Need help converting from ASCII to binary

Question

I'm very new to C, so I don't know much about it. Pointers are something I still haven't learned... I need to show a single character in decimal and binary. In decimals its easy but I can't get it to binary in any way... I get the ASCII number and compare it's module with 2 but it shows a really awkward number... what is wrong with the code?(It's in portuguese This is my code:

#include <stdio.h>
#include <conio.c> //library my professor created to assist his students
#include <string.h>
#define MAXIMO 8

int main( void )
{
  char caracter;
  int aux, resto[MAXIMO], contador, decimal, numero;
  printf( "Digite um UNICO caracter: " );
  caracter = getch();
  numero = caracter;
  decimal = caracter;
  aux = 0;
  do
  {
    if (numero % 2 == 0)
    {
      resto[aux] = 0;
    }
    else
    {
      resto[aux] = 1;
    }
    numero = numero / 2;
    aux++;

  }
  while (numero >= '0');
  //system("cls");
  printf( "\n\n%d\n\n", aux );
  printf( "\nCaracter em Binario: " );
  for (contador = aux; contador >= 0; contador--)
  {
    printf( "%d", resto[contador] );
  }
  printf( "\nValor decimal do caracter: %d", decimal );
  getch();
  return 0;
}

somethings I use like getch(); and return 0; in the end are just so my teacher don't kill me... I don't fully know why it's there but it has to be.

For starters: contador = aux needs to be contador = aux-1; as aux is one past the last index that was set in the while loop above that. — kaylum
– kaylum, Commented Oct 12, 2016 at 20:05
while(numero >= '0'); is also wrong. '0' and 0 are different values. You want the latter. — kaylum
– kaylum, Commented Oct 12, 2016 at 20:09
@kaylum if I use contador = aux-1 it only prints 7 numbers and doesn't fill the last one with a 0, that's why I used aux. I saw this '0' error too, thanks. — Vinícius Breda
– Vinícius Breda, Commented Oct 12, 2016 at 20:12
About your last sentence: the getch(); is there so that if the console output is to a popup window it won't just disappear before you can read any output. The return 0; is there because the function type is int (although main is an exception, it is not mandatory in this case to return a value). — Weather Vane
– Weather Vane, Commented Oct 12, 2016 at 20:35

granmirupa · Accepted Answer · 2016-10-12 20:50:41Z

1

Your code had some errors in the while condition:

#include <stdio.h>
#include <string.h>
#define MAXIMO 8

int main( void )
{
  char caracter;
  int aux, resto[MAXIMO], contador, decimal, numero;
  printf( "Digite um UNICO caracter: " );
  caracter = getchar(); // I used getchar instead of getch()
  numero = caracter;
  decimal = caracter;
  aux = 0;
  do
  {
    if (numero % 2 == 0)
    {
      resto[aux] = 0;
    }
    else
    {
      resto[aux] = 1;
    }
    numero = numero / 2;
    aux++;

  }
  while (numero > 0); // > than 0 not >= '0' 
  //system("cls");
  printf( "\n\n%d\n\n", aux );
  printf( "\nCaracter em Binario: " );
  for (contador = aux-1; contador >= 0; contador--) //aux-1
  {
    printf( "%d", resto[contador] );
  }
  printf( "\nValor decimal do caracter: %d", decimal );
  getchar();
  return 0;
}

N.B.

'0' and 0 are differents
> (greater) and >= (greater or equal) have different meaning

edited Oct 12, 2016 at 20:50

answered Oct 12, 2016 at 20:16

granmirupa

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2 Comments

Vinícius Breda Over a year ago

I've made some changes to my code in which using 7 instead of aux or aux-1 solves the problem of numbers only showing 7 characters I had before. I used getch because I want only one character leaving no room for user mistakes, if I use any other function it lets the user enter more and I'll have to validate the answer.

granmirupa Over a year ago

@ViníciusBreda you can use getch() if you want, but is not a function of standard c. It's in a library made for windows os.

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