caesar cyphor encryption problem .

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mayank ghugretkar
mayank ghugretkar 2019-6-12
编辑： Karel Octavianus Bachri 2024-4-13，1:27
Caesar's cypher is the simplest encryption algorithm. It adds a fixed value to the ASCII (unicode) value of each character of a text. In other words, it shifts the characters. Decrypting a text is simply shifting it back by the same amount, that is, it substract the same value from the characters. Write a function called caesar that accepts two arguments: the first is the character vector to be encrypted, while the second is the shift amount. The function returns the output argument coded, the encrypted text. The function needs to work with all the visible ASCII characters from space to ~. The ASCII codes of these are 32 through 126. If the shifted code goes outside of this range, it should wrap around. For example, if we shift ~ by 1, the result should be space. If we shift space by -1, the result should be ~.
for the first part of the code...this works
function coded=caesar(A,n)
char_set=char(32):char(126)
coded=char(A+n);
end
But if i want to maintain the range between 32 and 126 ....and also wrap around the same values as asked in later half of question , it doesnt work
function coded=caesar(A,n)
char_set=char(32):char(126)
while A <=char_set
coded=char(A+n);
end
end
please help me with the concerned code buiding ....( expect a simple approach , since iam a begineer)
test for these outputs
caesar('ABCD',1)
ans =
'BCDE'
caesar('xyz ~',1)
ans =
'yz{! '
caesar('xyz ~',-1)
ans =
'wxy~}' %these are correct answers to the code
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Danial Ahmad
Danial Ahmad 2020-9-28
the problem is that e.g if the value of char_vec is 120 i.e x and the shift_amount is let's say 100 then char_value will be 220 and when you subtract 95 form that you dont get the desired result
Rik
Rik 2020-9-28
@Danial, which code are you talking about? Sonu already mentioned their code doesn't work.

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采纳的回答

Yitong Liu
Yitong Liu 2019-8-24
编辑：Yitong Liu 2019-8-24
function coded = caesar(M, n)
num = double(M); %Converts string into double
num2 = num;
N = n - 95 * fix(n/95);
for i = 1:length(num);
if num(i) + N < 32 %If ASCII value goes below 32
num2(i) = 126 - (31- num(i) - N);
elseif num(i) + N > 126 %If ASCII value goes beyond 126
num2(i) = 32 + (num(i) + N -127);
else
num2(i) = num(i) + N ; %If ASCII value goes normal
end
coded = char(num2);
end
I spent halfhour on solving this problem, a little bit hard.
This is correct code. Hope it helps.
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Walter Roberson
Walter Roberson 2021-8-14
Ran in:
@Kartik rao
char(32) to char(126) is a range of 126-32+1 = 95 possibilities. If you were shifting forward, if the original value were large enough, and the shift were large enough, then the total could be greater than 126. For example,
'z' + 23
ans = 145
When that happens, as you count forward from your original letter, when you get to 126, the next value after that should not be 127 but instead should be 32, and you would continue counting from that.
But the shift that the user can request is not restricted; the user could request, for example, a shift of 1000. You would have to have counted through 126, 32, 33, ... 126, 32, 33, ... 126, 32, 33.. several times.
Now, you could write a loop,
while shift_count > 0
current_characters = current_characters + 1;
shift_count = shift_count - 1;
current_characters(current_characters == 127) = 32;
end
but this is not efficient. You could be more efficient by first writing
while shift_count > 95
shift_count = shift_count - 95;
end
A shift count of (say) 200 is equivalent to a shift count of 95 followed by a shift count of 95 followed by a shift count of 10, But a shift count of 95 leaves everything where it was, so that shift count of 200 is equivalent to a shift count of 10: every group of 95 in the shift "wraps back" to the beginning.
But using a loop to make this reduction of the shift count is not as efficient as it should be. Instead you should be able to calculate how many would be left over after you removed all full multiples of 95. And that is a calculation that mod() makes: mod(shift_count, 95) asks "how many is left over after you remove full multiples of 95?": that is what the mod() function is designed for, to calculate remainders after removing integer multiples of a number.
So: mod() is used to remove the effect of "wrapping" past the end of the char(126) end. And it turns out that you can use it to calculate the end-point:
Subtract off the base of 32. Calculate mod(characters_minus_32 + shift_count, 95) . Add back 32, and you have the result you need.

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更多回答（41 个）

Marilou
Marilou 2019-10-17
编辑：DGM 2023-2-26
function coded= caesar(string,shift)
value=string+shift;
for i=1:length(value)
while value(i)<32
value(i)=value(i)+95;
end
while value(i)>126
value(i)=value(i)-95;
end
end
coded=char(value);
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Jobin Geevarghese Thampi
Jobin Geevarghese Thampi 2022-3-21
and for caesar('ABCD',3)
for=1:length(value) means 1:4 right?

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Wilver Sánchez
Wilver Sánchez 2020-2-7
function coded = caesar(text,amound)
n=amound - 95 * fix(amound/95);
v=double(text)+n;
v(v<32)=126-(31-v(v<32));
v(v>126)=32+(-127+v(v>126));
coded=char(v);
end
  2 个评论
Wilver Sánchez
Wilver Sánchez 2020-2-7
I've wrote this code it solves de problem in a different way that the ones I've seen in the previous answers, I hope it can help someone.

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Pavel Radko
Pavel Radko 2020-8-11
编辑：Pavel Radko 2020-8-13
Thanks to a person who told about circshift function. I've been tried several hours to solve this task without that function.
So finaly I've passed all tests. And final code is much shorter and elegant as I have at today's morning ))
It has only 4 lines including the "end".
The main idea is to shift character table, but not the symbols of input.
% Write a function "caesar" that uses as input "array" - array
% of ASCII table characters, and "shift" - the value (integer) of shifting the "array" elements
% via ASCII table (from 32nd to 126th)
function coded = caesar (array,shift)
shifted_array=circshift(char(32:126),-shift);
% we shift (roll) ASCII characters from 32 to 126 on the "shift" amount
% note that we use "-shift", because we shift the character table but not
% the characters in our "array"
% as output we get all ASCII characters from 32 to 126 but shifted (rolled)
coded = shifted_array(double(array)-31)
% double(array) - gets array of numbers that correspond to ASCII character
% table
% (double(array)-31) - this outs array of numbers with caracter indices
% shifted by -31
% "-31" because we use "shifted_array" that hasnt ASCII characters from 1 to 31
% shifted_array() - uses array of numbers in parentheses as shifted table
% indices and outputs corresponding characters from it
end
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Nikhil Sharma
Nikhil Sharma 2021-7-18
function coded = caesar(x,y)
b= double(x)
m = mod(y, 95)
c= b+m
if c>126
c= c-95;
elseif c<32
c = c+95;
end
coded=char(c)
end
Walter Roberson
Walter Roberson 2021-7-18
@Nikhil Sharma
That code can fail if x is a vector, which is the expected case. Consider for example
caeser( char(124:126), 1)
double(char(124:126)) would be [124, 125, 126]. Add 1 to that to get c = [125, 126, 127]. Now you test
if c>126
but c is a vector, and the [125 126] part is not greater than 126, so the if will fail because the test will produce [false,false,true] and if needs the values to be all non-zero for the test to succeed.

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Guillaume
Guillaume 2019-6-12
Use mod or rem to constrain values between 0 and a maximum, with wrap-around.e.g:
>> mod(0:51, 26)
ans =
Columns 1 through 21
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Columns 22 through 42
21 22 23 24 25 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Columns 43 through 52
16 17 18 19 20 21 22 23 24 25
You can see that values 26, 27, ... go back to 0, 1, ...
Add/subtract some offsets to do the same for values in the range 32:126
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Walter Roberson
Walter Roberson 2021-1-9
Ran in:
mod() works for negative shifts too
S = 'xyla'
S = 'xyla'
shift = 5
shift = 5
char('a' + mod(S - 'a' + shift,26))
ans = 'cdqf'
char('a' + mod(S - 'a' - shift,26))
ans = 'stgv'
Manuel Rodríguez Flores
Manuel Rodríguez Flores 2021-8-4
Hello, I've tried this but some of the values in my vector stop appearing or changed to another row when the output is given. I would really appreciate any advice. The code is:
function coded = caesar(v,m)
v = double(v);
v = v + m;
for r = 1:size(v,2) %I tried this to solve the characters dissapearing
v(1,r) = mod(v(1,r),95);
end
coded = char(v);
end

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Zeyuan Cao
Zeyuan Cao 2020-2-7
I came up with an approach which uses logical indexing instead of if statement
function coded=caesar(str,n)
str1=double(str);
m=n-95*floor(n/95);
codedstr1=str1+m;
codedstr1(codedstr1>=127)=codedstr1(codedstr1>=127)-127+32;
coded=char(codedstr1);
end
  1 个评论
Sahil
Sahil 2020-3-19
编辑：DGM 2023-2-26
Dude this only half the solution you missed " message + n < 32 " condition
function coded = caesar(message , n)
msg = double(message);
m = mod(n, 95);
coded_msg = msg + m;
coded_msg(coded_msg > 126) = coded_msg(coded_msg > 126) - 127 + 32;
coded_msg(coded_msg < 32) = coded_msg(coded_msg < 32) + 127 -32;
coded =char(coded_msg);
end

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Sahil
Sahil 2020-3-19
编辑：DGM 2023-2-26
function coded = caesar(message , n)
msg = double(message);
m = mod(n, 95); % this contricts the key within the range
coded_msg = msg + m;
coded_msg(coded_msg > 126) = coded_msg(coded_msg > 126) - 95;
coded_msg(coded_msg < 32) = coded_msg(coded_msg < 32) + 95;
coded =char(coded_msg);
end
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Walter Roberson
Walter Roberson 2021-7-22
Ran in:
@ANDIE MEDDAUGH
Read the problem description:
"The function needs to work with all the visible ASCII characters from space to ~. The ASCII codes of these are 32 through 126"
Now calculate:
length(32:126)
ans = 95
Suleman
Suleman 2023-2-25
% this contricts the key within the range
you mean constrict ?
very good solution

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Cyrus David Pastelero
编辑：Cyrus David Pastelero 2020-7-8
%This is my aproach to the problem.
function coded = caesar(arr, num)
size = strlength(arr);
coded = arr+num
for i = 1:size
while coded(i)> 126
coded(i) = coded(i) - 95;
end
while coded(i) < 32
coded(i) = coded(i) + 95;
end
end
coded = char(coded);
end
CCF2017 MIT
CCF2017 MIT 2019-7-2
编辑：CCF2017 MIT 2019-7-2
This problem is asking you to shift the character variable by a given element n
the word wrap means that if the ASCII code of your character exceeds 32 or 126 you need to circle back again .
For example
if ASCII code is 97 and n (shift variable) is 45 so your ASCII code is 142 which exceeds 126. So you need to subtract 126 from 142
142-126, and add the net result to 31.
you need'nt do all that..... use the function called circshift
so i defined a character array from 32 to 126 which is the required ascii range
ch=char(32:126)
these are the characters.
ch =
' !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
and when i use the circshift command
ch_shift_pos=circshift(ch,2)
ch_shift_pos =
'}~ !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|'
ch_shift_neg=circshift(ch,-2)
ch_shift_neg=
'"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~ !'
Notice how the characters have shifted by 2 positions without you having to manually keep it within its range.
now if i want to find a character and its corresponding encrypted/shifted value i simply transfer the index since both ch and ch_shift are of the same size
so for example: if i want to find the encryption character of a , i first find the index of a in the 'ch' array and store it in a variable called x
x=strfind(ch,'a')
x =
66
and then i use that index to find the encryption in the shifted array
ch_shift_pos(x)
ans =
'_'
ch_shift_neg(x)
ans =
'c'
There! thats your answer. As simple as that. But i had to rack my brains for it. :P
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CCF2017 MIT
CCF2017 MIT 2019-7-2
编辑：CCF2017 MIT 2019-7-2
i dont want to be arguing about what is efficient and what is not, and which one is complicated. what i certainly dont agree with is having an answer and not explaning properly. literally everyone in the comments section is asking for the meaning of your answer, yet you dont want to ellaborate further.
i am a beginner in matlab programming and so are many others, you must understand that not everyone has access to the best resources and not everyone has the knowledge or the skill that you have acquired . Hence you must try and be a little more specific and not take it for granted that someone knows. because it can be easy for you, and it can be complicated for others.
Guillaume
Guillaume 2019-7-2
I have explained how to do it in various comments here. I'm not sure how I can explain it more without giving the solution away.
In one comment, I wrote that all that is needed is: "a subtraction by an integer, a mod, an addition by the same integer" (and a conversion to char afterwards).
You have a message with a set of numbers (characters) between two values a and b. Shift that set of numbers so that it is between 0 and b-a. Add your caesar shift. This may underflow 0 or overflow b-a. Apply mod so that it wraps back between 0 and b-a. Reverse your original shift so that the numbers are once agian between a and b.

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Rahul Gulia
Rahul Gulia 2019-7-22
编辑：Guillaume 2019-7-22
function coded = caesar(str,n)
num1 = double(str); %Converting string to double to make the defined shifts
for i = 1 : length(num1)
if num1(i) + n > 126 % If ASCII value goes beyond 126
m = num1(i)-126+n;
p = 31+m;
num1(i) = p;
elseif num1(i)+n < 32 % If ASCII value goes below 32
m = 32 - num1(i) + n;
p = 126 - m;
num1(i) = p;
else m = num1(i) + n; % In a normal condition
num1(i) = m;
end
code(i) = num1(i);
end
coded = char(code);
I have written this code. Can anyone please expain as what is wrong in here? I know i have made a mistake. But i am not able to figure it out.
Thanks in advance.
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Walter Roberson
Walter Roberson 2020-7-12
Suppose n = 1000 and the character vector is 'a' (which is 97 decimal). num1 would become 97. num1(1)+1000 > 126, so m = 97-126+1000 would be m=971. Then p=31+971 gives p = 1002 . This is not the desired result.
The code needs to adjust num1+n to be between 32 and 126 (inclusive)

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shreyansh pitroda
shreyansh pitroda 2020-3-30
%% Function encode the code by shifting it by amount user as specified
function [coded]= caesar(code , shift) %% TAKES TWO VALUE CODE AND AMOUNT OF SHIFT
A = double(code);
x = 1;
z = length(A);
z = z+ 1;
shift = shift - 95*(fix(shift/95));
code(1:end) = code(1:end) + shift;
while x ~= z %%used the while loop to provide count
if code(1,x)< 32 %%if the value is below 32
A(1,x) = A(1,x) - 32;
A(1,x) = A(1,x) + shift;
A(1,x) = A(1,x) + 127;
elseif (code(1,x)>32)&&(code(1,x)<127) %% if value is between 32 and 127
A(1,x) = A(1,x) + shift;
else %% if the value is greater than 127
A(1,x) = A(1,x) - 127;
A(1,x) = A(1,x) + shift;
A(1,x) = A(1,x) + 32;
end
x= x + 1;
end
coded = char(A); %% code print
end
Washida Kami
Washida Kami 2020-3-31
%uses the mod function
function txt = caesar(txt,key)
txt = double(txt) + key;
first = double(' ');
last = double('~');
% use mod to shift the characters - notice the + 1
% this is a common error and results in shifts
% being off by 1
txt = char(mod(txt - first,last - first + 1) + first);
end
%uses the circshift function
function y = caesar2(ch, key)
v = ' ' : '~';
[~, loc] = ismember(ch, v);
v2 = circshift(v, -key);
y = v2(loc);
end
  2 个评论
Noor Ul Zain
Noor Ul Zain 2020-8-20
can someone please explain the mod function code, I also dont get why we add first, shouldnt we add first-1. Please please explain
Walter Roberson
Walter Roberson 2020-8-20
Suppose txt == first, then txt-first is 0, and mod(0,something) is 0. Now suppose you had the first-1 that you propose, then the result would be first-1 . Clearly, though, it makes the most sense for the calculation to leave you within the first to last range, instead of before the range.

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Rajat Munjal
Rajat Munjal 2020-4-13
编辑：DGM 2023-2-26
function coded = caesar(ctbe,sa)
dd = double(ctbe)
if dd>=32 & dd<=126
ss =dd +sa
ss(ss<32) = rem((ss(ss<32)-32),95)+127
ss(ss>126)=rem((ss(ss>126)-126),95)+31
coded =char(ss);
end
end
  2 个评论
Rajat Munjal
Rajat Munjal 2020-4-13
Can someone please help me in finding the mistake ?
Walter Roberson
Walter Roberson 2020-4-13
dd = double(ctbe)
ctbe will be a vector of char, so dd will be a vector of double.
if dd>=32 & dd<=126
dd>=32 & dd<=126 would be a logical vector. When you test a non-scalar with if or while, it is considered true if all of the items being tested are non-zero (true). If even one of the entries was not within that range then the test would be considered false as a whole... and you have no else condition so nothing would be assigned to coded

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Olel Arem
Olel Arem 2020-4-30
编辑：Olel Arem 2020-4-30
Short code with use of Logical Indexing:
function coded= caesar(string,shift)
mod_str=string+shift;
for i=1:length(mod_str)
mod_str(mod_str<32)=mod_str(mod_str<32)+95;
mod_str(mod_str>126)=mod_str(mod_str>126)-95;
end
coded=char(mod_str);
Omkar Kadam
Omkar Kadam 2020-5-9
function coded = caesar(V,N)
ascii = char(32:126);
coded1 = (double(V) + N - 31);
found = false;
ii = 1;
coded2 = [];
while ~(found)
if ii < length(coded1)+1
j = coded1(ii);
ii = ii +1;
while j < 32
j = j + 126 - 31;
end
while j > length(ascii)
j = j - length(ascii);
end
coded2 = abs([coded2,j]);
else
found = true;
break;
end
end
coded = ascii(coded2); %this is 100% working code.
GAURAV RAJ
GAURAV RAJ 2020-5-10
help me in this . i wrote this code but i am getting error please tell me what's wrong in this
function y=caesar(a,b)
q=double(a);
for i=1:length(a)
d(i)=q(i)+b;
if d(i)>=32;
e(i)=rem(d(i),126);
else
e(i)=95+d(i);
end
if e(i)>=32 ;
y(i)=char(e(i));
elseif e(i)==0;
y(i)=char(126);
else
e(i)=e(i)+31;
y(i)=char(e(i));
end
end
end
  1 个评论
Walter Roberson
Walter Roberson 2020-5-11
Suppose b is -200 and q is double('A') = 65.
d = 65-200 -> d = -135
-135 >= 32 is false, so
e = 95 + -135 = -40
-40 >= 32 is false
-40 == 0 is false
e(i) = -40 + 31 = -9
y(i) = char(-9) which is same as char(0)

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Arafat Roney
Arafat Roney 2020-5-11
function coded=caesar(c,s)
n=mod(s,95);
sc=c+n;
l=length(sc);
w=[];
for i=1:l
if sc(i)>126
p=31+(sc(i)-126);
elseif sc(i)<32
p=126-abs(sc(i)-31);
else
p=sc(i);
end
w=[w p];
end
coded=char(w);
end
Shandilya Kiran Bhatt
编辑：Walter Roberson 2020-5-12
The code below is a long one but it is using a while loop and if you read it, it is an easy one and it is correct for any random shifts.
function coded = caesar(A,n)
a = double(A);
z = a + n;
for i =1: length(a)
if z(i)>126
b = z(i) - 126;
if b <=95
z(i) = 31 + b;
else
while b > 95
b = b-95;
end
z(i) = 31 + b;
end
end
if z(i) < 32
c = 32 - z(i);
if c <= 95
z(i) = 127 - c;
else
while c >95
c = c - 95;
end
z(i) = 127 -c;
end
end
end
encrypted_code = z;
coded = char(encrypted_code);
end
SAMARTH MAHESHKUMAR GEMLAWALA
This code is quite lenghty, but logic that i have used is quite simple understand
function coded = caesar(A, n)
a = double(A)
ele=size(a)
for i=1:ele(1,2)
if n>=0
for j=1:n
a(i) = a(i)+1;
if a(i)>126
a(i)=32;
end
end
end
if n<0
for j=1:abs(n)
a(i) = a(i)-1;
if a(i)<32
a(i)=126;
end
end
end
end
coded = char(a);
end
Julian Veran
Julian Veran 2020-5-18
function coded = caesar(M, n)
num = double(M); %Converts string into double
num2 = num;
N = n - 95 * fix(n/95);
for i = 1:length(num);
if num(i) + N < 32 %If ASCII value goes below 32
num2(i) = 126 - (31- num(i) - N);
elseif num(i) + N > 126 %If ASCII value goes beyond 126
num2(i) = 32 + (num(i) + N -127);
else
num2(i) = num(i) + N ; %If ASCII value goes normal
end
coded = char(num2);
end
  1 个评论
Tatiana Suaza Varela
Tatiana Suaza Varela 2020-12-19
Hi! Sorry for the inconveniences, but please could you explain why we need to convert the string into double?

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Julian Veran
Julian Veran 2020-5-18
(using mod function)
function txt = caesar(txt,key)
txt = double(txt) + key;
first = double(' ');
last = double('~');
% use mod to shift the characters - notice the + 1
% this is a common error and results in shifts
% being off by 1
txt = char(mod(txt - first,last - first + 1) + first);
end
(using circ shify function)
function y = caesar2(ch, key)
v = ' ' : '~';
[~, loc] = ismember(ch, v);
v2 = circshift(v, -key);
y = v2(loc);
end
  2 个评论
Shenaz Fathima
Shenaz Fathima 2020-8-15
I dont get the last line of ur code.. Can u explain it? (using mod function) What is the function of mod?
Rik
Rik 2020-8-15
Have you read the documentation for the mod function?
doc mod

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Timothy Simon Thomas
%% CAESAR's SIPHER
% CAESAR(message,code): Message is the message to be encripted
% CODE represents the ASCII shift
% Wrapping always enabled
function coded = caesar(message,code)
while(code>95)
code=code-95;
end
while(code<-95)
code=code+95;
end
message=message+code; %base case
message(message>126)=char(double(message(message>126))-95) %overshoot
message(message<32)=char(double(message(message<32))+95) %undershoot
coded=char(message);
end
Taif Ahmed BIpul
Taif Ahmed BIpul 2020-5-21
编辑：DGM 2023-2-26
function coded=caesar(v,n)
x=double(v)+n;
q=x(x<32);
p=x(x>126);
while q<32;
x(x<32)=x(x<32)+95;
q=x(x<32);
end
while p>126;
x(x>126)=x(x>126)-95;
p=x(x>126);
end
coded=char(x);
end
yazan ziyad
yazan ziyad 2020-5-29
编辑：DGM 2023-2-26
here you go
function [coded]=caesar(a,shift)
m=double(a)
codedd=m+shift;
for i=1:abs(shift)
codedd(codedd<32)=127-(32-codedd(codedd<32));
codedd(codedd>126)=31+(codedd(codedd>126)-126)
coded=char(codedd)
end
end
SONU NIGAM
SONU NIGAM 2020-5-29
function coded = caesar(char_vec,shift_amount)
char_value = char_vec+shift_amount;
for ii = 1:length(char_value)
if char_value>126
coded = char(char_value-95);
elseif char_value<32
coded = char(char_value+95);
else
coded = char(char_value);
end
end
end
I got correct output but in the assignment when i run this program it shows error...What fault i did i m unable to notice,if anyone can explain me then plz help me.
Soroush sa
Soroush sa 2020-5-30
编辑：DGM 2023-2-26
I'm beginner and I have written this code. Can anybody help me by expaining that what is wrong in here?
function coded = caesar(string,shift)
double_A = double(string);
position = double_A + shift;
for ii = 1:length(position)
if position > 126
new_position = position - 95;
elseif position < 32
new_position = position + 95;
else
new_position = position;
end
end
coded = char(new_position);
end
Sumit Kumar Sharma
function coded=caesar(a,b)
x=double(a);
k=mod(b,95);
q=[];
for j=1:length(x)
p=x(j)+k;
if p<=126 && p>=32
q=[q p];
elseif p>126
r=p-95;
q=[q r] ;
elseif p<32
s=p+95;
q=[q s];
end
end
coded=char(q);
end
Vistasp Edulji
Vistasp Edulji 2020-6-22
A much shorter solution is possible using logical arrays.
function coded =caesar(str, n)
coded = str + n;
while ( sum(coded >= 127) > 0 || sum(coded <= 31) >0 )
coded(coded >= 127) = 31 + (coded(coded>=127)-126);
coded(coded <= 31) = 127 - (32-coded(coded<=31));
end
coded = char(coded);
The while loop condition simply ensures that there is no overflow after each round of correction
The important thing is your output should be a string
Alankriti Mallick
Alankriti Mallick 2020-7-26
function coded= caesar(v,s)
v=v+s;
v(v>126)=rem(v(v>126),95);
v(v<32)=127-rem(32-v(v<32),95);
coded=char(v);
Ankit singh chauhan
编辑：DGM 2023-2-26
function cloud=caesar(m,n)
sum=double(m+n);
for i=1:length(sum)
if n>0
if (sum(i)<127)
cloud(i)=char(sum(i));
elseif sum(i)>126
store=sum(i)-126;
sto=mod(store,95);
if sto==0
s=126;
cloud(i)=char(s+sto);
else
s=32;
cloud(i)=char(s+sto-1);
end
end
else
if n<0
if (sum(i)>=32)
cloud(i)=char(sum(i));
else
if sum(i)<32
store=32-sum(i);
sto=mod(store,95);
cloud(i)=char(126-sto+1);
end
end
end
end
end
end
Juan Sebastián Hincapié Montes
编辑：Juan Sebastián Hincapié Montes 2020-8-21
function [coded] = caesar(v ,sa)
secret = double(v);
code = ones(1, length(v));
for ii=1:length(secret)
if secret(ii)+sa > 126 %greater than 126
remainder=rem(sa,95);
if remainder + secret(ii)>126 %if the double plus the remainder is greater than 32
code(ii)=31+(remainder-(126-secret(ii)));
else
code(ii)=remainder+secret(ii); %if the double plus the remainder isn't greater than 32
end
elseif secret(ii)+sa < 32 %lower than 32
remainder=abs(rem(sa,95));
if secret(ii)-remainder < 32 %if the double plus the remainder is lower than 32
code(ii)=127-(remainder-(secret(ii)-32));
else
code(ii)=secret(ii)-remainder; %if the double plus the remainder isn't lower than 32
end
else
code(ii) = sa + secret(ii); %everything is normal
end
end
coded=char(code);
end
Mati Somp
Mati Somp 2020-10-5
simple and fast
function coded = caesar(txt,nr)
char_set=char(32):char(126);
char_set3=[char_set char_set char_set];
coded = char_set3(txt+64+nr-floor(nr/95)*95);
end
  4 个评论
显示 2更早的评论
Rik
Rik 2020-10-6
I would say using mod is a considerably simpler setup. What would you consider a ready-made function?
I have not run any performance test comparing the other solutions in this thread. Have you?
Walter Roberson
Walter Roberson 2020-10-6
Addition and subtraction and division and floor and concatenation and array indexing and char and the colon operator, are all readymade functions.
https://www.mathworks.com/matlabcentral/answers/38787-what-can-be-programmed-without-any-built-in-functions?s_tid=srchtitle

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Dhinesh Kumar
Dhinesh Kumar 2020-10-11
function txt = caesar(txt,key)
txt = double(txt) + key;
first = double(' ');
last = double('~');
% use mod to shift the characters - notice the + 1
% this is a common error and results in shifts
% being off by 1
txt = char(mod(txt - first,last - first + 1) + first);
end
This also helps to solve the problem. Try it
XINYI CAI
XINYI CAI 2021-3-15
Can someone help to explain how the ismember function work in this provided solution? Why it returns double instead of strings? Thanks in advance.
  2 个评论
Walter Roberson
Walter Roberson 2021-3-15
Ran in:
v = char(32):char(126);
ch = 'hello';
[~, loc] = ismember(ch, v);
v1 = circshift(v, -7);
class(v1)
ans = 'char'
v1(loc)
ans = 'olssv'
ch = [65 41 83]
ch = 1×3
65 41 83
char(ch)
ans = 'A)S'
[~, loc] = ismember(ch, v);
v1 = circshift(v, -7);
v1(loc)
ans = 'H0Z'
Looks okay to me, no matter whether you input numeric or text values.
The second output of ismember() is defined as indices, and would never be expected to be characters. For example,
v = blanks(100000);
v(end) = 'A';
[found, idx] = ismember('A', v)
found = logical
1
idx = 100000
It would not make sense for the second output (position) to return a character, as characters have maximum numeric equivalent of 65535.

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Raghav Arvind Thirumurugan
编辑：Walter Roberson 2022-3-21
function coded=caesar(c,n)
x=double(c);
l=length(x);
for b=1:l
x(b)=x(b)+n;
end
for a=1:l
while x(a)<32 || x(a)>126
if x(a)<32
x(a)=x(a)+95;
else x(a)>126
x(a)=x(a)-95;
end
end
end
coded=char(x);
end
Selman Baysal
Selman Baysal 2022-1-2
I am agree with @Wilver Sánchez's solution. I highly recommend avoiding to use "for loop" (it is not the wrong way, but it sometimes increases the processing time; maybe not for this code).
% instead of using
for ii = 1:length(unicodeMessage)
if secret(ii) < 32
....
end
end
% more sophisticated way
secret(secret < 32) = ....
Then, my solution is that:
function coded = caesar(M,s)
% for other types of code, values of highest and lowest can be changed.
highest = 126; % max ASCII code
lowest = 32; % min ASCII code
codes = highest - lowest + 1; % number of codes in ASCII
n = fix(s/(codes)); % how many times the code will be wrapped
res = s - codes*n; % how much the code will be shifted (res: residual)
unicodeMessage = double(M);
secret = unicodeMessage + res;
secret(secret < 32) = 126 - (31 - secret(secret < 32));
secret(secret > 126) = 32 + (secret(secret > 126) - 127);
coded = char(secret);
end
Lokeswar Reddy
Lokeswar Reddy 2022-7-10
编辑：DGM 2023-2-26
function out = caesar(m,n)
m = double(m)+n;
m = mod(m,95);
m(m>126) = m(m>126)-126 +31;
m(m<32) = m(m<32) -32+127;
out = char(m);
end
Muhammad
Muhammad 2022-8-1
%Help required
function coded = caesar(X,Y)
X=char(X);
code=double(X)+Y;
if code>=126
code=code-95;
coded=fprintf('%s',code);
elseif code<=32
code=code+95;
coded=fprintf('%s',code);
else
code=double(X)+Y;
coded=fprintf('%s',code);
end
  5 个评论
显示 3更早的评论
Muhammad
Muhammad 2022-8-1
function coded = caesar(X,Y)
X=char(X);
code=double(X)+Y;
if code>126
code=code-95;
coded=char('%s',code);
elseif code<32
code=code+95;
coded=char('%s',code);
else
code=double(X)+Y;
coded=char('%s',code);
end

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Zia Ur Rehman
Zia Ur Rehman 2022-8-28
Hi folks,
I write this code, this is working fine with the problem.
Need further improvement if any from seniors as I'm very novice in coding and MATLAB. It took almost 90 minutes to solve.
function coded = caesar(a,b)
% removing the ';' so you can see how it works in output
c = double(a) % to convert the given char(string) into double(numeric)
d=c+b % adding the shift smount to encrypt
l= length(d) % measuring the length as we need to traverse every element to check if it lies in the limit(32:126)
for e = 1:l % applying loop to check each element if it lies in the limit
while d(e) > 126 % using while as if we use 'if' statement it will only execute once but we need execution untill the value comes in the limit
d(e) = d(e)-95 % if number is greater than 126 so wrap around by adding (126-32+1=95) we use +1 as we need next number not the same number
end
while d(e) < 32 % using while as if we use if statement it will only execute once but we need execution untill the value comes in the limit
d(e) = d(e) + 95 % if number is less than 32 so wrap around by subtracting (126-32+1=95) we use +1 as we need next number not the same number
end
end
coded=char(d) % d is now updated according to the limit
%coded = char(double(a) + b)
end
昱安 朱
昱安 朱 2023-3-10
编辑：DGM 2023-3-18
function [coded]=caesar(encrypt,shift)
coded_num=encrypt+shift;
big=coded_num(coded_num>126);
small=coded_num(coded_num<32);
coded_num(coded_num>126)=big-95*fix((big-32)/95);
coded_num(coded_num<32)=small-95*fix((small-32)/95-1);
coded=char(coded_num);
end
Muhammad Saleh
Muhammad Saleh 2023-10-30
function coded=caesar(v, shift)
if(shift>94)
shift=mod(shift,94);
end
if (shift<-94)
shift=-(mod(abs(shift),94));
end
%%if the string has strange input
if(max(double(v))>126 || min(double(v))<32)
fprintf("Error in the string");
coded=[];
return
end
%%if shifting does not voilate the range
if((max(double(v))+shift)<=126 && (min(double(v))+shift)>=32)
coded=char(double(v)+shift);
return
end
tempo=double(v);
for ii=1:strlength(v)
%% if shifting doesnot voilate the range
if(((tempo(1,ii)+shift)<=126) && (tempo(1,ii)+shift)>=32)
tempo(1,ii)=tempo(1,ii)+shift;
end
%% if shifting voilate the upper range
if((tempo(1,ii)+shift)>126)
tempo(1,ii)=mod(tempo(1,ii)+shift,127)+32;
end
%% if shifting voilate the lower range
if((tempo(1,ii)+shift)<32)
tempo(1,ii)=127+(mod(tempo(1,ii)+shift,32)-32);
end
end
coded=char(tempo);
end
Karel Octavianus Bachri
Karel Octavianus Bachri 2024-4-13，0:53
编辑：Karel Octavianus Bachri 2024-4-13，1:27
finally solved,
function coded = caesar(mytext,shift)
tempshift=shift
%limit the shift from 0 to 95
while tempshift > 95
tempshift = tempshift - 95;
end
%limit the shift from -95 to 0
while tempshift < -95
tempshift = tempshift + 95;
end
tempcoded=zeros(1,length(mytext))
%shifting
tempcoded=mytext+tempshift
%wrapping using indexing
tempcoded(1,tempcoded>126)=tempcoded(1,tempcoded>126)-95
tempcoded(1,tempcoded<32)=tempcoded(tempcoded<32)+95
coded=char(tempcoded)
end

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