decimal integer do a binary string

1. // Convert a decimal integer do a binary string
2. // added a test printf() you can remove later
3. // Turbo C modified for Pelles C vegaseat 19nov2004
4. /*
   author              :sailesh Kumar
   Website             :www.yongsters.co.cc
   Organisation        :saileshkumar.org
   
   */

5. #include <stdio.h>
7. void dec2bin(long decimal, char *binary);
9. int main()
10. {
11. long decimal;
12. char binary[80];
14. printf("\n\n Enter an integer value : ");
15. scanf("%ld",&decimal);
16. dec2bin(decimal,binary);
17. printf("\n The binary value of %ld is %s \n",decimal,binary);
19. getchar(); // trap enter
20. getchar(); // wait
21. return 0;
22. }
24. //
25. // accepts a decimal integer and returns a binary coded string
26. //
27. void dec2bin(long decimal, char *binary)
28. {
29. int k = 0, n = 0;
30. int neg_flag = 0;
31. int remain;
32. int old_decimal; // for test
33. char temp[80];
35. // take care of negative input
36. if (decimal < 0)
37. {
38. decimal = -decimal;
39. neg_flag = 1;
40. }
41. do
42. {
43. old_decimal = decimal; // for test
44. remain = decimal % 2;
45. // whittle down the decimal number
46. decimal = decimal / 2;
47. // this is a test to show the action
48. printf("%d/2 = %d remainder = %d\n", old_decimal, decimal, remain);
49. // converts digit 0 or 1 to character '0' or '1'
50. temp[k++] = remain + '0';
51. } while (decimal > 0);
53. if (neg_flag)
54. temp[k++] = '-'; // add - sign
55. else
56. temp[k++] = ' '; // space
58. // reverse the spelling
59. while (k >= 0)
60. binary[n++] = temp[--k];
62. binary[n-1] = 0; // end with NULL
63. }