Error message!

[megan-smith]

hey there;
i wanted to write a program to convert binary to decimal.
i did that using the " character approach".
it works just fine.
then i decided to enhance the program by adding an error message whenever the input are invalid (i.e anything other than 0, 1 ), but i havent been able to figure it out yet.
i've been playing around with it but it is still not coming.
my knowledge of C program is very limited ( i've just started learning C).
was wondering if you guys could possibly help me with it.
any help is appreciated!

here is the codes of what i wrote:

#include <stdlib.h>
#include <stdio.h>

int main ()
{
    int decimalValue=0;
    int nextDigit;
    char binary;
    
    printf(" Enter Binary Number ! \n");
    binary = getchar();
    
    while (binary == '1' || binary == '0')
          {                 
               if (  binary == '1')
                    { 
                             nextDigit=1;           
                    }
                    
               else   
                     {                     
                             nextDigit=0;
                     }      
                                          
                            
                                  
              decimalValue = decimalValue*2 + nextDigit ; 
              binary = getchar();
                      
          }
          
    printf ("The Decimal Value= %i\n", decimalValue);
    
    system("PAUSE");
    return 0;
}

[WaltP]

hey there; i wanted to write a program to convert binary to decimal. i did that using the " character approach". it works just fine. then i decided to enhance the program by adding an error message whenever the input are invalid (i.e anything other than 0, 1 ), but i havent been able to figure it out yet. i've been playing around with it but it is still not coming.

I must be missing something because there seems to be no attempt in the posted code to deal with invalid input. We therefore can't tell what you are doing wrong.

[megan-smith]

here's the best i came up with.
but sitll, it doesn't account for invalid numbers which start with 0 or 1 ( ie 123)!
thanks in advance.

#include <stdlib.h>
#include <stdio.h>

int main ()
{
    int decimalValue=0;
    int nextDigit;
    char binary;

    
    printf("Enter Binary Number ! \n");
    binary = getchar();
    
    
    if (binary > '1' || binary < '0')
          {
              printf("ERROR!  \n");
          }
    else
          {
                    while (binary == '1' || binary == '0')
                          {                 
                                              if (  binary == '1')
                                                    { 
                                                              nextDigit=1;           
                                                    }
                    
                                              else   
                                                    {                     
                                                                nextDigit=0;
                                                    }      
                                          
                            
                                  
                              decimalValue = decimalValue*2 + nextDigit ; 
                              binary = getchar();
 
                                                   
                                                            
                                                   
                                               
                                                                    
                          }   
                        
                             
                                                              
                          
                  
                       printf ("The Decimal Value = %i\n", decimalValue);
                                                                                
            }
            
   
    
    system("PAUSE");
    return 0;
}

[Dave Sinkula]

Dave's short version: read all user input as the text it is; interpret it at your leisure.

[megan-smith]

Dave's short version: read all user input as the text it is; interpret it at your leisure.

but how?
I read the very first input.
but i'm stuck when it comes to the the second input and third and ....
it would have been great had you explained a bit more.
thanks though.
cheers

[Dave Sinkula]

Somewhere in section 3.
http://sinkula.homestead.com/files/posts.pdf

[Salem]

> but sitll, it doesn't account for invalid numbers which start with 0 or 1 ( ie 123)!
Maybe put the 'if' statement inside the 'while' loop ?

But separating input from conversion is good as well, as Dave has remarked.

[megan-smith]

putting if statement in the while loop didn't seem to work. at least the way i did it .
Could you please show on the codes what you meant.

how do you seperate the input form the conversion?
the link Dave gave out was way too high-level for me, which i did'nt really understand.
Could you be more explicit and clear.
I told ya.
I'm just beginning.

[Salem]

So post your latest effort, not a description of what you may have tried.