::cout << "sizeof(a)/sizeof(a[0])\t" << sizeof(a) << "/" << sizeof(a[0]) << "\n";
  16.     std::cout << "sizeof(a[0])/sizeof(a[0][0])\t" << sizeof(a[0]) << "/" << sizeof(a[0][0]) << "\n";
  17.     std::cout << "sizeof(int)\t" << sizeof(int) << "\n";
  18.     std::cout << "sizeof(end)\t" << sizeof(end) << "\n\n";
  19.  
  20.     int** b = new int*[3];
  21.     b[0] = new int[4];
  22.  
  23.     std::cout << typeid(b).name() << "\n";
  24.     std::cout << typeid(b[0]).name() << "\n";
  25.     std::cout << typeid(b[0][0]).name() << "\n";
  26.     std::cout << typeid(b).name() << "\n";
  27.  
  28.     std::cout << "sizeof(b)/sizeof(b[0])\t" << sizeof(b) << "/" << sizeof(b[0]) << "\n";
  29.     std::cout << "sizeof(b[0])/sizeof(b[0][0])\t" << sizeof(b[0]) << "/" << sizeof(b[0][0]) << "\n";
  30.     std::cout << "sizeof(int)\t" << sizeof(int) << "\n";
  31.     std::cout << "sizeof(b)\t" << sizeof(b) << std::endl;
  32.  
  33.     delete [] b[0];
  34.     delete [] b;
  35. }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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A3_A4_i
A4_i
i
Pi
sizeof(a)/sizeof(a[0])	48/16
sizeof(a[0])/sizeof(a[0][0])	16/4
sizeof(int)	4
sizeof(end)	8

PPi
Pi
i
PPi
sizeof(b)/sizeof(b[0])	8/8
sizeof(b[0])/sizeof(b[0][0])	8/4
sizeof(int)	4
sizeof(b)	8
https://ideone.com/wU5C0F
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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