rot13.cpp

// Demonstrate the common "ROT13" version of the Caesar cipher.
 
#include <iostream>
#include <z/all.hpp>
 
// Caesar cipher function
template <int N>
auto rot(uint32_t chr) -> uint32_t {
    if (z::core::isLowerAlpha(chr)) {
        return ((chr - 'a') + N) % 26 + 'a';
    } else if (z::core::isUpperAlpha(chr)) {
        return ((chr - 'A') + N) % 26 + 'A';
    }
 
    return chr;
}
 
// Alias strings that can also perform rot13.
const zstring from = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
const zstring to = "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM";
 
int main(int argc, char **argv) {
    for (int i = 1; i < argc; ++i) {
        auto str = zstring(argv[i]) + " ";
 
        // The easiest way is to use two sets of characters to perform the cipher.
        // These just map characters from one to the other.
        str.cipher(from, to).write(std::cout);
 
        // Alternatively, you can pass a function in to perform the cipher.
        // This is almost always faster than mapping with the `to`/`from` strings,
        // And allows for more dynamic ciphers.
        str.cipher(rot<13>).write(std::cout);
    }
    zstring().writeln(std::cout);
}