Created AnyBaseToDecimal.java

An algorithm which can convert a given number of any base to its decimal value

Conversions/AnyBaseToDecimal.java

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+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+
+/**
+ *
+ * @author Varun Upadhyay (https://github.com/varunu28)
+ *
+ */
+
+// Driver program
+public class AnyBaseToDecimal {
+    public static void main (String[] args) throws Exception{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        
+        String inp = br.readLine();
+        int base =  Integer.parseInt(br.readLine());
+
+        System.out.println("Input in base " + base + " is: " + inp);
+        System.out.println("Decimal value of " + inp + " is: " + convertToDecimal(inp, base));
+
+        br.close();
+    }
+
+    /**
+     * This method produces a decimal value of any given input number of any base
+     * @param inp_num String of which we need the decimal value and base in integer format
+     * @return string format of the decimal value
+     */
+
+    public static String convertToDecimal(String inp_num, int base) {
+        int len = inp_num.length();
+        int num = 0;
+        int pow = 1;
+
+        for (int i=len-1; i>=0; i--) {
+            if (valOfChar(inp_num.charAt(i)) >= base) {
+                return "Invalid Number";
+            }
+            num += valOfChar(inp_num.charAt(i))*pow;
+            pow *= base;
+        }
+        return String.valueOf(num);
+    }
+
+    /**
+     * This method produces integer value of the input character and returns it
+     * @param c Char of which we need the integer value of
+     * @return integer value of input char
+     */
+
+    public static int valOfChar(char c) {
+        if (c >= '0' && c <= '9') {
+            return (int)c - '0';
+        }
+        else {
+            return (int)c - 'A' + 10;
+        }
+    }
+}