hello, I'm working on a program to encrypt using Caesar cipher, but the encryption I am receiving one letter only. For example, I input (car) but i receive only the letter (F).

clc
clear all;
close all;
p=input('enter plain text:  ', 's')
p=lower(p);
lp=size(p);

for i=1:lp
    c(i)=int16(p(i))-97+3;
end    
c=mod(c,26)+65;
c=char(c)

Answer 1

[Voss]

lp is a 1-by-2 vector, only the first element of which is used in a colon expression (as you are using it, in defining your for loop). So if p is a row vector, the size of p is 1-by-something, so lp will be [1 something], and the for loop iterates once.

Instead of using size, use numel.

Consider the difference between this:

p = 'car';
lp = size(p)

lp = 1×2

1 3

for i = 1:lp
    disp(['Iteration ' num2str(i)]);
end

Iteration 1

And this:

p = 'car';
lp = numel(p)

lp = 3

for i = 1:lp
    disp(['Iteration ' num2str(i)]);
end

Iteration 1
Iteration 2
Iteration 3