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AnyBaseToDecimal.java
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53 lines (48 loc) · 1.7 KB
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package Conversions;
/**
* @author Varun Upadhyay (https://github.com/varunu28)
*/
// Driver program
public class AnyBaseToDecimal {
public static void main(String[] args) {
assert convertToDecimal("1010", 2) == Integer.valueOf("1010", 2);
assert convertToDecimal("777", 8) == Integer.valueOf("777", 8);
assert convertToDecimal("999", 10) == Integer.valueOf("999", 10);
assert convertToDecimal("ABCDEF", 16) == Integer.valueOf("ABCDEF", 16);
assert convertToDecimal("XYZ", 36) == Integer.valueOf("XYZ", 36);
}
/**
* Convert any radix to decimal number
*
* @param s the string to be convert
* @param radix the radix
* @return decimal of bits
* @throws NumberFormatException if {@code bits} or {@code radix} is invalid
*/
public static int convertToDecimal(String s, int radix) {
int num = 0;
int pow = 1;
for (int i = s.length() - 1; i >= 0; i--) {
int digit = valOfChar(s.charAt(i));
if (digit >= radix) {
throw new NumberFormatException("For input string " + s);
}
num += valOfChar(s.charAt(i)) * pow;
pow *= radix;
}
return num;
}
/**
* Convert character to integer
*
* @param c the character
* @return represented digit of given character
* @throws NumberFormatException if {@code ch} is not UpperCase or Digit character.
*/
public static int valOfChar(char c) {
if (!(Character.isUpperCase(c) || Character.isDigit(c))) {
throw new NumberFormatException("invalid character :" + c);
}
return Character.isDigit(c) ? c - '0' : c - 'A' + 10;
}
}