Function ParseInt32

deps/google-benchmark/src/commandlineflags.cc:34–64

Parses 'str' for a 32-bit signed integer. If successful, writes the result to *value and returns true; otherwise leaves *value unchanged and returns false.

// the result to *value and returns true; otherwise leaves *value
// unchanged and returns false.
bool ParseInt32(const std::string& src_text, const char* str, int32_t* value) {
  // Parses the environment variable as a decimal integer.
  char* end = nullptr;
  const long long_value = strtol(str, &end, 10);  // NOLINT

  // Has strtol() consumed all characters in the string?
  if (*end != '\0') {
    // No - an invalid character was encountered.
    std::cerr << src_text << " is expected to be a 32-bit integer, "
              << "but actually has value \"" << str << "\".\n";
    return false;
  }

  // Is the parsed value in the range of an Int32?
  const int32_t result = static_cast<int32_t>(long_value);
  if (long_value == std::numeric_limits<long>::max() ||
      long_value == std::numeric_limits<long>::min() ||
      // The parsed value overflows as a long.  (strtol() returns
      // LONG_MAX or LONG_MIN when the input overflows.)
      result != long_value
      // The parsed value overflows as an Int32.
  ) {
    std::cerr << src_text << " is expected to be a 32-bit integer, "
              << "but actually has value \"" << str << "\", "
              << "which overflows.\n";
    return false;
  }

  *value = result;
  return true;
}

// Parses 'str' for a double.  If successful, writes the result to *value and
// returns true; otherwise leaves *value unchanged and returns false.