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Task/Non-decimal-radices-Convert/Nim/non-decimal-radices-convert.nim

@@ -0,0 +1,33 @@
+import strutils
+
+proc reverse(a: string): string =
+  result = newString(a.len)
+  for i, c in a:
+    result[a.high - i] = c
+
+const digits = "0123456789abcdefghijklmnopqrstuvwxyz"
+
+proc toBase[T](num: T, base: range[2..36]): string =
+  if num == 0: return "0"
+  result = ""
+  if num < 0: result.add '-'
+  var tmp = abs(num)
+  var s = ""
+  while tmp > 0:
+    s.add digits[int(tmp mod base)]
+    tmp = tmp div base
+  result.add s.reverse
+
+proc fromBase(str: string, base: range[2..36]): BiggestInt =
+  var str = str
+  let first = if str[0] == '-': 1 else: 0
+
+  for i in first .. str.high:
+    let c = str[i].toLower
+    assert c in digits[0 .. <base]
+    result = result * base + digits.find c
+
+  if first == 1: result *= -1
+
+echo 26.toBase 16
+echo "1a".fromBase 16