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  1. #include <stdio.h>
  2.  
  3. unsigned int bits0(unsigned int num) {
  4. 	int count = 0; while(num) num >>=1, ++count; return count;	
  5. }
  6. //int ln2(int x) {return ln(x,8,1);} // 8 поставить sizeof/2 для универсальности
  7. int ln2(int x) {return ln1(x,8,1);} // 8 поставить sizeof/2 для универсальности
  8.  
  9. int ln(int x, int shift, int n) {
  10.     int y = x >> shift; 
  11.     if (y != 0) {x=y;n += shift;}
  12.     return (shift!=0) ? ln(x,shift>>1,n): n;
  13. }
  14. int ln1(int x, int shift, int n) {
  15.     int y = x >> shift; 
  16.     if (y != 0) {x=y;n += shift;}
  17.     return (shift!=2) ? ln(x,shift>>1,n): n+(x>>1);
  18. }
  19. int main(int argc, char **argv) {
  20. 	unsigned int j=1<<1,i=0;
  21. 	for (;i<15;++i,j<<=1){
  22. 	  unsigned int d = j|1;
  23. 	  printf("%lu==%lu\n", bits0(d), ln2(d));
  24. 	}
  25. //  return 0;	
  26. 	for (i=1;i<65536;++i)
  27. 		if(bits0(i)!=ln2(i))
  28. 	  		printf("ERROR i=%d %lu!=%lu\n", bits0(i), ln2(i));
  29.  
  30.   return 0;
  31. }
Success #stdin #stdout 0s 2248KB
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stdin
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Standard input is empty
stdout
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2==2
3==3
4==4
5==5
6==6
7==7
8==8
9==9
10==10
11==11
12==12
13==13
14==14
15==15
16==16
https://ideone.com/XsIR3q
language:
C (gcc 8.3)
created:
12 years ago
visibility:
secret

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