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made this binart yo decimal converter and i want to make it smaller and more compact

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made this binart yo decimal converter and i want to make it smaller and more compact

 
-1
  #1
Jan 13th, 2009
hey,
i made this a few years ago. i want to take the error when u enter a different number and would like to make it more compact. can you guys help me make it smaller. this is a 8 bit binary to decimal converter.



c Syntax (Toggle Plain Text) 
  1.  
  2.       #include <stdio.h>
  3.       #include <string.h>
  4.  
  5.  
  6.  
  7.       int bin2dec(char *bin);
  8.  
  9.  
  10.  
  11.       int main()
  12.  
  13.       {
  14.  
  15.       char bin[9] = "";
  16.  
  17.       char *p;
  18.  
  19.       int dec;
  20.  
  21.  
  22.  
  23.       while(strcmp(bin,"0"))
  24.  
  25.       {
  26.  
  27.       printf("\n Enter a binary number (just 0 to EXIT): ");  //Enter number to be converted in binary form
  28.  
  29.       fgets(bin, sizeof(bin), stdin);
  30.  
  31.       // check for and remove trailing \n
  32.  
  33.       if ((p = strchr(bin,'\n')) != NULL)
  34.  
  35.       {
  36.  
  37.       *p = '\0'; 
  38.  
  39.      }
  40.  
  41.       dec = bin2dec(bin);
  42.  
  43.       if (dec) printf("\nDecimal = %d \n",dec); //Display Converted # in Decimal,
  44.  
  45.       }
  46.  
  47.  
  48.  
  49.       getchar(); // wait
  50.  
  51.       return 0;
  52.  
  53.       }
  54.  
  55.  
  56.  
  57.       // convert a binary string to a decimal number, returns decimal value
  58.  
  59.       int bin2dec(char *bin)
  60.  
  61.       {
  62.  
  63.       int b, k, m, n;
  64.  
  65.       int len, sum = 0;
  66.  
  67.  
  68.  
  69.       len = strlen(bin) - 1;
  70.  
  71.       for(k = 0; k <= len; k++)
  72.  
  73.       {
  74.  
  75.       n = (bin[k] - '0'); // char to numeric value
  76.  
  77.       if ((n > 1) || (n < 0))
  78.  
  79.       {
  80.  
  81.       puts("\n\n ERROR! BINARY has only 1 and 0!\n"); //Error if anything other than 1 or 0 entered
  82.  
  83.       return (0);
  84.  
  85.       }
  86.  
  87.       for(b = 1, m = len; m > k; m--)
  88.  
  89.       {
  90.  
  91.       // 1 2 4 8 16 32 64 128 ... place-values, reversed here
  92.  
  93.       b *= 2;	// 
  94.  
  95.       }
  96.  
  97.       // sum it up
  98.  
  99.       sum = sum + n * b;
  100.  
  101.       //printf("%d*%d + ",n,b); // uncomment to show the way this works
  102.  
  103.       }
  104.  
  105.       return(sum);
  106.  
  107.       }
Last edited by Ancient Dragon; Jan 13th, 2009 at 4:25 pm. Reason: add code tags
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Re: made this binart yo decimal converter and i want to make it smaller and more compact

 
0
  #2
Jan 13th, 2009
Instead of this:
c Syntax (Toggle Plain Text) 
  1. for(b = 1, m = len; m > k; m--)
  2. {
  3. // 1 2 4 8 16 32 64 128 ... place-values, reversed here
  4. b *= 2;
  5. }
  6. // sum it up
  7. sum = sum + n * b;

Include <math.h>
and replace your the previously mentioned code with this:
C Syntax (Toggle Plain Text) 
  1. sum += n * (int)pow(2, k);
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Re: made this binart yo decimal converter and i want to make it smaller and more compact

 
0
  #3
Jan 14th, 2009
> and replace your the previously mentioned code with this:
> sum += n * (int)pow(2, k);
Bad idea.
a) it's slower
b) you're at the mercy of whatever inaccuracies are inherent in the floating point library.

> can you guys help me make it smaller.
Sure
a) use code tags - something you're consistently failing to do
b) strip out the excess of newlines
c) learn to indent code.
It's horrible.
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Re: made this binart yo decimal converter and i want to make it smaller and more compact

 
0
  #4
Jan 14th, 2009
Well, if you're not afraid of pointers...

c Syntax (Toggle Plain Text) 
  1. int bin2dec(char * bin)
  2. {
  3.     int n;
  4.     int sum = 0;
  5.     while (*bin) 
  6.     {
  7.         n = *bin - '0';
  8.         if (n < 0 || n > 1)
  9.         {
  10.             printf("\nInvalid binary character: '%c'\n", *bin);
  11.             puts("Binary only uses the digits 0 and 1.\n");
  12.             return 0;
  13.         }
  14.         // double what we had before and add a new low bit
  15.         sum = (sum << 1) + n;
  16.         ++bin;
  17.     }
  18.     return sum;
  19. }

I'm really hoping this wasn't homework, you might be hard-pressed to explain where the idea came from
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