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  1. #define _CRT_SECURE_NO_WARNINGS
  2. #include <float.h>
  3. #include <math.h>
  4. #include <stdio.h>
  5.  
  6. #define max(a,b) (((a)>(b))?(a):(b))
  7.  
  8. void dispf(float f)
  9. {
  10. 	char		str[32];
  11. 	char*		pc;
  12. 	unsigned char*	pf;
  13. 	int		i, b;
  14.  
  15. 	pf = (unsigned char*)&f;
  16. 	pc = str;
  17. 	for (i = 0; i < 4; i++) {
  18. 		for (b = 0; b < 8; b++) {
  19. 			*pc++ = '0'+((pf[3-i]>>(7-b))&1);
  20. 		}
  21. 	}
  22. 	printf("%.1s %.8s %.23s\n", str, str + 1, str + 9);
  23. 	printf("%E\n", f);
  24. 	printf("%f\n", f);
  25. }
  26.  
  27. int main()
  28. {
  29. 	float	a, b, c, d;
  30.  
  31. 	printf("a = 1970.2\n");
  32. 	a = (float)1970.2;
  33. 	dispf(a);
  34. 	printf("a = 1970.199707\n");
  35. 	a = (float)1970.199707;
  36. 	dispf(a);
  37. 	printf("b = 1.970200E+03\n");
  38. 	sscanf("1.970200E+03", "%E", &b);
  39. 	dispf(b);
  40. 	printf("c = fabsf(a - b)\n");
  41. 	c = fabsf(a - b);
  42. 	dispf(c);
  43. 	printf("d = FLT_EPSILON\n");
  44. 	d = FLT_EPSILON;
  45. 	dispf(d);
  46. 	printf("d = max(fabsf(a), fabsf(b))\n");
  47. 	d = max(fabsf(a), fabsf(b));
  48. 	dispf(d);
  49. 	printf("d = FLT_EPSILON * max(fabsf(a), fabsf(b))\n");
  50. 	d = FLT_EPSILON * max(fabsf(a), fabsf(b));
  51. 	dispf(d);
  52. 	printf("%s\n", (c<=d)?"true":"false");
  53. 	return 0;
  54. }
  55.  
Success #stdin #stdout 0.01s 1720KB
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stdin
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Standard input is empty
stdout
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a = 1970.2
0 10001001 11101100100011001100110
1.970200E+03
1970.199951
a = 1970.199707
0 10001001 11101100100011001100100
1.970200E+03
1970.199707
b = 1.970200E+03
0 10001001 11101100100011001100110
1.970200E+03
1970.199951
c = fabsf(a - b)
0 01110011 00000000000000000000000
2.441406E-04
0.000244
d = FLT_EPSILON
0 01101000 00000000000000000000000
1.192093E-07
0.000000
d = max(fabsf(a), fabsf(b))
0 10001001 11101100100011001100110
1.970200E+03
1970.199951
d = FLT_EPSILON * max(fabsf(a), fabsf(b))
0 01110010 11101100100011001100110
2.348661E-04
0.000235
false
https://ideone.com/rU6G9
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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