From e54726df8e751302fe921c6df2af6d8e6f4d83be Mon Sep 17 00:00:00 2001
From: Stephane Janel <stephane.janel@amadeus.com>
Date: Tue, 7 May 2024 00:25:45 +0200
Subject: [PATCH] Split mathhelpers.hpp into dedicated include files for each
 functionality

---
 src/api/exchanges/src/bithumbprivateapi.cpp   |   3 +-
 src/http-request/src/besturlpicker.cpp        |   2 +-
 src/objects/include/monetaryamount.hpp        |   3 +-
 src/objects/src/monetaryamount.cpp            |   3 +-
 src/objects/test/monetaryamount_test.cpp      |   2 +-
 src/tech/CMakeLists.txt                       |   9 +-
 src/tech/include/ipow.hpp                     | 104 +++++++++++
 .../include/levenshteindistancecalculator.hpp |   4 +-
 src/tech/include/mathhelpers.hpp              | 175 ------------------
 src/tech/include/nchars.hpp                   |  15 ++
 src/tech/include/ndigits.hpp                  |  99 ++++++++++
 src/tech/include/overflow-check.hpp           |   1 -
 .../include/static_string_view_helpers.hpp    |   2 +-
 src/tech/include/stringhelpers.hpp            |   3 +-
 src/tech/include/timedef.hpp                  |   1 +
 src/tech/include/timestring.hpp               |   1 +
 src/tech/include/toupperlower.hpp             |   1 +
 src/tech/include/url-encode.hpp               |   1 -
 src/tech/src/simpletable.cpp                  |   3 +-
 src/tech/test/ipow_test.cpp                   |  28 +++
 ...{mathhelpers_test.cpp => ndigits_test.cpp} |  31 ++--
 21 files changed, 281 insertions(+), 210 deletions(-)
 create mode 100644 src/tech/include/ipow.hpp
 delete mode 100644 src/tech/include/mathhelpers.hpp
 create mode 100644 src/tech/include/nchars.hpp
 create mode 100644 src/tech/include/ndigits.hpp
 create mode 100644 src/tech/test/ipow_test.cpp
 rename src/tech/test/{mathhelpers_test.cpp => ndigits_test.cpp} (92%)

diff --git a/src/api/exchanges/src/bithumbprivateapi.cpp b/src/api/exchanges/src/bithumbprivateapi.cpp
index 356d5108..8446e0e4 100644
--- a/src/api/exchanges/src/bithumbprivateapi.cpp
+++ b/src/api/exchanges/src/bithumbprivateapi.cpp
@@ -42,9 +42,10 @@
 #include "exchangepublicapitypes.hpp"
 #include "file.hpp"
 #include "httprequesttype.hpp"
+#include "ipow.hpp"
 #include "market.hpp"
-#include "mathhelpers.hpp"
 #include "monetaryamount.hpp"
+#include "ndigits.hpp"
 #include "opened-order.hpp"
 #include "orderid.hpp"
 #include "ordersconstraints.hpp"
diff --git a/src/http-request/src/besturlpicker.cpp b/src/http-request/src/besturlpicker.cpp
index 79616efd..3891361d 100644
--- a/src/http-request/src/besturlpicker.cpp
+++ b/src/http-request/src/besturlpicker.cpp
@@ -9,7 +9,7 @@
 #include <string_view>
 
 #include "cct_log.hpp"
-#include "mathhelpers.hpp"
+#include "ipow.hpp"
 
 namespace cct {
 BestURLPicker::BestURLPicker(std::span<const std::string_view> baseUrls)
diff --git a/src/objects/include/monetaryamount.hpp b/src/objects/include/monetaryamount.hpp
index c1161dca..6df78f2a 100644
--- a/src/objects/include/monetaryamount.hpp
+++ b/src/objects/include/monetaryamount.hpp
@@ -15,7 +15,8 @@
 #include "cct_log.hpp"
 #include "cct_string.hpp"
 #include "currencycode.hpp"
-#include "mathhelpers.hpp"
+#include "ipow.hpp"
+#include "ndigits.hpp"
 
 namespace cct {
 
diff --git a/src/objects/src/monetaryamount.cpp b/src/objects/src/monetaryamount.cpp
index 75de8a25..43bff178 100644
--- a/src/objects/src/monetaryamount.cpp
+++ b/src/objects/src/monetaryamount.cpp
@@ -23,7 +23,8 @@
 #include "cct_exception.hpp"
 #include "cct_invalid_argument_exception.hpp"
 #include "currencycode.hpp"
-#include "mathhelpers.hpp"
+#include "ipow.hpp"
+#include "ndigits.hpp"
 #include "stringhelpers.hpp"
 
 namespace cct {
diff --git a/src/objects/test/monetaryamount_test.cpp b/src/objects/test/monetaryamount_test.cpp
index ec330c50..6a82fa0c 100644
--- a/src/objects/test/monetaryamount_test.cpp
+++ b/src/objects/test/monetaryamount_test.cpp
@@ -9,7 +9,7 @@
 #include "cct_invalid_argument_exception.hpp"
 #include "cct_string.hpp"
 #include "currencycode.hpp"
-#include "mathhelpers.hpp"
+#include "ipow.hpp"
 
 namespace cct {
 
diff --git a/src/tech/CMakeLists.txt b/src/tech/CMakeLists.txt
index 6f53cb61..5f8240ae 100644
--- a/src/tech/CMakeLists.txt
+++ b/src/tech/CMakeLists.txt
@@ -91,8 +91,13 @@ else()
 endif()
 
 add_unit_test(
-    mathhelpers_test
-    test/mathhelpers_test.cpp
+    ndigits_test
+    test/ndigits_test.cpp
+)
+
+add_unit_test(
+    ipow_test
+    test/ipow_test.cpp
 )
 
 add_unit_test(
diff --git a/src/tech/include/ipow.hpp b/src/tech/include/ipow.hpp
new file mode 100644
index 00000000..ff016fa6
--- /dev/null
+++ b/src/tech/include/ipow.hpp
@@ -0,0 +1,104 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+#include <limits>
+
+namespace cct {
+/// constexpr and integral version of math.power.
+/// Taken from https://gist.github.com/orlp/3551590
+constexpr int64_t ipow(int64_t base, uint8_t exp) noexcept {
+  constexpr uint8_t highest_bit_set[] = {0,   1,   2,   2,   3,   3,   3,   3,   4,   4,   4,   4,   4,   4,   4,
+                                         4,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,
+                                         5,   5,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,
+                                         6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,
+                                         6,   6,   6,   255,  // anything past 63 is a guaranteed overflow with base > 1
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
+
+  int64_t result = 1;
+
+  switch (highest_bit_set[exp]) {
+    case 255:  // we use 255 as an overflow marker and return 0 on overflow/underflow
+      return base == 1 ? 1 : (base == -1 ? (1 - 2 * (exp & 1)) : 0);
+    case 6:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      exp >>= 1;
+      base *= base;
+      [[fallthrough]];
+    case 5:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      exp >>= 1;
+      base *= base;
+      [[fallthrough]];
+    case 4:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      exp >>= 1;
+      base *= base;
+      [[fallthrough]];
+    case 3:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      exp >>= 1;
+      base *= base;
+      [[fallthrough]];
+    case 2:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      exp >>= 1;
+      base *= base;
+      [[fallthrough]];
+    case 1:
+      if ((exp & 1U) != 0) {
+        result *= base;
+      }
+      [[fallthrough]];
+    default:
+      return result;
+  }
+}
+
+/// Optimization of ipow(10, uint8_t exp)
+constexpr int64_t ipow10(uint8_t exp) noexcept {
+  constexpr const int64_t kPow10Table[] = {1LL,
+                                           10LL,
+                                           100LL,
+                                           1000LL,
+                                           10000LL,
+                                           100000LL,
+                                           1000000LL,
+                                           10000000LL,
+                                           100000000LL,
+                                           1000000000LL,
+                                           10000000000LL,
+                                           100000000000LL,
+                                           1000000000000LL,
+                                           10000000000000LL,
+                                           100000000000000LL,
+                                           1000000000000000LL,
+                                           10000000000000000LL,
+                                           100000000000000000LL,
+                                           1000000000000000000LL};
+  return exp < sizeof(kPow10Table) / sizeof(kPow10Table[0]) ? kPow10Table[exp] : std::numeric_limits<int64_t>::max();
+}
+
+}  // namespace cct
\ No newline at end of file
diff --git a/src/tech/include/levenshteindistancecalculator.hpp b/src/tech/include/levenshteindistancecalculator.hpp
index 05844e3f..bbd3ca87 100644
--- a/src/tech/include/levenshteindistancecalculator.hpp
+++ b/src/tech/include/levenshteindistancecalculator.hpp
@@ -5,10 +5,9 @@
 #include "cct_vector.hpp"
 
 namespace cct {
+
 class LevenshteinDistanceCalculator {
  public:
-  LevenshteinDistanceCalculator() noexcept = default;
-
   /// Computes the levenshtein distance between both input words.
   /// Complexity is in 'word1.length() * word2.length()' in time,
   /// min(word1.length(), word2.length()) in space.
@@ -18,4 +17,5 @@ class LevenshteinDistanceCalculator {
   // This is only for caching purposes, so that repeated calls to distance calculation do not allocate memory each time
   vector<int> _minDistance;
 };
+
 }  // namespace cct
\ No newline at end of file
diff --git a/src/tech/include/mathhelpers.hpp b/src/tech/include/mathhelpers.hpp
deleted file mode 100644
index ee934187..00000000
--- a/src/tech/include/mathhelpers.hpp
+++ /dev/null
@@ -1,175 +0,0 @@
-#pragma once
-
-#include <array>
-#include <concepts>
-#include <cstdint>
-#include <limits>
-#include <type_traits>
-
-namespace cct {
-/// constexpr and integral version of math.power.
-/// Taken from https://gist.github.com/orlp/3551590
-constexpr int64_t ipow(int64_t base, uint8_t exp) noexcept {
-  constexpr uint8_t highest_bit_set[] = {0,   1,   2,   2,   3,   3,   3,   3,   4,   4,   4,   4,   4,   4,   4,
-                                         4,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,   5,
-                                         5,   5,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,
-                                         6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,   6,
-                                         6,   6,   6,   255,  // anything past 63 is a guaranteed overflow with base > 1
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
-                                         255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
-
-  int64_t result = 1;
-
-  switch (highest_bit_set[exp]) {
-    case 255:  // we use 255 as an overflow marker and return 0 on overflow/underflow
-      return base == 1 ? 1 : (base == -1 ? (1 - 2 * (exp & 1)) : 0);
-    case 6:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      exp >>= 1;
-      base *= base;
-      [[fallthrough]];
-    case 5:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      exp >>= 1;
-      base *= base;
-      [[fallthrough]];
-    case 4:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      exp >>= 1;
-      base *= base;
-      [[fallthrough]];
-    case 3:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      exp >>= 1;
-      base *= base;
-      [[fallthrough]];
-    case 2:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      exp >>= 1;
-      base *= base;
-      [[fallthrough]];
-    case 1:
-      if ((exp & 1U) != 0) {
-        result *= base;
-      }
-      [[fallthrough]];
-    default:
-      return result;
-  }
-}
-
-/// Optimization of ipow(10, uint8_t exp)
-constexpr int64_t ipow10(uint8_t exp) noexcept {
-  constexpr const int64_t kPow10Table[] = {1LL,
-                                           10LL,
-                                           100LL,
-                                           1000LL,
-                                           10000LL,
-                                           100000LL,
-                                           1000000LL,
-                                           10000000LL,
-                                           100000000LL,
-                                           1000000000LL,
-                                           10000000000LL,
-                                           100000000000LL,
-                                           1000000000000LL,
-                                           10000000000000LL,
-                                           100000000000000LL,
-                                           1000000000000000LL,
-                                           10000000000000000LL,
-                                           100000000000000000LL,
-                                           1000000000000000000LL};
-  return exp < std::size(kPow10Table) ? kPow10Table[exp] : std::numeric_limits<int64_t>::max();
-}
-
-/// Return the number of digits of given integral.
-/// The minus sign is not counted.
-/// Uses dichotomy for highest performance as possible.
-constexpr int ndigits(std::signed_integral auto n) noexcept {
-  using T = decltype(n);
-  if constexpr (std::is_same_v<T, int8_t>) {
-    return n < 0 ? (n > -100 ? (n > -10 ? 1 : 2) : 3) : (n < 100 ? (n < 10 ? 1 : 2) : 3);
-  } else if constexpr (std::is_same_v<T, int16_t>) {
-    return n < 0 ? (n > -1000 ? (n > -100 ? (n > -10 ? 1 : 2) : 3) : (n > -10000 ? 4 : 5))
-                 : (n < 1000 ? (n < 100 ? (n < 10 ? 1 : 2) : 3) : (n < 10000 ? 4 : 5));
-  } else if constexpr (std::is_same_v<T, int32_t>) {
-    return n < 0 ? (n > -1000000
-                        ? (n > -1000 ? (n > -100 ? (n > -10 ? 1 : 2) : 3) : (n > -100000 ? (n > -10000 ? 4 : 5) : 6))
-                        : (n > -100000000 ? (n > -10000000 ? 7 : 8) : (n > -1000000000 ? 9 : 10)))
-                 : (n < 1000000 ? (n < 1000 ? (n < 100 ? (n < 10 ? 1 : 2) : 3) : (n < 100000 ? (n < 10000 ? 4 : 5) : 6))
-                                : (n < 100000000 ? (n < 10000000 ? 7 : 8) : (n < 1000000000 ? 9 : 10)));
-  } else {
-    // int64_t
-    return n < 0 ? (n > -10000000000L
-                        ? (n > -1000000L ? (n > -1000L ? (n > -100L ? (n > -10L ? 1 : 2) : 3)
-                                                       : (n > -100000L ? (n > -10000L ? 4 : 5) : 6))
-                                         : (n > -100000000L ? (n > -10000000L ? 7 : 8) : (n > -1000000000L ? 9 : 10)))
-                        : (n > -10000000000000000L
-                               ? (n > -10000000000000L
-                                      ? (n > -1000000000000L ? (n > -100000000000L ? 11 : 12) : 13)
-                                      : (n > -1000000000000000L ? (n > -100000000000000L ? 14 : 15) : 16))
-                               : (n > -1000000000000000000L ? (n > -100000000000000000L ? 17 : 18) : 19)))
-                 : (n < 10000000000L
-                        ? (n < 1000000L ? (n < 1000L ? (n < 100L ? (n < 10L ? 1 : 2) : 3)
-                                                     : (n < 100000L ? (n < 10000L ? 4 : 5) : 6))
-                                        : (n < 100000000L ? (n < 10000000L ? 7 : 8) : (n < 1000000000L ? 9 : 10)))
-                        : (n < 10000000000000000L
-                               ? (n < 10000000000000L ? (n < 1000000000000L ? (n < 100000000000L ? 11 : 12) : 13)
-                                                      : (n < 1000000000000000L ? (n < 100000000000000L ? 14 : 15) : 16))
-                               : (n < 1000000000000000000L ? (n < 100000000000000000L ? 17 : 18) : 19)));
-  }
-}
-
-/// Count the number of digits including the possible minus sign for negative integrals.
-constexpr int nchars(std::signed_integral auto n) noexcept { return ndigits(n) + static_cast<int>(n < 0); }
-
-/// Return the number of digits of given integral.
-/// Uses dichotomy for highest performance as possible.
-constexpr int ndigits(std::unsigned_integral auto n) noexcept {
-  using T = decltype(n);
-  if constexpr (std::is_same_v<T, uint8_t>) {
-    return n < 100U ? (n < 10U ? 1 : 2) : 3;
-  } else if constexpr (std::is_same_v<T, uint16_t>) {
-    return n < 1000U ? (n < 100U ? (n < 10U ? 1 : 2) : 3) : (n < 10000U ? 4 : 5);
-  } else if constexpr (std::is_same_v<T, uint32_t>) {
-    return n < 1000000U ? (n < 1000U ? (n < 100U ? (n < 10U ? 1 : 2) : 3) : (n < 100000U ? (n < 10000U ? 4 : 5) : 6))
-                        : (n < 100000000U ? (n < 10000000U ? 7 : 8) : (n < 1000000000U ? 9 : 10));
-  } else {
-    // uint64_t
-    return n < 10000000000UL
-               ? (n < 1000000UL
-                      ? (n < 1000UL ? (n < 100UL ? (n < 10UL ? 1 : 2) : 3) : (n < 100000UL ? (n < 10000UL ? 4 : 5) : 6))
-                      : (n < 100000000UL ? (n < 10000000UL ? 7 : 8) : (n < 1000000000UL ? 9 : 10)))
-               : (n < 10000000000000000UL
-                      ? (n < 10000000000000UL ? (n < 1000000000000UL ? (n < 100000000000UL ? 11 : 12) : 13)
-                                              : (n < 1000000000000000UL ? (n < 100000000000000UL ? 14 : 15) : 16))
-                      : (n < 1000000000000000000UL ? (n < 100000000000000000UL ? 17 : 18)
-                                                   : (n < 10000000000000000000UL ? 19 : 20)));
-  }
-}
-
-/// Synonym of ndigits for unsigned types.
-constexpr int nchars(std::unsigned_integral auto n) noexcept { return ndigits(n); }
-
-}  // namespace cct
\ No newline at end of file
diff --git a/src/tech/include/nchars.hpp b/src/tech/include/nchars.hpp
new file mode 100644
index 00000000..88f3c4dd
--- /dev/null
+++ b/src/tech/include/nchars.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <concepts>
+
+#include "ndigits.hpp"
+
+namespace cct {
+
+/// Count the number of digits including the possible minus sign for negative integrals.
+constexpr int nchars(std::signed_integral auto n) noexcept { return ndigits(n) + static_cast<int>(n < 0); }
+
+/// Synonym of ndigits for unsigned types.
+constexpr int nchars(std::unsigned_integral auto n) noexcept { return ndigits(n); }
+
+}  // namespace cct
\ No newline at end of file
diff --git a/src/tech/include/ndigits.hpp b/src/tech/include/ndigits.hpp
new file mode 100644
index 00000000..c2edf668
--- /dev/null
+++ b/src/tech/include/ndigits.hpp
@@ -0,0 +1,99 @@
+#pragma once
+
+#include <concepts>
+#include <cstdint>
+#include <limits>
+
+namespace cct {
+
+/// Return the number of digits of given integral.
+/// The minus sign is not counted - use nchars if you want it counted.
+/// Maximum of int(log2(std::numeric_limits<T>::digits10)) + 2 comparisons.
+constexpr int ndigits(std::signed_integral auto n) noexcept {
+  using T = decltype(n);
+
+  if constexpr (std::numeric_limits<T>::digits10 == 2) {
+    return n < 0 ? (n > -10 ? 1 : (n > -100 ? 2 : 3)) : n < 10 ? 1 : (n < 100 ? 2 : 3);
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 4) {
+    return n < 0 ? (n > -100 ? (n > -10 ? 1 : 2) : (n > -1000 ? 3 : (n > -10000 ? 4 : 5)))
+                 : (n < 100 ? (n < 10 ? 1 : 2) : (n < 1000 ? 3 : (n < 10000 ? 4 : 5)));
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 9) {
+    return n < 0 ? (n > -100000
+                        ? (n > -1000 ? (n > -10 ? 1 : (n > -100 ? 2 : 3)) : (n > -10000 ? 4 : 5))
+                        : (n > -10000000 ? (n > -1000000 ? 6 : 7) : (n > -1000000000 ? (n > -100000000 ? 8 : 9) : 10)))
+                 : (n < 100000
+                        ? (n < 1000 ? (n < 10 ? 1 : (n < 100 ? 2 : 3)) : (n < 10000 ? 4 : 5))
+                        : (n < 10000000 ? (n < 1000000 ? 6 : 7) : (n < 1000000000 ? (n < 100000000 ? 8 : 9) : 10)));
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 18) {
+    return n < 0
+               ? (n > -1000000000L
+                      ? (n > -10000L ? (n > -100L ? (n > -10L ? 1 : 2) : (n > -1000L ? 3 : 4))
+                                     : (n > -1000000L ? (n > -100000L ? 5 : 6)
+                                                      : (n > -10000000L ? 7 : (n > -100000000L ? 8 : 9))))
+                      : (n > -100000000000000L
+                             ? (n > -1000000000000L ? (n > -10000000000L ? 10 : (n > -100000000000L ? 11 : 12))
+                                                    : (n > -10000000000000L ? 13 : 14))
+                             : (n > -10000000000000000L
+                                    ? (n > -1000000000000000L ? 15 : 16)
+                                    : (n > -1000000000000000000L ? (n > -100000000000000000L ? 17 : 18) : 19))))
+               : (n < 1000000000L
+                      ? (n < 10000L
+                             ? (n < 100L ? (n < 10L ? 1 : 2) : (n < 1000L ? 3 : 4))
+                             : (n < 1000000L ? (n < 100000L ? 5 : 6) : (n < 10000000L ? 7 : (n < 100000000L ? 8 : 9))))
+                      : (n < 100000000000000L
+                             ? (n < 1000000000000L ? (n < 10000000000L ? 10 : (n < 100000000000L ? 11 : 12))
+                                                   : (n < 10000000000000L ? 13 : 14))
+                             : (n < 10000000000000000L
+                                    ? (n < 1000000000000000L ? 15 : 16)
+                                    : (n < 1000000000000000000L ? (n < 100000000000000000L ? 17 : 18) : 19))));
+  }
+
+  else {
+    // Note: below ugly template lambda can be replaced with 'static_assert(false);' in C++23
+    []<bool flag = false>() { static_assert(flag, "unknown digits10 value"); }();
+  }
+}
+
+/// Return the number of digits of given integral.
+/// Maximum of int(log2(std::numeric_limits<T>::digits10)) + 1 comparisons.
+constexpr int ndigits(std::unsigned_integral auto n) noexcept {
+  using T = decltype(n);
+
+  if constexpr (std::numeric_limits<T>::digits10 == 2) {
+    return n < 10U ? 1 : (n < 100U ? 2 : 3);
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 4) {
+    return n < 100U ? (n < 10U ? 1 : 2) : (n < 1000U ? 3 : (n < 10000U ? 4 : 5));
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 9) {
+    return n < 100000U ? (n < 1000U ? (n < 10U ? 1 : (n < 100U ? 2 : 3)) : (n < 10000U ? 4 : 5))
+                       : (n < 10000000U ? (n < 1000000U ? 6 : 7) : (n < 1000000000U ? (n < 100000000U ? 8 : 9) : 10));
+  }
+
+  else if constexpr (std::numeric_limits<T>::digits10 == 19) {
+    return n < 10000000000UL
+               ? (n < 1000000UL
+                      ? (n < 1000UL ? (n < 100UL ? (n < 10UL ? 1 : 2) : 3) : (n < 100000UL ? (n < 10000UL ? 4 : 5) : 6))
+                      : (n < 100000000UL ? (n < 10000000UL ? 7 : 8) : (n < 1000000000UL ? 9 : 10)))
+               : (n < 10000000000000000UL
+                      ? (n < 10000000000000UL ? (n < 1000000000000UL ? (n < 100000000000UL ? 11 : 12) : 13)
+                                              : (n < 1000000000000000UL ? (n < 100000000000000UL ? 14 : 15) : 16))
+                      : (n < 1000000000000000000UL ? (n < 100000000000000000UL ? 17 : 18)
+                                                   : (n < 10000000000000000000UL ? 19 : 20)));
+  }
+
+  else {
+    // Note: below ugly template lambda can be replaced with 'static_assert(false);' in C++23
+    []<bool flag = false>() { static_assert(flag, "unknown digits10 value"); }();
+  }
+}
+
+}  // namespace cct
\ No newline at end of file
diff --git a/src/tech/include/overflow-check.hpp b/src/tech/include/overflow-check.hpp
index a0c7782a..75d8c055 100644
--- a/src/tech/include/overflow-check.hpp
+++ b/src/tech/include/overflow-check.hpp
@@ -2,7 +2,6 @@
 
 #include <concepts>
 #include <limits>
-#include <type_traits>
 
 namespace cct {
 
diff --git a/src/tech/include/static_string_view_helpers.hpp b/src/tech/include/static_string_view_helpers.hpp
index f5df4d4d..a1cc307d 100644
--- a/src/tech/include/static_string_view_helpers.hpp
+++ b/src/tech/include/static_string_view_helpers.hpp
@@ -5,7 +5,7 @@
 #include <cstdint>
 #include <string_view>
 
-#include "mathhelpers.hpp"
+#include "nchars.hpp"
 
 namespace cct {
 
diff --git a/src/tech/include/stringhelpers.hpp b/src/tech/include/stringhelpers.hpp
index 1c191502..3bf066de 100644
--- a/src/tech/include/stringhelpers.hpp
+++ b/src/tech/include/stringhelpers.hpp
@@ -6,13 +6,12 @@
 #include <limits>
 #include <string_view>
 #include <system_error>
-#include <type_traits>
 
 #include "cct_config.hpp"
 #include "cct_exception.hpp"
 #include "cct_fixedcapacityvector.hpp"
 #include "cct_string.hpp"
-#include "mathhelpers.hpp"
+#include "nchars.hpp"
 
 namespace cct {
 
diff --git a/src/tech/include/timedef.hpp b/src/tech/include/timedef.hpp
index fa66ab0c..82c20163 100644
--- a/src/tech/include/timedef.hpp
+++ b/src/tech/include/timedef.hpp
@@ -39,4 +39,5 @@ constexpr int64_t TimestampToMillisecondsSinceEpoch(TimePoint tp) {
 constexpr int64_t TimestampToUs(TimePoint tp) {
   return std::chrono::duration_cast<microseconds>(tp.time_since_epoch()).count();
 }
+
 }  // namespace cct
diff --git a/src/tech/include/timestring.hpp b/src/tech/include/timestring.hpp
index 54f18f85..f6ba7cbc 100644
--- a/src/tech/include/timestring.hpp
+++ b/src/tech/include/timestring.hpp
@@ -31,4 +31,5 @@ Nonce Nonce_TimeSinceEpochInMs(Duration delay = Duration{});
 /// Create a Nonce in literal format.
 /// Example: '2021-06-01T14:44:13'
 inline Nonce Nonce_LiteralDate(const char* format) { return ToString(Clock::now(), format); }
+
 }  // namespace cct
diff --git a/src/tech/include/toupperlower.hpp b/src/tech/include/toupperlower.hpp
index 2bbe3df9..d23b54ca 100644
--- a/src/tech/include/toupperlower.hpp
+++ b/src/tech/include/toupperlower.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 namespace cct {
+
 /// constexpr version of std::toupper with chars, as unfortunately for now (May 2021) std::toupper is not constexpr
 constexpr char toupper(char ch) noexcept {
   switch (ch) {
diff --git a/src/tech/include/url-encode.hpp b/src/tech/include/url-encode.hpp
index e23fc261..a113161b 100644
--- a/src/tech/include/url-encode.hpp
+++ b/src/tech/include/url-encode.hpp
@@ -32,7 +32,6 @@ string URLEncode(std::span<const char> data, IsNotEncodedFunc isNotEncodedFunc)
 
 // const char * argument is deleted because it would construct into a span including the unwanted null
 // terminating character. Use span directly, or string / string_view instead.
-
 template <class IsNotEncodedFunc>
 string URLEncode(const char*, IsNotEncodedFunc) = delete;
 
diff --git a/src/tech/src/simpletable.cpp b/src/tech/src/simpletable.cpp
index e48a80af..ebfab06e 100644
--- a/src/tech/src/simpletable.cpp
+++ b/src/tech/src/simpletable.cpp
@@ -12,7 +12,8 @@
 #include <variant>
 
 #include "cct_smallvector.hpp"
-#include "mathhelpers.hpp"
+#include "ipow.hpp"
+#include "nchars.hpp"
 
 namespace cct {
 
diff --git a/src/tech/test/ipow_test.cpp b/src/tech/test/ipow_test.cpp
new file mode 100644
index 00000000..246a3c55
--- /dev/null
+++ b/src/tech/test/ipow_test.cpp
@@ -0,0 +1,28 @@
+#include "ipow.hpp"
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <limits>
+
+namespace cct {
+
+TEST(MathHelpers, Power) {
+  EXPECT_EQ(ipow(3, 2), 9);
+  EXPECT_EQ(ipow(4, 3), 64);
+  EXPECT_EQ(ipow(-3, 3), -27);
+  EXPECT_EQ(ipow(-2, 1), -2);
+  EXPECT_EQ(ipow(17, 5), 1419857);
+  EXPECT_EQ(ipow(10, 10), 10000000000);
+  static_assert(ipow(5, 3) == 125);
+  static_assert(ipow(-7, 0) == 1);
+}
+
+TEST(MathHelpers, Power10) {
+  EXPECT_EQ(ipow10(0), 1);
+  EXPECT_EQ(ipow10(1), 10);
+  EXPECT_EQ(ipow10(2), 100);
+  EXPECT_EQ(ipow10(10), 10000000000);
+  static_assert(ipow10(3) == 1000);
+}
+}  // namespace cct
\ No newline at end of file
diff --git a/src/tech/test/mathhelpers_test.cpp b/src/tech/test/ndigits_test.cpp
similarity index 92%
rename from src/tech/test/mathhelpers_test.cpp
rename to src/tech/test/ndigits_test.cpp
index ee2d53bd..bcf0c547 100644
--- a/src/tech/test/mathhelpers_test.cpp
+++ b/src/tech/test/ndigits_test.cpp
@@ -1,4 +1,4 @@
-#include "mathhelpers.hpp"
+#include "ndigits.hpp"
 
 #include <gtest/gtest.h>
 
@@ -7,25 +7,6 @@
 
 namespace cct {
 
-TEST(MathHelpers, Power) {
-  EXPECT_EQ(ipow(3, 2), 9);
-  EXPECT_EQ(ipow(4, 3), 64);
-  EXPECT_EQ(ipow(-3, 3), -27);
-  EXPECT_EQ(ipow(-2, 1), -2);
-  EXPECT_EQ(ipow(17, 5), 1419857);
-  EXPECT_EQ(ipow(10, 10), 10000000000);
-  static_assert(ipow(5, 3) == 125);
-  static_assert(ipow(-7, 0) == 1);
-}
-
-TEST(MathHelpers, Power10) {
-  EXPECT_EQ(ipow10(0), 1);
-  EXPECT_EQ(ipow10(1), 10);
-  EXPECT_EQ(ipow10(2), 100);
-  EXPECT_EQ(ipow10(10), 10000000000);
-  static_assert(ipow10(3) == 1000);
-}
-
 TEST(MathHelpers, NDigitsS8) {
   EXPECT_EQ(ndigits(static_cast<int8_t>(0)), 1);
   EXPECT_EQ(ndigits(static_cast<int8_t>(3)), 1);
@@ -39,6 +20,16 @@ TEST(MathHelpers, NDigitsS8) {
   static_assert(ndigits(std::numeric_limits<int8_t>::min()) == 3);
 }
 
+TEST(MathHelpers, NDigitsChar) {
+  EXPECT_EQ(ndigits(static_cast<char>(0)), 1);
+  EXPECT_EQ(ndigits(static_cast<char>(3)), 1);
+  EXPECT_EQ(ndigits(static_cast<char>(78)), 2);
+  EXPECT_EQ(ndigits(static_cast<char>(112)), 3);
+
+  static_assert(ndigits(std::numeric_limits<char>::max()) == 3);
+  static_assert(ndigits(std::numeric_limits<char>::min()) == 3);
+}
+
 TEST(MathHelpers, NDigitsS16) {
   EXPECT_EQ(ndigits(static_cast<int16_t>(0)), 1);
   EXPECT_EQ(ndigits(static_cast<int16_t>(3)), 1);