Help to fix this please. This is a vigenere cipher implemented in C++.

It gives me an error saying terninate called after throwing an instance of 'std::bad_alloc' what(): std::bad_alloc

#include

#include

#include

using namespace std;

string expandKey(string plainText, string key)

{

int msgLen = plainText.size();

int keyLen = key.size();

for (int i = 0; ; i++)

{

if (msgLen == i)

i = 0;

if (keyLen == msgLen)

break;

key.push_back(key[i]);

}

return key;

}

string encrypt(string plainText, string key)

{

string cipherText;

int len = plainText.size();

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

{

int letter = ((plainText[i] + key[i]) % 26) + 'A';

cipherText.push_back(letter);

}

return cipherText;

}

string removeSpaces(string msg)

{

int len = msg.size();

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

{

if(msg[i] == ' ')

msg.erase(i, 1);

}

return msg;

}

int main()

{

string plainText;

string key = "SMITH";

cout << "Please enter the message to be encrypted: ";

getline(cin,plainText);

plainText = removeSpaces(plainText);

string newKey = expandKey(plainText, key);

string cipherText = encrypt(plainText, newKey);

cout << "Encrypted Message: " << cipherText << " ";

return 0;

}