CareerCup

On questions like these, don't forget to handle cases where there is no binary equivalent.

public static String printBinary(String n) {
int intPart = Integer.parseInt(n.substring(0, n.indexOf(‘.’)));
double decPart = Double.parseDouble( n.substring(n.indexOf(‘.’), n.length()));
String int_string = “”;
while (intPart > 0) {
int r = intPart % 2;
intPart >>= 1;
int_string = r + int_string;
}
StringBuffer dec_string = new StringBuffer();
while (decPart > 0) {
if (dec_string.length() > 32) return “ERROR”;
if (decPart == 1) {
dec_string.append((int)decPart);
break;
}
double r = decPart * 2;
if (r >= 1) {
dec_string.append(1);
decPart = r - 1;
} else
{dec_string.append(0);
decPart = r;
}
}
return int_string + “.” + dec_string.toString();

//fraction part i have terminated to 10 digits

input=input.replaceAll("[^0-9.]+", "E");
		if(input.contains("E")||input.indexOf('.')!=input.lastIndexOf('.'))
			System.out.println("ERROR");
		else{
			int i = input.indexOf(".");
			int n = Integer.parseInt(input.substring(0, i));
			StringBuffer binary=new StringBuffer();
			while(n>0){
				int j = n%2;
				binary.append(j);
				n=n/2;
			}
			binary = binary.reverse();
			binary.append(".");
			double f = Double.parseDouble(input.substring(i));
			int count =0;
			while(f>0&&count<10){
				f=f*2;
				input=""+f;
				int p = input.indexOf(".");
				int a = Integer.parseInt(input.substring(0, i));
				f = Double.parseDouble(input.substring(p));
				binary.append(a);
				count++;
			}
			System.out.println(binary.toString());

Test cases:
Negative number.
Positive number.
Are white spaces allowed: " 123.45".

Here is my approach.
Note that i have not handled the case of negative numbers.

int binaryD(char *bin,int n,int depth)
{
        static int count;
 
        if(n)
        {
                count++;
                binaryD(bin,n/2,depth+1);
                bin[depth]=(n&1)?'1':'0';
        }
        return count;
}
 
int binaryF(char* bin,float f,int *depth)
{
        int count=0,i;
 
        if(f<=0.0f)
                return 1;
        if(f==1.0f)
        {
                bin[*depth]='1';
                return 1;
        }
        while(f)
        {
                f*=2;
                if(f==1.0f)
                {
                        bin[++*depth]='1';
                        return 1;
                }
                i=f;
                if(f>1.0f)
                {
                        bin[++*depth]='1';
                        f=f-i;
                }
                else
                        bin[++*depth]='0';
                if(++count>32)
                        return 0;
        }       
}       
 
void toBinary(char *s)
{
        int num=0,i,depth=0,po=10,count;
        char bin[50];
        float f=0.0f;
 
        for(i=0;s[i] && s[i]!='.';i++)
        {       
                if(s[i]>='0' && s[i]<='9')
                        num=num*10 + s[i]-'0';
                else
                        return;
        }
 
        if(s[i]=='.')
        {
                for(++i,po=10;s[i];i++,po*=10)
                        if(s[i]>='0' && s[i]<='9')
                                f=f+ (s[i]-'0')/(float)po;
                        else
                                return;
        }
 
        i=binaryD(bin,num,depth);
 
        for(count=i-1;count>=0;count--)
                printf("%c",bin[count]);
 
        count=i;
        if(f!=0.0f)
        {
                bin[i]='.';
                binaryF(bin,f,&i);
 
                for(;count<=i;count++)
                        printf("%c",bin[count]);
        }
}

ideone.com/GElaE

Please let me know if any corner cases are missing

i// made decimal point limited to 10

conversion(char binary[])
    float a;
   
    scanf("%f",&a);
    int int_part=(int)a,count=0,i=0;
    float frac=a-int_part;
    do{binary[i++]=a%2;}while((a/=)>0)
    binary[i++]='.';
    do{frac=frac*2;binary[i++]=(int)(frac);count++;}while(frac!=1.0f&&count<10);

public static void ConvertToBinary(string inputNumber)
        {
            string[] inputDigits = inputNumber.Split('.');
            List<string> outputBinaryDigits;
            bool IsValidInput = true;
            Console.WriteLine("The Decimal Number is {0}", inputNumber);
            if (inputDigits.Count() > 2)
            {
                Console.WriteLine("ERROR");
                IsValidInput = false;
            }
            else
            {
                outputBinaryDigits = new List<string>();
                int parseStatus = 0;

                foreach (string digit in inputDigits)
                {
                    int.TryParse(digit, out parseStatus);
                    if (parseStatus == 0)
                    {
                        Console.WriteLine("ERROR");
                        IsValidInput = false;
                        break;
                    }
                    else
                    {
                        outputBinaryDigits.Add(Convert.ToString(parseStatus, 2));
                    }
                }
                if (IsValidInput)
                {
                    Console.WriteLine("The Binary Equivalent is {0}", string.Join(".", outputBinaryDigits));
                }
            }
        }

Input : 125
Output:
The Decimal Number is 125
The Binary Equivalent is 1111101

Input: 125.10
Output:
The Decimal Number is 125.10
The Binary Equivalent is 1111101.1010

Input: 125.12.12
Output:
The Decimal Number is 125.12.12
ERROR

Input: 125.AD
Output:
The Decimal Number is 125.AD
ERROR