In the "toInteger()" methode , why the output of k is always a random number ??? I don't understand

Question

import java.util.Scanner;

//your code goes here
public class Converter {
//Methode to convert a number to binary numbre
public static int toBinary(int x){
String binary="";
while(x > 0) {
binary = (x%2)+binary;
x /= 2;
}

return toInteger(binary) ;
}
//to convert String to Integer
public static int toInteger (String ch){
int k =0 ;
int a=1;
//System.out.println(ch.length());
for(int i=0 ; i<ch.length() ; i++){
k = k*a ;
k += ch.charAt(i) ;
a*=10;
}
return k ;
}
}

public class Program {
public static void main(String[ ] args) {
Scanner sc = new Scanner(System.in);
int x = sc.nextInt();
System.out.print(Converter.toBinary(x));
}
}

Answer 1

I think you need to modify a line inside your toInteger() method.

k += Integer.valueOf((String.valueOf(ch.charAt(i)))) ;

Because character are treated as integers internally so when you use ch.charAt(i) then it will take it's ASCII value and add to the value of 'k'.

Just an example
int a = 7 + '1';
// Output a = 56

Answer 2

As already mentioned above, ch.charAt(i); is returns a ASCII value there..
So convert to int digit by subtracting 48 and just do like this

for(int i=0 ;i<ch.length(); i++){
k = k*10 ;
k +=(ch.charAt(i)- 48);
//a*=10;
}

Answer 3

Jayakrishna🇮🇳 thank you , it worked

Answer 4

Avinesh you are right , ch.charAt return the code ASCII but when i wrote Integer.valueOf .... the output was "Cannot find Symbol"
What that's mean ?