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  1. #include <stdio.h>
  2. #include <limits.h>
  3. #include <string.h>
  4.  
  5. int DivByShifting2(int n, unsigned shift)
  6. {
  7. unsigned un = n;
  8. unsigned sgn = 1 + ~(un >> ((sizeof(int) * CHAR_BIT) - 1));
  9. un = ((((un + sgn) ^ sgn) >> shift) + sgn) ^ sgn;
  10. memcpy(&n, &un, sizeof n);
  11. return n;
  12. }
  13.  
  14. int main(void)
  15. {
  16. int n, s;
  17. for (n = -10; n <= 10; n++)
  18. for (s = 0; s <= 4; s++)
  19. printf("%d / %d = %d\n", n, 1 << s, DivByShifting2(n, s));
  20. return 0;
  21. }
  22.  
Success #stdin #stdout 0s 1788KB
stdin
Standard input is empty
stdout
-10 / 1 = -10
-10 / 2 = -5
-10 / 4 = -2
-10 / 8 = -1
-10 / 16 = 0
-9 / 1 = -9
-9 / 2 = -4
-9 / 4 = -2
-9 / 8 = -1
-9 / 16 = 0
-8 / 1 = -8
-8 / 2 = -4
-8 / 4 = -2
-8 / 8 = -1
-8 / 16 = 0
-7 / 1 = -7
-7 / 2 = -3
-7 / 4 = -1
-7 / 8 = 0
-7 / 16 = 0
-6 / 1 = -6
-6 / 2 = -3
-6 / 4 = -1
-6 / 8 = 0
-6 / 16 = 0
-5 / 1 = -5
-5 / 2 = -2
-5 / 4 = -1
-5 / 8 = 0
-5 / 16 = 0
-4 / 1 = -4
-4 / 2 = -2
-4 / 4 = -1
-4 / 8 = 0
-4 / 16 = 0
-3 / 1 = -3
-3 / 2 = -1
-3 / 4 = 0
-3 / 8 = 0
-3 / 16 = 0
-2 / 1 = -2
-2 / 2 = -1
-2 / 4 = 0
-2 / 8 = 0
-2 / 16 = 0
-1 / 1 = -1
-1 / 2 = 0
-1 / 4 = 0
-1 / 8 = 0
-1 / 16 = 0
0 / 1 = 0
0 / 2 = 0
0 / 4 = 0
0 / 8 = 0
0 / 16 = 0
1 / 1 = 1
1 / 2 = 0
1 / 4 = 0
1 / 8 = 0
1 / 16 = 0
2 / 1 = 2
2 / 2 = 1
2 / 4 = 0
2 / 8 = 0
2 / 16 = 0
3 / 1 = 3
3 / 2 = 1
3 / 4 = 0
3 / 8 = 0
3 / 16 = 0
4 / 1 = 4
4 / 2 = 2
4 / 4 = 1
4 / 8 = 0
4 / 16 = 0
5 / 1 = 5
5 / 2 = 2
5 / 4 = 1
5 / 8 = 0
5 / 16 = 0
6 / 1 = 6
6 / 2 = 3
6 / 4 = 1
6 / 8 = 0
6 / 16 = 0
7 / 1 = 7
7 / 2 = 3
7 / 4 = 1
7 / 8 = 0
7 / 16 = 0
8 / 1 = 8
8 / 2 = 4
8 / 4 = 2
8 / 8 = 1
8 / 16 = 0
9 / 1 = 9
9 / 2 = 4
9 / 4 = 2
9 / 8 = 1
9 / 16 = 0
10 / 1 = 10
10 / 2 = 5
10 / 4 = 2
10 / 8 = 1
10 / 16 = 0