CODEWITHSUNDEEP
java
Alexander Hsieh
Alexander Hsieh

Reputation: 11

Java addition giving wrong answer

I am trying to add four integers ie 4+3+2+1 but i get the value 202

class Task3{
public static void main (String args[]){
    String x=(args[0]);
    int I = Integer.parseInt (x);   
    char c1 = x.charAt(0);
    char c2 = x.charAt(1);
    char c3 = x.charAt(2);
    char c4 = x.charAt(3);
    System.out.println("First and last digit is: " + c1 +"," + c4);
    if (c1 > c4)
        System.out.println("The first digit is larger");
    else
        System.out.println("The second digit is larger");
    int sum = c1 + c2 + c3 + c4;
    System.out.println(sum);
}

}

Upvotes: 0

Views: 922

Answers (6)

tickle
tickle

Reputation: 1

I presume you are passing "4321" or similar to the program.

c1 will not be the number 1 but actually the Unicode number representing the character '1' which is actually 31 (in hexadecimal). The latest addition is adding these Unicode numbers.

See http://unicode-table.com/en/ for the list of unicode numbers to characters and also http://docs.oracle.com/javase/tutorial/i18n/text/unicode.html for more details of characters in Java.

Upvotes: 0

SparkOn
SparkOn

Reputation: 8946

The reason of the wrong output others already explained it now one of the way to get the correct output

int sum =0;
while(I>0){
    int rem = I%10;
    sum+=rem;
    I = I/10;
}
System.out.println(sum);

Upvotes: 1

tmarwen
tmarwen

Reputation: 16354

You are trying to sum up the chars ASCII codes and not the digit values. You have to retrieve the corresponding digit for each character and then evaluate you addition result:

class Task3
{
  public static void main (String args[])
  {
    String x=(args[0]);
    int I = Integer.parseInt (x);   
    char c1 = x.charAt(0);
    char c2 = x.charAt(1);
    char c3 = x.charAt(2);
    char c4 = x.charAt(3);
    int i1 = Character.digit(c1, 10);
    int i2 = Character.digit(c2, 10);
    int i3 = Character.digit(c3, 10);
    int i4 = Character.digit(c4, 10);
    System.out.println("First and last digit is: " + i1 +"," + i4);
    if (i1 > i4)
      System.out.println("The first digit is larger");
    else
      System.out.println("The second digit is larger");
    int sum = i1 + i2 + i3 + i4;
    System.out.println(sum);
  }

}

Upvotes: 2

Dr. Debasish Jana
Dr. Debasish Jana

Reputation: 7118

Change 

int sum = c1 + c2 + c3 + c4;

to 

int sum = c1 + c2 + c3 + c4 - 4 * '0';

Since c1, c2, c3, c4 are all characters, so a digit say. 4 is taken as '4' that is basically the ASCII value, so to get 4 and not '4' you need to subtract '0' from each of c1, c2, c3, c4, so 4 * '0' subtracted

Upvotes: 2

Lucas
Lucas

Reputation: 3281

replace char c1 = x.charAt(0); with Character.getNumericValue(x.charAt(0))

Upvotes: 2

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726539

This is because you are adding numeric values of UNICODE code points, not digits represented by the corresponding characters.

In order to get a digit from a character code, call Character.digit(c1, 10) (ten indicates that you want a decimal digit).

int c1 = Character.digit(x.charAt(0), 10);
int c2 = Character.digit(x.charAt(1), 10);
int c3 = Character.digit(x.charAt(2), 10);
int c4 = Character.digit(x.charAt(3), 10);

Upvotes: 2

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