charAt() returning weird values

Question

I am trying to make program that convert number to words but when I use charAt(0) to get the value of index 0 its returning me strange values

 import java.util.Scanner;

public class numToWord {
    public static   void main(String[] args) {

        String[] digit = {"Zero","One ","Two", "Three ","Four ","Five ","Six ", "Seven ", "Eight ", "Nine" };
        Scanner sc  = new Scanner(System.in);
        String strNum = sc.next(); //input 123
        int intnum = Integer.valueOf(strNum.charAt(0));
        System.out.println(intnum);
        System.out.println(digit[intnum]);
        //output 49

    }
}

example input 123 output 49

Input Output:

What exactly is strange? If you input the string `"5"`, it consists of a single character, `'5'`, which has a codepoint of 53 in most encodings. — Lasse V. Karlsen, Jul 11 '21 at 20:15
What do *you* think a `char` should contain? It contains the codepoint of a character (well, technically it could be just a surrogate pair, but that's the exception, for most commonly used characters `char` = codepoint holds true). — Joachim Sauer, Jul 11 '21 at 20:27
And after printing out the 'incorrect' value, the program will crash with an out-of-bounds array index, since there are not 54 elements in the digit array. (Oh, I didn't look at the linked picture of the output until now - yup, it crashed as expected). — iggy, Jul 11 '21 at 21:45

score 2 · Answer 1 · answered Jul 11 '21 at 20:29

You are currently reading the ascii value of the first character of your input. Also, you have spaces in your digit mapping. What you wanted to do was parse each digit and get the mapping. Something like,

String[] digit = { "Zero", "One", "Two", "Three", "Four", 
        "Five", "Six", "Seven", "Eight", "Nine" };
Scanner sc  = new Scanner(System.in);
String strNum = sc.next();
for (int i = 0; i < strNum.length(); i++) {
    if (i != 0) {
        System.out.print(" ");
    }
    int v = Character.digit(strNum.charAt(i), 10); // strNum.charAt(i) - '0'
    System.out.print(digit[v]);
}
System.out.println();

Seraj · Accepted Answer · 2021-07-12T09:42:38.890

valueOf() is used for string conversion not for char type.

If you want to convert a char value to an integer using valueOf() it's always return the ASCII value of it. Use Character.getNumericValue() to solve this problem.

import java.util.Scanner;
public class numToWord{
    public static   void main(String[] args) {
        String[] digit = {"Zero","One ","Two", "Three ","Four ","Five ","Six ", "Seven ", "Eight ", "Nine" };
        Scanner sc  = new Scanner(System.in);
        String strNum = sc.next();
        //int intnum = Integer.valueOf(strNum.charAt(0));
        int intnum = Character.getNumericValue(strNum.charAt(0));
        System.out.println(intnum);
        System.out.println(digit[intnum]);
    }
}

score 0 · Answer 3 · answered Jul 11 '21 at 20:56

0

Look up what ASCII is.

The character '1' maps to the decimal value 49 on the ASCII chart.

answered Jul 11 '21 at 20:56

Visual Studio

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charAt() returning weird values

3 Answers3