C++ Problem

How to fix segmentation fault in this problem? Please only modify function specified. We need to get a secret message as the answer

#include

#include

// taken from http://stackoverflow.com/questions/3381614/c-convert-string-to-hexadecimal-and-vice-versa

// -----DO NOT TOUCH-----

std::string string_to_hex(const std::string & input)

{

static const char* const lut = "0123456789ABCDEF";

size_t len = input.length();

std::string output;

output.reserve(2 * len);

for (size_t i = 0; i < len; ++i)

{

const unsigned char c = input[i];

output.push_back(lut[c >> 4]);

output.push_back(lut[c & 15]);

}

return output;

}

// recursive function to reverse a string

// ONLY MODIFY THIS

std::string ReverseText(std::string & msg, int start = 0, int end = -1)

{

if (end == -1) end = msg.length() - 1; // init case

if (end < start) return msg; // base case

else

{

char hold = msg[start];

msg[start] = msg[end];

msg[end] = hold;

return ReverseText(msg, start++, end--);

}

}

// A simple loop-based decode function for string

// -----DO NOT TOUCH-----

std::string DecodeText(std::string & msg)

{

size_t len = msg.length();

for (size_t i = 0; i < len; ++i) msg[i] = msg[i] ^ 0x02;

return msg;

}

// decodes a secret message

// -----DO NOT TOUCH-----

int main()

{

std::string secret = "novj,vgpagq]02-q`cn-623qa-wfg,aqw,qgv{`--8rvvj";

std::cout << "secret: " << secret << std::endl;

std::string rev = ReverseText(secret);

std::cout << "Reverse: " << rev << std::endl;

std::string msg = DecodeText(secret);

std::cout << "Message: " << msg << std::endl;

return 0;

}