Code:#include <iostream> #include <iomanip> #include <string.h> using namespace::std; void encrypt(char string[], char key[]); void decrypt(char string[], char key[]); int main() { int again; char string[81]; char key[]="123456789ZBCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJK123456789"; do { cout << "Enter a word or sentence up to 80 characters: " << endl; gets(string); encrypt(string, key); decrypt(string, key); cout << "Want to enter another? (1 for yes, 2 for no)" << endl; cin >> again; } while (again == 1); return 0; } void encrypt(char string[], char key[]) { for(int x = 0; x < strlen(string); x++) { string[x] = string[x]^key[x]; cout << string[x]; } cout<<endl; } void decrypt(char string[], char key[]) { for(int x=0; x < strlen(string); x++) { string[x] = string[x]^key[x]; cout << string[x]; } cout<<endl; }