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  1. #include <iostream>
  2. #include <typeinfo>
  3. #include <type_traits>
  4.  
  5. int main()
  6. {
  7.     int a[20] = { 1, 2, 3, 4 } ; // array of 20 int
  8.  
  9.     decltype(a) b = { 1, 2, 3, 4 } ; // b is of the same type as a - an array of 20 int
  10.  
  11.     typedef int array_type[20] ; // 'array_type' is an alias for 'array of 20 int'
  12.     using array_type = int[20] ; // 'array_type' is an alias for 'array of 20 int'
  13.  
  14.     array_type c = { 1, 2, 3, 4 } ; // c is an array of 20 int
  15.  
  16.     // b and c are of the same type
  17.     std::cout << std::boolalpha ;
  18.     std::cout << "b and c are of the same type: "
  19.                << std::is_same< decltype(b), decltype(c) >::value << '\n' ; // true
  20.  
  21.     array_type d[5] = { { 1, 2 }, {}, {6} } ; // array of 5 array_type
  22.  
  23.     int e[5][20] = { { 1, 2 }, {}, {6} } ; // array of 5 array of 20 int
  24.  
  25.     // d and e are of the same type
  26.     std::cout << "d and e are of the same type: "
  27.                << std::is_same< decltype(d), decltype(e) >::value << '\n' ; // true
  28.  
  29.     int f[5][15] = { { 1, 2 }, {}, {6} } ; // array of 5 array of 15 int
  30.  
  31.     // d and f are of different types
  32.     std::cout << "d and f are of the same type: "
  33.                << std::is_same< decltype(d), decltype(f) >::value << '\n' ; // false
  34.  
  35.     // an (expression of type) array can be implicitly converted to a pointer,
  36.     // the result of the conversion is a pointer to the first element of the array.
  37.  
  38.     int* p1 = &(a[0]) ; // address of first element
  39.     int* p2 = a ; // a is converted to a pointer, both p1 and p2 point to the first element
  40.  
  41.     std::cout << "p1 == p2 : " << ( p1 == p2 ) << '\n' ; // true
  42. }
  43.  
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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b and c are of the same type: true
d and e are of the same type: true
d and f are of the same type: false
p1 == p2 : true
https://ideone.com/0MiS2g
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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