C#•2y ago

Caesar shift

Hi, I'm making a C# program and part of it is based on a Caesar shift. I have searched examples of Caesar shifts online but I do not really understand how they work, for example some use modulus. I want to know how I can make it so if a character like Z is shifted forward by 1 letter it will loop back to A. Thank you! :D

6 Replies

MODiX•2y ago

TheRanger#3357

REPL Result: Success

public static char ShiftBy(char c, int i)
{
    int index = c-'A';
    index = (index + i) % 26;
    return (char)('A' + index);
}
    char c = 'Z';
    Console.WriteLine(ShiftBy(c, 2));

public static char ShiftBy(char c, int i)
{
    int index = c-'A';
    index = (index + i) % 26;
    return (char)('A' + index);
}
    char c = 'Z';
    Console.WriteLine(ShiftBy(c, 2));

Console Output

Compile: 589.674ms | Execution: 67.987ms | React with ❌ to remove this embed.

icy•2y ago

thank you, i'm not entirely sure how this code works though, what is the modulus for?

Klarth•2y ago

The modulus is for array wrapping. ie. You have an array of [A-Z] with indices [0-25]. So if you add one to Z, you get index 26 -> 0, which is A.

icy•2y ago

ohh, why does that work? I thought the modulus was for remainders is this a second use?

Tvde1•2y ago

this is the remainer 26 / 25 is 1 with a remainder of 1 if you would shift 'Z' by 105, you would get (25 + 105) % 25 = 5

icy•2y ago

ohhh i see thank you

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Caesar shift