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  1. #include <stdio.h>
  2.  
  3. /* Number of bits in inttype_MAX, or in any (1<<b)-1 where 0 <= b < 3E+10 */
  4. #define IMAX_BITS(m) ((m) /((m)%0x3fffffffL+1) /0x3fffffffL %0x3fffffffL *30 \
  5.                   + (m)%0x3fffffffL /((m)%31+1)/31%31*5 + 4-12/((m)%31+3))
  6. #define UNSIGNED_BIT IMAX_BITS((unsigned)-1)
  7.  
  8. int main(void) {
  9. 	unsigned x = 4711;
  10.  
  11. 	unsigned mask = 1U << (UNSIGNED_BIT - 1); // most significant bit
  12. 	while (mask && !(x&mask)) mask >>= 1; // ignore leading zeros
  13. 	if (mask) // still bits to process ?
  14. 	{
  15. 		for (; mask; mask >>= 1)
  16. 		{
  17. 			// output '0' or '1'
  18. 			// !! normalizes the result of the bitwise and to 0 or 1
  19. 			putchar('0' + !!(x&mask));
  20. 		}
  21. 	}
  22. 	else putchar('0'); // if only 0 bits found, output 0
  23.  
  24. 	putchar('\n');
  25.  
  26. 	return 0;
  27. }
  28.  
Success #stdin #stdout 0s 9432KB
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stdin
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Standard input is empty
stdout
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1001001100111
https://ideone.com/eGtfSn
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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