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  1. #include <iostream>
  2. #include <climits>
  3. #include <stdexcept>
  4. #include <cassert>
  5.  
  6. class bitbuffer {
  7.     char buffer;
  8.     char held_bits;
  9. public:
  10.     bitbuffer() :held_bits(0), buffer(0) {}
  11.     unsigned long long read(unsigned char bits) { 
  12.         unsigned long long result = 0;
  13.         //if the buffer doesn't hold enough bits
  14.         while (bits > held_bits) {
  15.             //grab the all bits in the buffer
  16.             bits -= held_bits;
  17.             result |= ((unsigned long long)buffer) << bits;
  18.             //reload the buffer
  19. 			if (!std::cin)
  20.                 throw std::runtime_error("");
  21.             std::cin.get(buffer);
  22.             held_bits = (char)std::cin.gcount() * CHAR_BIT;
  23.         }
  24.         //append the bits left to the end of the result
  25.         result |= buffer >> (held_bits-bits);
  26.         //remove those bits from the buffer
  27.         held_bits -= bits;
  28.         buffer &= (1ull<<held_bits)-1;
  29.         return result;
  30.     };
  31. };
  32.  
  33. int main() {
  34. 	std::cout << "enter 65535: ";  
  35. 	bitbuffer reader;  //0x3635353335
  36. 	assert(reader.read(4) == 0x3);
  37. 	assert(reader.read(4) == 0x6);
  38. 	assert(reader.read(8) == 0x35);
  39. 	assert(reader.read(1) == 0x0);
  40. 	assert(reader.read(1) == 0x0);
  41. 	assert(reader.read(1) == 0x1);
  42. 	assert(reader.read(1) == 0x1);
  43. 	assert(reader.read(4) == 0x5);
  44. 	assert(reader.read(16) == 0x3335);
  45. 	assert(reader.read(8) == 0x0A);
  46. 	std::cout << "enter FFFFFFFF: ";
  47. 	assert(reader.read(64) == 0x4646464646464646ull);
  48.         std::cout << "PASS!";
  49. 	return 0;
  50. }
  51.  
Success #stdin #stdout 0.01s 2692KB
comments (?)
stdin 
65535
FFFFFFFF
stdout 
enter 65535: enter FFFFFFFF: PASS!
https://ideone.com/7PPXq
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
secret

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