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cipherCaesar.cpp
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cipherCaesar.cpp
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#include <iostream>
using namespace std;
void convertAsciiToChar(char ascii, int indexAlphaLower, int indexAlphaUpper, string& cipherText)
{
if (isalpha(ascii))
{
if (isupper(ascii))
{
indexAlphaUpper += static_cast<int>('A');
cipherText.push_back(indexAlphaUpper);
}
else if (islower(ascii))
{
indexAlphaLower += static_cast<int>('a');
cipherText.push_back(indexAlphaLower);
}
}
else
{
cipherText.push_back(ascii);
}
}
string encryptText(string plainText, int offset)
{
string cipherText;
for (int i = 0; i < plainText.size(); i++)
{
char ascii = plainText[i];
int indexAlphaLower = (static_cast<int>(ascii) + 7 + offset) % 26;
int indexAlphaUpper = (static_cast<int>(ascii) - 13 + offset) % 26;
convertAsciiToChar(ascii, indexAlphaLower, indexAlphaUpper, cipherText);
}
return cipherText;
}
string decryptText(string cipherText, int offset)
{
string decipherText;
for (int i = 0; i < cipherText.size(); i++)
{
char ascii = cipherText[i];
int indexAlphaLower = (static_cast<int>(ascii) + 7 - offset) % 26;
int indexAlphaUpper = (static_cast<int>(ascii) - 13 - offset) % 26;
convertAsciiToChar(ascii, indexAlphaLower, indexAlphaUpper, decipherText);
}
return decipherText;
}
int main()
{
string text = "@bcD3 fghijk !mn0pqr stuVwx Yz";
int offset = 7;
string cipherText = encryptText(text, offset);
cout << "cipher text: " << cipherText << "\n";
cout << "decipher text: " << decryptText(cipherText, offset) << "\n";
}