Tech recruiter competency test encoder

RecruiterTestGen.cpp

#include <iostream>
#include <sstream>
#include <string>
#include <random>

using std::string;
using std::ostringstream;

const int arraySize = 10;
const int charSpace = 97;
const int offset = 31;
const int lowerboundCodepoint = 12353; // Japanese hiragana beginning
const int upperboundCodepoint = 12543; // Japanese katakana ending
auto toEncode = string{"EncryptionTeXt!\n"};

//Randomness
std::default_random_engine generator(std::chrono::system_clock::now().time_since_epoch().count());
std::uniform_int_distribution<int> distribution(lowerboundCodepoint / charSpace, upperboundCodepoint / charSpace); // if ubCP | charSpace, then last region is useless, but who cares?
static_assert(upperboundCodepoint - lowerboundCodepoint >= charSpace, "Not enough room to encode character space one-to-one");

//http://dev.networkerror.org/utf8/?start=12500&end=12600&cols=4&show_uni_int=on&show_uni_hex=on&show_html_ent=on&show_raw_hex=on&show_raw_bin=on

string utf8chr(int cp) {
    char c[5]={ 0x00,0x00,0x00,0x00,0x00 };
    if     (cp<=0x7F) { c[0] = cp;  }
    else if(cp<=0x7FF) { c[0] = (cp>>6)+192; c[1] = (cp&63)+128; }
    else if(0xd800<=cp && cp<=0xdfff) {} //invalid block of utf8
    else if(cp<=0xFFFF) { c[0] = (cp>>12)+224; c[1]= ((cp>>6)&63)+128; c[2]=(cp&63)+128; }
    else if(cp<=0x10FFFF) { c[0] = (cp>>18)+240; c[1] = ((cp>>12)&63)+128; c[2] = ((cp>>6)&63)+128; c[3]=(cp&63)+128; }
    return string(c);
}

string getUnicodeEncoded(char c) {
  if (c != '\n' && (c < 32 || c > 127))
    throw string{"Ordinal not in encoding range! Must be text or newline."};
  if (c == '\n')
    c = 31; // convert \n to locale unit seperator
  c -= 31; // Normalize so newline is 0

  // Get the encoded character
  string encodedChar;
  int codepoint;
  while (encodedChar.empty()) {
    codepoint = distribution(generator) * charSpace + c;
    if (codepoint < lowerboundCodepoint || codepoint > upperboundCodepoint)
      continue;
    encodedChar = utf8chr(codepoint);
  }
  return encodedChar;
}

int main() {
  // printf is nicer than cout -- sorry!
  printf("const char* encoded[%d];\n", arraySize);
  for (int i = 0; i < arraySize; ++i) {
    ostringstream encoded;
    for (int j = 0; j < toEncode.size(); ++j) {
      encoded << getUnicodeEncoded(toEncode[j]);
    }
    printf("encoded[%d] = \"%s\";\n", i, encoded.str().c_str());
  }
}