Binary to Base 10 decimal conversion

This is a discussion on Binary to Base 10 decimal conversion within the C Programming forums, part of the General Programming Boards category; Anyone know any good online converters? One that actually converts a binary decimal to base 10 decimal? Like 10101.001 -> ...

  1. #1
    Cogito Ergo Sum
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    Binary to Base 10 decimal conversion

    Anyone know any good online converters?

    One that actually converts a binary decimal to base 10 decimal?

    Like 10101.001 -> Base 10 decimal.

    All converters I have found online round up the numbers.

  2. #2
    Algorithm Dissector iMalc's Avatar
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    How about listing what you've already looked at so people wont suggest them again?
    What about the calculator program that comes with your OS?
    My homepage
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  3. #3
    Cogito Ergo Sum
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    It doesn't take in binary decimals like 10101.001

    No decimal places taken.

  4. #4
    Dr Dipshi++ mike_g's Avatar
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    Are you talking about fixed point representation?

    Floating point is a lot more common.
    Last edited by mike_g; 11-20-2007 at 12:14 AM.

  5. #5
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    It wouldn't be that hard to write your own code to do it.

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  6. #6
    Cogito Ergo Sum
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    I would easily write my code, if I could find out the method for doing it properly, then checking it. Otherwise I would get wrong answers if my method was wrong

  7. #7
    Kernel hacker
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    The method is that you start with the same algorithm as for binary string to ascii [you could in fact do it with strtol() for this part] up to the decimal dot. After the dot, each digit is half of the previous, with the first one after the dot being "worth" 0.5.

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  8. #8
    Cogito Ergo Sum
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    Well the main reason I was asking was because I have an exam tomorrow. And while I know how to do it, I was practicing some problems, but there were no answers, so I wanted to check my answers with some online converter.

    Writing a program would take a while :P

  9. #9
    Kernel hacker
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    Code:
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    
    int main()
    {
      for(;;) 
        {
          char input[100];
    
          char *p;
          double d = 0.0;
          double m = 0.5;
          int len;
          printf("Enter binary 'float' number (or 9 to exit):");
          if (fgets(input, sizeof(input), stdin) == NULL)
    	break;
          len = strlen(input);
          if (input[len-1]  == '\n') {
    	input[len-1] = 0;
          }
          else {
    	int ch;
    	printf("Error: input too long - ignored\n");
    	while((ch = getchar()) != '\n' && ch != EOF) ;
    	goto err;
          }
      
          p = input;
          if (*p == '9') {
    	break;
          }
          while(*p && *p != '.') {
    	if (*p < '0' || *p > '1') 
    	  {
    	    printf("Invalid input\n");
    	    goto err;
    	  }
    	d *= 2.0;
    	d += *p - '0';
    	p++;
          }
          if (*p) {
    	if (*p != '.') {
    	  printf("Expected a '.'\n");
    	  goto err;
    	}
    	p++;
    	while(*p) {
    	  if (*p < '0' || *p > '1') 
    	    {
    	      printf("Invalid input\n");
    	      goto err;
    	    }
    	  d += (*p - '0') * m;
    	  m *= 0.5;
    	  p++;
    	}
          }
          printf("Decimal: &#37;f\n", d);
        err:
          continue;
        }
      return 0;
    }
    How about that one - didn't take too long, did it?

    Edit: Appologies for short variable names and use of goto. If anyone would like to take the code and modify it to use longer names and no goto's, feel free.



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    Last edited by matsp; 11-20-2007 at 04:45 AM.
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  10. #10
    Cogito Ergo Sum
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    Pretty cool mats, I guess I'll use it =) but I won't modify it because it will take me a while to understand it lol.

    Thanks, did you actually type all that out?

  11. #11
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    Quote Originally Posted by JFonseka View Post
    Pretty cool mats, I guess I'll use it =) but I won't modify it because it will take me a while to understand it lol.

    Thanks, did you actually type all that out?
    Sure, it's only about 50 or so lines. Not that much - and a bit of copy'n'paste.

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    Compilers can produce warnings - make the compiler programmers happy: Use them!
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  12. #12
    Cogito Ergo Sum
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    To do that, it would take me several hours lol.

  13. #13
    Chinese pâté foxman's Avatar
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    Sorry for bringing up a somewhat "old" topic, but you could also have done this, ie:

    Code:
        10101.001
    =
        10101001 * 2^-3
    =       <convert to decimal, let's say with XP calculator>
        169 * 2^-3
    =
        169 / 2^3
    =
        169 / 8
    =
        21.125
    Tadam, by using only XP calculator (in scientific mode).

  14. #14
    Kernel hacker
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    Sure, that'll work.

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    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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