Can you convert this C++ code to a C code?

// C++ code to implement Vigenere Cipher #include using namespace std;

// This function generates the key in // a cyclic manner until it's length isn't // equal to the length of original text string generateKey(string str, string key) { int x = str.size();

for (int i = 0; ; i++) { if (x == i) i = 0; if (key.size() == str.size()) break; key.push_back(key[i]); } return key; }

// This function returns the encrypted text // generated with the help of the key string cipherText(string str, string key) { string cipher_text;

for (int i = 0; i < str.size(); i++) { // converting in range 0-25 char x = (str[i] + key[i]) %26;

// convert into alphabets(ASCII) x += 'A';

cipher_text.push_back(x); } return cipher_text; }

// This function decrypts the encrypted text // and returns the original text string originalText(string cipher_text, string key) { string orig_text;

for (int i = 0 ; i < cipher_text.size(); i++) { // converting in range 0-25 char x = (cipher_text[i] - key[i] + 26) %26;

// convert into alphabets(ASCII) x += 'A'; orig_text.push_back(x); } return orig_text; }

// Driver program to test the above function int main() { string str = "GEEKSFORGEEKS"; string keyword = "AYUSH";

string key = generateKey(str, keyword); string cipher_text = cipherText(str, key);

cout << "Ciphertext : " << cipher_text << " ";

cout << "Original/Decrypted Text : " << originalText(cipher_text, key); return 0; }