如何解决C++ Vigenere 和 Caesar 密码在同一个程序中使用 switch case
在第一个代码中，我做了一个凯撒密码，它运行良好。但是，我不能添加 Vigenere。有一个类和一些指针，但它们在 like "###_#" | 0 Results
not like "###_#" | 3 Results
-switch 语句中不起作用，所以我需要帮助。
- 加密部分是 switch case :3
- 解密部分是 switch case :4
caseVigenere 部分：
#include <iostream>
#include <string.h>
#include <string>
using namespace std;
char message[200],ch;
int i,key;
string k,output,messageV;
int menu(int answer);
int main()
{
int answer;
bool keepLooping = true;
while (keepLooping)
{
cout << "Pick a Choice from the List: \n(1)Caesar \n(2)Vigenere \n ";
cin >> answer;
if (answer == 1)
{
while(keepLooping)
{
cout << "Pick a Choice from the List: \n(1)Encryption\n(2)Decryption \n ";
cin >> answer;
if (answer == 1)
{
answer = 1;
keepLooping = false ;
}
else if(answer == 2)
{
answer = 2;
keepLooping = false;
}
else
{
keepLooping = true;
}
}
}
else if(answer == 2)
{
while(keepLooping)
{
cout << "Pick a Choice from the List: \n(1)Encryption\n(2)Decryption \n ";
cin >> answer;
if (answer == 1)
{
answer = 3;
keepLooping = false ;
}
else if(answer == 2)
{
answer = 4;
keepLooping = false;
}
else
{
keepLooping = true;
}
}
}
else
{
keepLooping = true;
}
}
menu(answer);
}
int menu(int answer)
{
switch (answer)
{
case 1://Caesar Cipher Encryption
cout << "Enter a message to encrypt: ";
cin.ignore();
cin.getline(message,200);
cout << "Enter key: ";
cin >> key;
for(i = 0; message[i] != '\0'; ++i){
ch = message[i];
if(ch >= 'a' && ch <= 'z'){
ch = ch + key;
if(ch > 'z'){
ch = ch - 'z' + 'a' - 1;
}
message[i] = ch;
}
else if(ch >= 'A' && ch <= 'Z'){
ch = ch + key;
if(ch > 'Z'){
ch = ch - 'Z' + 'A' - 1;
}
message[i] = ch;
}
}
cout << "Encrypted message: " << message;
break;
case 2://Caesar Cipher Decryption
cout << "Enter a message to decrypt: ";
cin.ignore();
cin.getline(message,200);
cout << "Enter key: ";
cin >> key;
for(i = 0; message[i] != '\0'; ++i){
ch = message[i];
if(ch >= 'a' && ch <= 'z'){
ch = ch - key;
if(ch < 'a'){
ch = ch + 'z' - 'a' + 1;
}
message[i] = ch;
}
else if(ch >= 'A' && ch <= 'Z'){
ch = ch - key;
if(ch > 'a'){
ch = ch + 'Z' - 'A' + 1;
}
message[i] = ch;
}
}
cout << "Decrypted message: " << message;
break;
case 3:
cout << "CASE 3";
break;
case 4:
cout << "CASE 4";
break;
default:
cout << "There is no choices." << endl;
}
return answer;
}
解决方法
我的建议是你试着在你的两个程序中找到共同的模式。例如，您必须使用加密和解密的方法。可以将其抽象为两个不同的类，也许使用一个定义接口的公共基类（允许多态之类的东西）：
struct Cipher
{
virtual std::string encryption(std::string const&) = 0;
virtual std::string decryption(std::string const&) = 0;
};
class Caesar : public Cipher
{
public:
std::string encryption(std::string const& s) override
{
// TODO: Implement Caesar cipher encryption
}
std::string decryption(std::string const& s) override
{
// TODO: Implement Caesar cipher decryption
}
};
class Vigenere : public Cipher
{
public:
std::string encryption(std::string const& s) override
{
// TODO: Implement Vigenere cipher encryption
}
std::string decryption(std::string const& s) override
{
// TODO: Implement Vigenere cipher decryption
}
};
由此我们可以创建一组函数来使用任何密码（通过指向基 Cipher 类的指针）。让我们从选择要使用的密码开始：
Cipher* select_cipher()
{
std::cout << "Please select cipher to use:\n";
std::cout << "1) Caesar\n";
std::cout << "2) Vigenere\n";
int selection;
std::cin >> selection;
if (selection == 1)
{
return new Caesar;
}
else if (selection == 2)
{
return new Vigenere;
}
else
{
return nullptr;
}
}
现在我们有一个密码可以使用，然后选择要做什么：
int select_method()
{
std::cout << "Do you want to encrypt or decrypt?\n";
std::cout << "1) Encrypt\n";
std::cout << "2) Decrypt\n";
int method;
std::cin >> method;
return method;
}
现在我们真的拥有了使用任何支持的密码和方法所需的一切：
int main()
{
Cipher* cipher = select_cipher();
int method = select_method();
std::string input;
std::string result;
// TODO: Read input string to encrypt or decrypt
if (method == 1)
{
result = cipher->encryption(input);
}
else if (method == 2)
{
result = cipher->decryption(input);
}
std::cout << "Result = " << result << '\n';
}
请注意，这只是一个非常粗略的概述，还有很多部分缺失（例如实际的加密和解密算法）。这些留给读者作为练习。
您当然可以使用 if ... else if ... 代替 switch。但对于这些简单的情况，这并不重要，而且 if ... else if ... 是 IMO，更易于阅读。
我已经编码了，你也可以检查一下吗？
#include <iostream>
#include <string>
using namespace std;
class Vig {
public:
string k;
Vig(string k) {
for (int i = 0; i < k.size(); ++i) {
if (k[i] >= 'A' && k[i] <= 'Z')
this->k += k[i];
else if (k[i] >= 'a' && k[i] <= 'z')
this->k += k[i] + 'A' - 'a';
}
}
string Vegencryption(string t) {
string output;
for (int i = 0,j = 0; i < t.length(); ++i) {
char c = t[i];
if (c >= 'a' && c <= 'z')
c += 'A' - 'a';
else if (c < 'A' || c > 'Z')
continue;
output += (c + k[j] - 2 * 'A') % 26 + 'A'; //added 'A' to bring it in range of ASCII alphabet [ 65-90 | A-Z ]
j = (j + 1) % k.length();
}
return output;
}
string Vegdecryption(string t) {
string output;
for (int i = 0,j = 0; i < t.length(); ++i) {
char c = t[i];
if (c >= 'a' && c <= 'z')
c += 'A' - 'a';
else if (c < 'A' || c > 'Z')
continue;
output += (c - k[j] + 26) % 26 + 'A';//added 'A' to bring it in range of ASCII alphabet [ 65-90 | A-Z ]
j = (j + 1) % k.length();
}
return output;
}
string Cesencryption(string t,int key){
string output;
char ch;
for(int i = 0; t[i] != '\0'; ++i){
ch = t[i];
if(ch >= 'a' && ch <= 'z'){
ch = ch + key;
if(ch > 'z'){
ch = ch - 'z' + 'a' - 1;
}
t[i] = ch;
}
else if(ch >= 'A' && ch <= 'Z'){
ch = ch + key;
if(ch > 'Z'){
ch = ch - 'Z' + 'A' - 1;
}
t[i] = ch;
}
}
output = t;
return output;
}
string Cesdencryption(string t,int key){
string output;
char ch;
for(int i = 0; t[i] != '\0'; ++i){
ch = t[i];
if(ch >= 'a' && ch <= 'z'){
ch = ch - key;
if(ch < 'a'){
ch = ch + 'z' - 'a' + 1;
}
t[i] = ch;
}
else if(ch >= 'A' && ch <= 'Z'){
ch = ch - key;
if(ch > 'a'){
ch = ch + 'Z' - 'A' + 1;
}
t[i] = ch;
}
}
output = t;
return output;
}
};
int main() {
char message[200];
string key;
int choice;
cout << "Pick a Choice from the List: \n(1)Caesar \n(2)Vigenere \n ";
cin >> choice;
if(choice == 2) //Vigenere
{
cout << "Pick a Choice from the List: \n(1)Encryption\n(2)Decryption \n ";
cin >> choice;
if (choice == 1)
{
cout << "Key: ";
cin >> key;
cin.ignore();
Vig v(key);
cout << "Enter a message to encrypt: ";
cin.getline(message,200);
string ori = message;
string encrypt = v.Vegencryption(ori);
cout << "Encrypted Message: " << encrypt << endl;
}
else if (choice == 2)
{
cout << "Key: ";
cin >> key;
cin.ignore();
Vig v(key);
cout << "Enter a message to encrypt: ";
cin.getline(message,200);
string ori = message;
string decrypt = v.Vegdecryption(ori);
cout << "Decrypted Message: " << decrypt << endl;
}
else
{
cout << "You Exit the Program.";
}
}
else if (choice == 1) //Ceaser
{
cout << "Pick a Choice from the List: \n(1)Encryption\n(2)Decryption \n ";
cin >> choice;
if (choice == 1)
{
int key;
cout << "Enter a message to encrypt: ";
cin.ignore();
cin.getline(message,200);
cout << "Enter key: ";
cin >> key;
Vig v(message);
string ori = message;
string decrypt = v.Cesencryption(ori,key);
cout << "Decrypted Message: " << decrypt << endl;
}
else if (choice == 2)
{
int key;
cout << "Enter a message to dencrypt: ";
cin.ignore();
cin.getline(message,200);
cout << "Enter key: ";
cin >> key;
Vig v(message);
string ori = message;
string encryption = v.Cesdencryption(ori,key);
cout << "Decrypted Message: " << encryption << endl;
}
else
{
cout << "You Exit the Program.";
}
}
else
{
cout << "You Exit the Program.";
}
}
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