Data commit

Task/Non-decimal-radices-Convert/C-sharp/non-decimal-radices-convert.cs

@@ -0,0 +1,128 @@
+public static class BaseConverter {
+
+    /// <summary>
+    /// Converts a string to a number
+    /// </summary>
+    /// <returns>The number.</returns>
+    /// <param name="s">The string to convert.</param>
+    /// <param name="b">The base number (between 2 and 36).</param>
+    public static long stringToLong(string s, int b) {
+
+        if ( b < 2 || b > 36 )
+            throw new ArgumentException("Base must be between 2 and 36", "b");
+
+        checked {
+
+            int slen = s.Length;
+            long result = 0;
+            bool isNegative = false;
+
+            for ( int i = 0; i < slen; i++ ) {
+
+                char c = s[i];
+                int num;
+
+                if ( c == '-' ) {
+                    // Negative sign
+                    if ( i != 0 )
+                        throw new ArgumentException("A negative sign is allowed only as the first character of the string.", "s");
+
+                    isNegative = true;
+                    continue;
+                }
+
+                if ( c > 0x2F && c < 0x3A )
+                    // Numeric character (subtract from 0x30 ('0') to get numerical value)
+                    num = c - 0x30;
+                else if ( c > 0x40 && c < 0x5B )
+                    // Uppercase letter
+                    // Subtract from 0x41 ('A'), then add 10
+                    num = c - 0x37;  // 0x37 = 0x41 - 10
+                else if ( c > 0x60 && c < 0x7B )
+                    // Lowercase letter
+                    // Subtract from 0x61 ('a'), then add 10
+                    num = c - 0x57;  // 0x57 = 0x61 - 10
+                else
+                    throw new ArgumentException("The string contains an invalid character '" + c + "'", "s");
+
+                // Check that the digit is allowed by the base.
+
+                if ( num >= b )
+                    throw new ArgumentException("The string contains a character '" + c + "' which is not allowed in base " + b, "s");
+
+                // Multiply the result by the base, then add the next digit
+
+                result *= b;
+                result += num;
+
+            }
+
+            if ( isNegative )
+                result = -result;
+
+            return result;
+
+        }
+
+    }
+
+    /// <summary>
+    /// Converts a number to a string.
+    /// </summary>
+    /// <returns>The string.</returns>
+    /// <param name="n">The number to convert.</param>
+    /// <param name="b">The base number (between 2 and 36).</param>
+    public static string longToString(long n, int b) {
+
+        // This uses StringBuilder, so it only works with .NET 4.0 or higher. For earlier versions, the StringBuilder
+        // can be replaced with simple string concatenation.
+
+        if ( b < 2 || b > 36 )
+            throw new ArgumentException("Base must be between 2 and 36", "b");
+
+        // If the base is 10, call ToString() directly, which returns a base-10 string.
+
+        if ( b == 10 )
+            return n.ToString();
+
+        checked {
+            long longBase = b;
+
+            StringBuilder sb = new StringBuilder();
+
+            if ( n < 0 ) {
+                // Negative numbers
+                n = -n;
+                sb.Append('-');
+            }
+
+            long div = 1;
+            while ( n / div >= b )
+                // Continue multiplying the dividend by the base until it reaches the greatest power of
+                // the base which is less than or equal to the number.
+                div *= b;
+
+            while ( true ) {
+                byte digit = (byte) (n / div);
+
+                if ( digit < 10 )
+                    // Numeric character (0x30 = '0')
+                    sb.Append((char) (digit + 0x30));
+                else
+                    // Alphabetic character (for digits > 10) (0x61 = 'a')
+                    sb.Append((char) (digit + 0x57));  // 0x61 - 10
+
+                if ( div == 1 )
+                    // Stop when the dividend reaches 1
+                    break;
+
+                n %= div;
+                div /= b;
+            }
+
+            return sb.ToString();
+        }
+
+    }
+
+}