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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <string>
  4. #include <sstream>
  5. #include <climits>
  6. #include <type_traits>
  7. #include <cstdint>
  8.  
  9. // -----
  10.  
  11. // First option, with `<< "0x"`.
  12. namespace ZeroX {
  13. 	namespace detail {
  14. 	    constexpr int HEX_DIGIT_BITS = 4;
  15.  
  16. 	    template<typename T> struct is_char
  17. 	      : std::integral_constant<bool,
  18. 	                               std::is_same<T, char>::value ||
  19. 	                               std::is_same<T, signed char>::value ||
  20. 	                               std::is_same<T, unsigned char>::value> {};
  21. 	}
  22.  
  23. 	template<typename T>
  24. 	std::string hex_out_s(T val) {
  25. 	    using namespace detail;
  26.  
  27. 	    std::stringstream sformatter;
  28. 	    sformatter << std::hex
  29. 	               << std::internal
  30. 	               << "0x"
  31. 	               << std::setfill('0')
  32. 	               << std::setw(sizeof(T) * CHAR_BIT / HEX_DIGIT_BITS)
  33. 	               << (is_char<T>::value ? static_cast<int>(val) : val);
  34.  
  35. 	    return sformatter.str();
  36. 	}
  37. } // ZeroX
  38.  
  39. // -----
  40.  
  41. // Second option, with `<< std::showbase`.
  42. namespace ShowBase {
  43. 	namespace detail {
  44. 	    constexpr int HEX_DIGIT_BITS = 4;
  45. 	    constexpr int HEX_BASE_CHARS = 2;
  46.  
  47. 	    template<typename T> struct is_char
  48. 	      : std::integral_constant<bool,
  49. 	                               std::is_same<T, char>::value ||
  50. 	                               std::is_same<T, signed char>::value ||
  51. 	                               std::is_same<T, unsigned char>::value> {};
  52. 	}
  53.  
  54. 	template<typename T>
  55. 	std::string hex_out_s(T val) {
  56. 	    using namespace detail;
  57.  
  58. 	    std::stringstream sformatter;
  59. 	    sformatter << std::hex
  60. 	               << std::internal
  61. 	               << std::showbase
  62. 	               << std::setfill('0')
  63. 	               << std::setw((sizeof(T) * CHAR_BIT / HEX_DIGIT_BITS) + HEX_BASE_CHARS)
  64. 	               << (is_char<T>::value ? static_cast<int>(val) : val);
  65.  
  66. 	    return sformatter.str();
  67. 	}
  68. } // ShowBase
  69.  
  70. // -----
  71.  
  72. int main() {
  73. 	uint32_t       hexU32 = 0x0f;
  74. 	int            hexI   = 0x3c;
  75. 	unsigned short hexUS  = 0x12;
  76. 	char           hexC   = 0xf;
  77. 	unsigned char  hexUC  = 0xa;
  78. 	signed char    hexSC  = 0x3;
  79.  
  80. 	std::cout << std::left
  81. 			  << std::setw(22) << "uint32_t:"
  82. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexU32)
  83. 			  << std::setw(23) << '\n'
  84. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexU32)
  85.  
  86. 			  << std::setw(24) << "\n\nint:"
  87. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexI)
  88. 			  << std::setw(23) << '\n'
  89. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexI)
  90.  
  91. 			  << std::setw(24) << "\n\nunsigned short:"
  92. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexUS)
  93. 			  << std::setw(23) << '\n'
  94. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexUS)
  95.  
  96. 			  << std::setw(24) << "\n\nchar:"
  97. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexC)
  98. 			  << std::setw(23) << '\n'
  99. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexC)
  100.  
  101. 			  << std::setw(24) << "\n\nunsigned char:"
  102. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexUC)
  103. 			  << std::setw(23) << '\n'
  104. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexUC)
  105.  
  106. 			  << std::setw(24) << "\n\nsigned char:"
  107. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(hexSC)
  108. 			  << std::setw(23) << '\n'
  109. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(hexSC)
  110.  
  111. 			  << std::setw(24) << "\n\nDecimal rvalues, too:"
  112. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(29)
  113. 			  << std::setw(23) << '\n'
  114. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(29)
  115.  
  116. 			  << std::setw(24) << "\n\nA long long:"
  117. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(LLONG_MAX)
  118. 			  << std::setw(23) << '\n'
  119. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(LLONG_MAX)
  120.  
  121. 			  << std::setw(24) << "\n\nAnd zero:"
  122. 			     << std::setw(18) << "0x version: "       << ZeroX::hex_out_s(0)
  123. 			  << std::setw(23) << '\n'
  124. 			     << std::setw(18) << "showbase version: " << ShowBase::hex_out_s(0)
  125. 			  << "\n\n" << std::endl;
  126. }
Success #stdin #stdout 0s 16088KB
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stdin
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Standard input is empty
stdout
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uint32_t:             0x version:       0x0000000f
                      showbase version: 0x0000000f

int:                  0x version:       0x0000003c
                      showbase version: 0x0000003c

unsigned short:       0x version:       0x0012
                      showbase version: 0x0012

char:                 0x version:       0x0f
                      showbase version: 0x0f

unsigned char:        0x version:       0x0a
                      showbase version: 0x0a

signed char:          0x version:       0x03
                      showbase version: 0x03

Decimal rvalues, too: 0x version:       0x0000001d
                      showbase version: 0x0000001d

A long long:          0x version:       0x7fffffffffffffff
                      showbase version: 0x7fffffffffffffff

And zero:             0x version:       0x00000000
                      showbase version: 0000000000
https://ideone.com/Eg38VK
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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