Java Programs›Basics & I/O›Convert char to int

Convert char to int in Java

beginner· Basics & I/O · Type Conversion

Problem

A Java char is stored as a 16-bit number (its character code), so converting it to int gives that code — 'A' is 65 and the digit '7' is 55, not 7.

Given the characters 'A' and '7', print their character codes and the numeric value of the digit '7'.

Input

'A', '7'

Output

65, 55, 7

Java Program

Java

public class CharToInt {
    public static void main(String[] args) {
        char letter = 'A';
        char digit = '7';

        int code = letter;          // widening: a char already is a number (its character code)
        int digitCode = digit;      // the code of the symbol '7', not the value 7
        int digitValue = digit - '0'; // distance from '0' gives the actual digit

        System.out.println("Code of 'A': " + code);
        System.out.println("Code of '7': " + digitCode);
        System.out.println("Value of '7': " + digitValue);
    }
}

▶ Run Code

Output

Code of 'A': 65
Code of '7': 55
Value of '7': 7

Core Logic

Assigning a char to an int gives its character code; subtracting '0' gives a digit's actual value, because the digits 0 to 9 have consecutive codes.

How It Works

1int code = letter; is a widening conversion, so no cast is needed; 'A' becomes 65.
2int digitCode = digit; stores the code of the symbol '7', which is 55.
3digit - '0' computes 55 − 48 = 7, the value the digit represents.
4Each result is printed on its own line.

'9' - '0' is 57 − 48 = 9, and '0' - '0' is 0, so the trick works for every digit.

💡

Key Point: Mixing up the two meanings is a common bug: summing the digits of "123" with (int) c gives 150 (49 + 50 + 51) instead of 6.

Key Concepts

widening conversioncharacter codeschar arithmetic

Approach 2: Using Character.getNumericValue()

Java

public class CharToIntGetNumericValue {
    public static void main(String[] args) {
        char[] samples = {'7', 'b', 'Z', '#'};

        for (char c : samples) {
            int value = Character.getNumericValue(c); // letters count as 10 to 35, -1 means no value
            System.out.println("'" + c + "' -> " + value);
        }

        System.out.println("Character.digit('b', 16) -> " + Character.digit('b', 16)); // value in a given base
    }
}

▶ Run Code

Output

'7' -> 7
'b' -> 11
'Z' -> 35
'#' -> -1
Character.digit('b', 16) -> 11

Core Logic

Character.getNumericValue returns a character's value as a digit and extends it to letters, which count as 10 to 35 — useful for bases above 10.

How It Works

1'7' gives 7, the same as '7' - '0'.
2'b' gives 11 and 'Z' gives 35, in either case.
3Characters with no numeric value, like '#', give -1.
4Character.digit(c, radix) limits the answer to one base, returning -1 if the digit is invalid there.