Help with binary to decimal

[BentheMuffin]

I am trying to make a program that will change binary numbers to decimal, but it is not working and I am not sure why. It seems to be reversing the order of the input and therefore ignores 0s if it ends with one. I have the opposite of this working with the same square method, so I think it is just a problem with the conversion.

 

 

 

public void calc(int a) {

output1 = 0;

String input = String.valueOf(a);

String in[] = new String[input.length()];

for(int k = 0; k < input.length(); k++) {

in[k] = input.substring(k, k + 1);

}

for(int i = 0; i < input.length(); i++) {

if(in.equalsIgnoreCase("1")) {

int j = square(i, 2);

output1 = output1 + j;

}

}

label1.setText(Integer.toString(output1));

input1 = 0;

}

 

public int square(int a, int b) {

if(a == 0) return 1;

int total = b;

for(int i = 0; i < a - 1; i++) {

total = total * b;

}

return total;

}

 

[Guest]

For readability.

 

public void calc(int a) {  output1 = 0;  String input = String.valueOf(a);  String in[] = new String[input.length()];  for (int k = 0; k < input.length(); k++) {    in[k] = input.substring(k, k + 1);   }  for (int i = 0; i < input.length(); i++) {    if (in[i].equalsIgnoreCase("1")) {       output1 += square(i, 2);    }  }  label1.setText(Integer.toString(output1));  input1 = 0;}public int square(int a, int b) {  if (a == 0) return 1;  int total = b;                                                                      for (int i = 0; i < a - 1; i++) {    total *= b;  }  return total;}

[christianled59]

Sorry off topic but it made a smiley face with glasses. (I don't know decimal)

[Guest]

So I'm not entirely sure what language this is, I'm guessing C++?

 

Can you give some example inputs and the output that you are getting with the code as it is? I don't really understand why you are squaring anything as binary is based on a power-of-two system.

[BentheMuffin]

So I'm not entirely sure what language this is, I'm guessing C++?

 

Can you give some example inputs and the output that you are getting with the code as it is? I don't really understand why you are squaring anything as binary is based on a power-of-two system.

It is java, there is a tag at the top. 

If I out in 101 it does 5 correctly, but if I put in 110001 (49) It will return 35 which is 100011. I belive this is the cause for my other problem which is it ignores 0's at the begining or end, making it return 1 if I put in 100.

[Ciccioo]

the only problem is that the loop runs backwards

[Guest]

It is java, there is a tag at the top. 

If I out in 101 it does 5 correctly, but if I put in 110001 (49) It will return 35 which is 100011. I belive this is the cause for my other problem which is it ignores 0's at the begining or end, making it return 1 if I put in 100.

 

Ok. How's this:

public String binaryToDecimal(int binary) {  result = 0;  String binaryString = String.valueOf(binary);  for (int i = 0; i < binaryString.length(); i++) {    if (binaryString.charAt(i) == '1') {       result += pow(2, (binaryString.length() - 1) - i);    }  }  return Integer.toString(result);}

I think the problem is that you are going through the string from left to right, but the least significant bit is on the right.

[BentheMuffin]

Ok. How's this:

public String binaryToDecimal(int binary) {  result = 0;  String binaryString = String.valueOf(binary);  for (int i = 0; i < binaryString.length(); i++) {    if (binaryString.charAt(i) == '1') {       result += pow(2, (binaryString.length() - 1) - i);    }  }  return Integer.toString(result);}

I think the problem is that you are going through the string from left to right, but the least significant bit is on the right.

 

Your code helped me figure out what I did. I was using 2 for loops, leaving a lot more area for errors. I made your code fit into my program and it works fine now. Thanks