fix: Integer conversion logic (#394)

Author: hhvrc

include/util/DigitCounter.h

@@ -11,17 +11,31 @@ namespace OpenShock::Util {
  template<typename T>
  constexpr std::size_t Digits10Count(T val)
  {
- static_assert(std::is_integral_v<T>);
+ using Decayed = std::remove_cv_t<std::remove_reference_t<T>>;
+ static_assert(std::is_integral_v<Decayed>);
+
+ using U = std::make_unsigned_t<Decayed>;
 
  std::size_t digits = 1;
+ U u;
 
- if constexpr (std::is_signed_v<T> && val < 0) {
- digits++;
- val = -val;
+ if constexpr (std::is_signed_v<Decayed>) {
+ if (val < 0) {
+ // Account for the sign
+ digits++;
+
+ // Safe magnitude via unsigned modular negation
+ u = U(0) - static_cast<U>(val);
+ } else {
+ u = static_cast<U>(val);
+ }
+ } else {
+ u = static_cast<U>(val);
  }
 
- while (val >= 10) {
- val /= 10;
+ // Now count digits of u (magnitude), base-10
+ while (u >= 10) {
+ u /= 10;
  digits++;
  }
 

src/Convert.cpp

@@ -17,22 +17,38 @@ void fromNonZeroT(T val, std::string& out)
 {
  // Ensure the template type T is an integral type
  static_assert(std::is_integral_v<T>, "T must be an integral type");
+ using U = std::make_unsigned_t<T>;
+
  constexpr std::size_t MaxDigits = OpenShock::Util::Digits10CountMax<T>;
 
  char buf[MaxDigits];
 
  // Start from the end of the buffer to construct the number in reverse (from least to most significant digit)
- char* ptr = buf + MaxDigits;
+ char* const end = buf + MaxDigits;
+ char* ptr = end;
 
- bool negative = val < 0;
- if (negative) {
- val = -val; // Make the value positive for digit extraction
+ U u;
+ bool negative = false;
+
+ if constexpr (std::is_signed_v<T>) {
+ if (val < 0) {
+ negative = true;
+
+ // Convert to unsigned, then take the modular negation.
+ // This is well-defined and yields the magnitude of val.
+ u = U(0) - U(val);
+ } else {
+ u = U(val);
+ }
+ } else {
+ // Unsigned types: just use the value as-is.
+ u = U(val);
  }
 
  // Extract digits and store them in reverse order in the buffer
- while (val > 0) {
- *--ptr = '0' + (val % 10);
- val /= 10;
+ while (u > 0) {
+ *--ptr = char('0' + (u % 10));
+ u /= 10;
  }
 
  // If the number was negative, add the negative sign
@@ -41,7 +57,7 @@ void fromNonZeroT(T val, std::string& out)
  }
 
  // Append the resulting string to the output
- out.append(ptr, buf + MaxDigits);
+ out.append(ptr, end - ptr);
 }
 
 // Base converter