I have inherited some legacy vb6 code. It's a tool which generates a local admin password for a windows pc. The password is supposed to contain only a limited set of characters. The tool works fine.. as long as it's not run on chinese or russian PCs. There, it generates weird passwords that nobody can type in. Of course it has something to do with the current operating system culture. The Chr(CharCode) function returns some weird characters on those systems. Anyone has a clue on how to make this culture invariant? I only want the tool to generate passwords with standard ASCII characters.
Function generatePassword(PASSWORD_LENGTH)
Dim NUMLOWER, NUMUPPER, LOWERBOUND, UPPERBOUND, LOWERBOUND1, UPPERBOUND1, SYMLOWER, SYMUPPER
Dim newPassword, count, pwd
Dim pCheckComplex, pCheckComplexUp, pCheckComplexLow, pCheckComplexNum, pCheckComplexSym, pCheckAnswer
NUMLOWER = 48 ' 48 = 0
NUMUPPER = 57 ' 57 = 9
LOWERBOUND = 65 ' 65 = A
UPPERBOUND = 90 ' 90 = Z
LOWERBOUND1 = 97 ' 97 = a
UPPERBOUND1 = 122 ' 122 = z
SYMLOWER = 33 ' 33 = !
SYMUPPER = 46 ' 46 = .
pCheckComplexUp = 0 ' used later to check number of character types in password
pCheckComplexLow = 0 ' used later to check number of character types in password
pCheckComplexNum = 0 ' used later to check number of character types in password
pCheckComplexSym = 0 ' used later to check number of character types in password
' initialize the random number generator
Randomize
newPassword = ""
count = 0
Do Until count = PASSWORD_LENGTH
' generate a num between 2 and 10
' if num <= 2 create a symbol
If Int((10 - 2 + 1) * Rnd + 2) <= 2 Then
'pwd = Int( ( SYMUPPER - SYMLOWER + 1 ) * Rnd + SYMLOWER )
pwd = Int((UPPERBOUND1 - LOWERBOUND1 + 1) * Rnd + LOWERBOUND1)
' if num is between 3 and 5 create a lowercase
ElseIf Int((10 - 2 + 1) * Rnd + 2) > 2 And Int((10 - 2 + 1) * Rnd + 2) <= 5 Then
pwd = Int((UPPERBOUND1 - LOWERBOUND1 + 1) * Rnd + LOWERBOUND1)
' if num is 6 or 7 generate an uppercase
ElseIf Int((10 - 2 + 1) * Rnd + 2) > 5 And Int((10 - 2 + 1) * Rnd + 2) <= 7 Then
pwd = Int((UPPERBOUND - LOWERBOUND + 1) * Rnd + LOWERBOUND)
Else
pwd = Int((NUMUPPER - NUMLOWER + 1) * Rnd + NUMLOWER)
End If
If Chr(pwd) <> "l" And Chr(pwd) <> "I" Then
newPassword = newPassword + Chr(pwd)
count = count + 1
End If
'Check to make sure that a proper mix of characters has been created. If not discard the password.
If count = (PASSWORD_LENGTH) Then
For pCheckComplex = 1 To PASSWORD_LENGTH
'Check for uppercase
If Asc(Mid(newPassword, pCheckComplex, 1)) > 64 And Asc(Mid(newPassword, pCheckComplex, 1)) < 90 Then
pCheckComplexUp = 1
'Check for lowercase
ElseIf Asc(Mid(newPassword, pCheckComplex, 1)) > 96 And Asc(Mid(newPassword, pCheckComplex, 1)) < 123 Then
pCheckComplexLow = 1
'Check for numbers
ElseIf Asc(Mid(newPassword, pCheckComplex, 1)) > 47 And Asc(Mid(newPassword, pCheckComplex, 1)) < 58 Then
pCheckComplexNum = 1
'Check for symbols
ElseIf Asc(Mid(newPassword, pCheckComplex, 1)) > 32 And Asc(Mid(newPassword, pCheckComplex, 1)) < 47 Then
pCheckComplexSym = 1
End If
Next
'Add up the number of character sets. We require 3 or 4 for a complex password.
pCheckAnswer = pCheckComplexUp + pCheckComplexLow + pCheckComplexNum + pCheckComplexSym
If pCheckAnswer < 3 Then
newPassword = ""
count = 0
End If
End If
Loop
'The password is good so return it
generatePassword = newPassword
End Function
Deanna's comment is correct. Just change Chr to ChrW and change Asc to AscW.
ChrW accepts Unicode code points
Chr accepts "ANSI" code points, and the meaning of a particular code point will be different depending on the system code page. For example on Chinese and Russian code pages.
As Russian and Chinese PCs (and many others) do not operate with an ASCII character set but culture specific UNICODE then I am not surprised that your password program generates a password that cannot be typed in by the user.
You'll only achieve success by moving away from ASCII.
There are a number of open source password generators available online. If you can find one with source code then you'll be quids in , so to speak.
Related
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.
My task is to write a function that:
accepts two arguments: the first is the character vector to be encrypted, and the second is the shift amount.
returns one output, which is the encrypted text.
needs to work with all the visible ASCII characters from space to ~ (ASCII codes of 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 ~.
This is my MATLAB code:
function [coded] = caesar(input_text, shift)
x = double(input_text); %converts char symbols to double format
for ii = 1:length(x) %go through each element
if (x(ii) + shift > 126) & (mod(x(ii) + shift, 127) < 32)
x(ii) = mod(x(ii) + shift, 127) + 32; %if the symbol + shift > 126, I make it 32
elseif (x(ii) + shift > 126) & (mod(x(ii) + shift, 127) >= 32)
x(ii) = mod(x(ii) + shift, 127);
elseif (x(ii) + shift < 32) & (126 + (x(ii) + shift - 32 + 1) >= 32)
x(ii) = 126 + (x(ii) + shift - 32 + 1);
elseif (x(ii) + shift < 32) & (126 + (x(ii) + shift - 32 + 1) < 32)
x(ii) = abs(x(ii) - 32 + shift - 32);
else x(ii) = x(ii) + shift;
end
end
coded = char(x); % converts double format back to char
end
I can't seem to make the wrapping conversions correctly (e.g. from 31 to 126, 30 to 125, 127 to 32, and so on). How should I change my code to do that?
Before you even start coding something like this, you should have a firm grasp of how to approach the problem.
The main obstacle you encountered is how to apply the modulus operation to your data, seeing how mod "wraps" inputs to the range of [0 modPeriod-1], while your own data is in the range [32 126]. To make mod useful in this case we perform an intermediate step of shifting of the input to the range that mod "likes", i.e. from some [minVal maxVal] to [0 modPeriod-1].
So we need to find two things: the size of the required shift, and the size of the period of the mod. The first one is easy, since this is just -minVal, which is the negative of the ASCII value of the first character, which is space (written as ' ' in MATLAB). As for the period of the mod, this is just the size of your "alphabet", which happens to be "1 larger than the maximum value, after shifting", or in other words - maxVal-minVal+1. Essentially, what we're doing is the following
input -> shift to 0-based ("mod") domain -> apply mod() -> shift back -> output
Now take a look how this can be written using MATLAB's vectorized notation:
function [coded] = caesar(input_text, shift)
FIRST_PRINTABLE = ' ';
LAST_PRINTABLE = '~';
N_PRINTABLE_CHARS = LAST_PRINTABLE - FIRST_PRINTABLE + 1;
coded = char(mod(input_text - FIRST_PRINTABLE + shift, N_PRINTABLE_CHARS) + FIRST_PRINTABLE);
Here are some tests:
>> caesar('blabla', 1)
ans =
'cmbcmb'
>> caesar('cmbcmb', -1)
ans =
'blabla'
>> caesar('blabla', 1000)
ans =
'5?45?4'
>> caesar('5?45?4', -1000)
ans =
'blabla'
We can solve it using the idea of periodic functions :
periodic function repeats itself every cycle and every cycle is equal to 2π ...
like periodic functions ,we have a function that repeats itself every 95 values
the cycle = 126-32+1 ;
we add one because the '32' is also in the cycle ...
So if the value of the character exceeds '126' we subtract 95 ,
i.e. if the value =127(bigger than 126) then it is equivalent to
127-95=32 .
&if the value is less than 32 we subtract 95.
i.e. if the value= 31 (less than 32) then it is equivalent to 31+95
=126..
Now we will translate that into codes :
function out= 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
out=char(value);
First i converted the output(shift+ text_input) to char.
function coded= caesar(text_input,shift)
coded=char(text_input+shift);
for i=1:length(coded)
while coded(i)<32
coded(i)=coded(i)+95;
end
while coded(i)>126
coded(i)=coded(i)-95;
end
end
Here Is one short code:
function coded = caesar(v,n)
C = 32:126;
v = double(v);
for i = 1:length(v)
x = find(C==v(i));
C = circshift(C,-n);
v(i) = C(x);
C = 32:126;
end
coded = char(v);
end
I want to take a number and convert it into lowercase a-z letters using VBScript.
For example:
1 converts to a
2 converts to b
27 converts to aa
28 converts to ab
and so on...
In particular I am having trouble converting numbers after 26 when converting to 2 letter cell names. (aa, ab, ac, etc.)
You should have a look at the Chr(n) function.
This would fit your needs from a to z:
wscript.echo Chr(number+96)
To represent multiple letters for numbers, (like excel would do it) you'll have to check your number for ranges and use the Mod operator for modulo.
EDIT:
There is a fast food Copy&Paste example on the web: How to convert Excel column numbers into alphabetical characters
Quoted example from microsoft:
For example: The column number is 30.
The column number is divided by 27: 30 / 27 = 1.1111, rounded down by the Int function to "1".
i = 1
Next Column number - (i * 26) = 30 -(1 * 26) = 30 - 26 = 4.
j = 4
Convert the values to alphabetical characters separately,
i = 1 = "A"
j = 4 = "D"
Combined together, they form the column designator "AD".
And its code:
Function ConvertToLetter(iCol As Integer) As String
Dim iAlpha As Integer
Dim iRemainder As Integer
iAlpha = Int(iCol / 27)
iRemainder = iCol - (iAlpha * 26)
If iAlpha > 0 Then
ConvertToLetter = Chr(iAlpha + 64)
End If
If iRemainder > 0 Then
ConvertToLetter = ConvertToLetter & Chr(iRemainder + 64)
End If
End Function
Neither of the solutions above work for the full Excel range from A to XFD. The first example only works up to ZZ. The second example has boundry problems explained in the code comments below.
//
Function ColumnNumberToLetter(ColumnNumber As Integer) As String
' convert a column number to the Excel letter representation
Dim Div As Double
Dim iMostSignificant As Integer
Dim iLeastSignificant As Integer
Dim Base As Integer
Base = 26
' Column letters are base 26 starting at A=1 and ending at Z=26
' For base 26 math to work we need to adjust the input value to
' base 26 starting at 0
Div = (ColumnNumber - 1) / Base
iMostSignificant = Int(Div)
' The addition of 1 is needed to restore the 0 to 25 result value to
' align with A to Z
iLeastSignificant = 1 + (Div - iMostSignificant) * Base
' convert number to letter
ColumnNumberToLetter = Chr(64 + iLeastSignificant)
' if the input number is larger than the base then the conversion we
' just did is the least significant letter
' Call the function again with the remaining most significant letters
If ColumnNumber > Base Then
ColumnNumberToLetter = ColumnNumberToLetter(iMostSignificant) & ColumnNumberToLetter
End If
End Function
//
try this
function converts(n)
Dim i, c, m
i = n
c = ""
While i > 26
m = (i mod 26)
c = Chr(m+96) & c
i = (i - m) / 26
Wend
c = Chr(i+96) & c
converts = c
end function
WScript.Echo converts(1000)
I need to generate repeatable pseudo random numbers based on a set of coordinates, so that with a given seed, I will always generate the same value for a specific coordinate.
I figured I'd use something like this for the seed:
/* 64bit seed value*/
struct seed_cord {
uint16 seed;
uint16 coord_x_int;
uint16 coord_y_int;
uint8 coord_x_frac;
uint8 coord_y_frac;
}
Where coord_x_int is the integer part of the coordinate, and the fraction part is given by coord_x_frac / 0xFF. seed is a randomly pre-determined value.
But I must admit, trying to understand all the intricacies of PRNGs is a little overwhelming. What would be a good generator for what I'm attempting?
I tested out Java's PRNG using using this scheme in a quick groovy script, with the following result:
Obviously, this is hardly decent randomness.
The script I used was:
import java.awt.image.BufferedImage
import javax.imageio.ImageIO
short shortSeed = new Random().next(16) as short
def image = new BufferedImage(512, 512, BufferedImage.TYPE_BYTE_GRAY)
def raster = image.getRaster()
//x
(0..1).each{ x ->
(0..255).each{ xFrac ->
//y
(0..1).each{ y ->
(0..255).each{ yFrac ->
long seed = (shortSeed as long) << 48 |
(x as long) << 32 |
(y as long) << 16 |
(xFrac as long) << 8 |
(yFrac as long)
def value = new Random(seed).next(8)
raster.setSample( (x? xFrac+256 : xFrac), (y? yFrac+256 : yFrac), 0 , value)
}}}}
ImageIO.write(image, "PNG", new File("randomCoord.png"))
If you're really only looking at 512x512, then that's uh... 218 pixels you're interested in.
There's plenty of space for that kind of population with good ole MD5 (128 bit output).
You can just take the lowest 32 bits for an integer if that's the kind of output you need. Really, any sort of hashing algorithm that has an output space at least as large as an int will do.
Now, you can do all sorts of fun stuff if you're paranoid. Start with a hash of your coordinates, then feed the result into a secure random number generator (java.security.SecureRandom). Then hash it 1000 times with a salt that's your birthday concatenated (x+y) times.
Joking aside, random number generators don't necessarily have wildly varying results based on small variations of the seed. They're designed to have a really, super duper long chain of generated numbers before they start repeating, while having those chains pretty evenly distributed among the number space.
On the other hand, the SecureRandom is designed to have the additional feature of being chaotic in regard to the seed.
Most languages have a PRNG package (or two) that lets you initialize the generator with a specific seed. PRNGs can also often be found as part of a larger cryptographic package; they tend to be a bit stronger than those found in general-purpose libraries.
I would take a program like this one I have created and then modify it to pick coordinates:
REM $DYNAMIC
COMMON SHARED n%, rbuf%, sz%, sw%, p1$
DECLARE SUB initialize ()
DECLARE SUB filbuf ()
DECLARE SUB setup ()
DECLARE FUNCTION Drnd# ()
DECLARE SUB core ()
DECLARE SUB modify ()
DIM SHARED pad1(340) AS STRING * 1
DIM SHARED trnsltr(66) AS STRING * 1 ' translates a 0-67 value into a pad character
DIM SHARED trnslt(255) AS INTEGER 'translates a pad value to 0-67 value -1 if error
DIM SHARED moders(26) AS INTEGER 'modding function prim number array
DIM SHARED moders2(26) AS INTEGER 'modding function prim number array
DIM SHARED ranbuf(1 TO 42) AS DOUBLE 'random number buffer if this is full and rbuf %>0
REM then this buffer is used to get new random values
REM rbuf% holds the index of the next random number to be used
REM subroutine setup loads the prime number table
REM from the data statements to be used
REM as modifiers in two different ways (or more)
REM subroutine initialize primes the pad array with initial values
REM transfering the values from a string into an array then
REM makes the first initial scrambling of this array
REM initializing pad user input phase:
CLS
INPUT "full name of file to be encrypted"; nam1$
INPUT "full name of output file"; nam2$
INPUT "enter password"; p2$
rbuf% = 0
n% = 0: sw% = 0
p3$ = STRING$(341, "Y")
p1$ = "Tfwd+-$wiHEbeMN<wjUHEgwBEGwyIEGWYrg3uehrnnqbwurt+>Hdgefrywre"
p1$ = p2$ + p1$ + p3$
PRINT "hit any key to continue any time after a display and after the graphic display"
p1$ = LEFT$(p1$, 341)
sz% = LEN(p1$)
CALL setup
CALL initialize
CLS
ibfr$ = STRING$(512, 32)
postn& = 1
OPEN nam1$ FOR BINARY AS #1
OPEN nam2$ FOR BINARY AS #2
g& = LOF(1)
max& = g&
sbtrct% = 512
WHILE g& > 0
LOCATE 1, 1
PRINT INT(1000 * ((max& - g&) / max&)) / 10; "% done";
IF g& < 512 THEN
ibfr$ = STRING$(g&, 32)
sbtrct% = g&
END IF
GET #1, postn&, ibfr$
FOR ste% = 1 TO LEN(ibfr$)
geh% = INT(Drnd# * 256)
MID$(ibfr$, ste%, 1) = CHR$(geh% XOR ASC(MID$(ibfr$, ste%, 1)))
NEXT ste%
PUT #2, postn&, ibfr$
postn& = postn& + sbtrct%
g& = g& - sbtrct%
WEND
CLOSE #2
CLOSE #1
PRINT "hit any key to exit"
i$ = ""
WHILE i$ = "": i$ = INKEY$: WEND
SYSTEM
END
DATA 3,5,7,9,11,13,17,19
DATA 23,29,33,37,43,47
DATA 53,59,67,71,73,79,83
DATA 89,91,97,101,107,109
DATA 43,45,60,62,36
REM $STATIC
SUB core
REM shuffling algorythinm
FOR a% = 0 TO 339
m% = (a% + 340) MOD 341: bez% = trnslt(ASC(pad1(340)))
IF n% MOD 3 = 0 THEN pad1(340) = trnsltr((2 * trnslt(ASC(pad1(a%))) + 67 - trnslt(ASC(pad1(m%)))) MOD 67)
IF n% MOD 3 = 1 THEN pad1(340) = trnsltr((2 * (67 - trnslt(ASC(pad1(a%)))) + 67 - trnslt(ASC(pad1(m%)))) MOD 67)
IF n% MOD 3 = 2 THEN pad1(340) = trnsltr(((2 * trnslt(ASC(pad1(a%))) + 67 - trnslt(ASC(pad1(m%)))) + moders(n% MOD 27)) MOD 67)
pad1(a% + 1) = pad1(m%): n% = (n% + 1) MOD 32767
pad1(a%) = trnsltr((bez% + trnslt(ASC(pad1(m%)))) MOD 67)
NEXT a%
sw% = (sw% + 1) MOD 32767
END SUB
FUNCTION Drnd#
IF rbuf% = 0 THEN
CALL core
CALL filbuf
IF sw% = 32767 THEN CALL modify
END IF
IF rbuf% > 0 THEN yut# = ranbuf(rbuf%)
rbuf% = rbuf% - 1
Drnd# = yut#
END FUNCTION
SUB filbuf
q% = 42: temp# = 0
WHILE q% > 0
FOR p% = 1 TO 42
k% = (p% - 1) * 8
FOR e% = k% TO k% + 7
temp# = temp# * 67: hug# = ABS(trnslt(ASC(pad1(e%)))): temp# = temp# + hug#
NEXT e%
IF temp# / (67 ^ 8) >= 0 AND q% < 43 THEN
ranbuf(q%) = temp# / (67 ^ 8): q% = q% - 1
END IF
temp# = 0
NEXT p%
WEND
rbuf% = 42
END SUB
SUB initialize
FOR a% = 0 TO 340
pad1(a%) = MID$(p1$, a% + 1, 1)
NEXT a%
FOR a% = 0 TO 340
LOCATE 1, 1
IF a% MOD 26 = 0 THEN PRINT INT((340 - a%) / 26)
sum% = 0
FOR b% = 0 TO 340
qn% = INT(Drnd# * 81)
op% = INT(qn% / 3)
qn% = qn% MOD 3
IF qn% = 0 THEN sum% = sum% + trnslt(ASC(pad1(b%)))
IF qn% = 1 THEN sum% = sum% + (67 + 66 - trnslt(ASC(pad1(b%)))) MOD 67
IF qn% = 2 THEN sum% = sum% + trnslt(ASC(pad1(b%))) + moders(op%)
NEXT b%
pad1(a%) = trnsltr(sum% MOD 67)
NEXT a%
n% = n% + 1
END SUB
SUB modify
REM modifier shuffling routine
q% = 26
temp# = 0
WHILE q% > -1
FOR p% = 1 TO 27
k% = (p% - 1) * 4 + 3
FOR e% = k% TO k% + 3
temp# = temp# * 67
hug# = ABS(trnslt(ASC(pad1(e%))))
temp# = temp# + hug#
NEXT e%
IF (temp# / (67 ^ 4)) >= 0 AND q% > -1 THEN
SWAP moders(q%), moders(INT(27 * (temp# / (67 ^ 4))))
q% = q% - 1
END IF
temp# = 0
NEXT p%
WEND
END SUB
SUB setup
FOR a% = 0 TO 26
READ moders(a%)
moders2(a%) = moders(a%)
NEXT a%
REM setting up tables and modder functions
FOR a% = 0 TO 25
trnsltr(a%) = CHR$(a% + 97)
trnsltr(a% + 26) = CHR$(a% + 65)
NEXT a%
FOR a% = 52 TO 61
trnsltr(a%) = CHR$(a% - 4)
NEXT a%
FOR a% = 62 TO 66
READ b%
trnsltr(a%) = CHR$(b%)
NEXT a%
FOR a% = 0 TO 255
trnslt(a%) = -1
NEXT a%
FOR a% = 0 TO 66
trnslt(ASC(trnsltr(a%))) = a%
NEXT a%
RESTORE
END SUB
the call to drand# gives you random numbers from 0 to 1 simply multiply that by your needed range for each vector needed p2$ is the password that is passed to the password handler which combines it with some other random characters and then caps the size to a certain limit p1$ is where the final modified password is contained
drand# itself calls another sub which is actually a clone of itself with some shuffling of
sorts that works to ensure that the numbers being produced are truly random there is also a table of values that are added in to the values being added all this in total makes the RNG many many more times random with than without.
this RNG has a very high sensitivity to slight differences in password initially set you must however make an intial call to setup and initialize to "bootstrap" the random number generator this RNG will produce Truly random numbers that will pass all tests of randomness
more random even then shuffling a deck of cards by hand , more random than rolling a dice..
hope this helps using the same password will result in the same sequnece of vectors
This program would have to be modified a bit though to pick random vectors rather than
it's current use as a secure encryption random number generator...
You can use encryption for this task, for example AES. Use your seed as the password, struct with coordinates as the data block and encrypt it. The encrypted block will be your random number (you can actually use any part of it). This approach is used in the Fortuna PRNG. The same approach can be used for disk encryption where random access of data is needed (see Random access encryption with AES In Counter mode using Fortuna PRNG:)
I want a function to calculate numerology.For example if i enter "XYZ" then my output should be 3 .
Here is how it became 3:
X = 24
Y = 25
Z = 26
on adding it becomes 75 which again adds up to 12 (7+5) which again adds up to 3(1+2) . Similarly whatever names i should pass,my output should be a single digit score.
Here you are:
Function Numerology(Str)
Dim sum, i, char
' Convert the string to upper case, so that 'X' = 'x'
Str = UCase(Str)
sum = 0
' For each character, ...
For i = 1 To Len(Str)
' Check if it's a letter and raise an exception otherwise
char = Mid(Str, i , 1)
If char < "A" Or char > "Z" Then Err.Raise 5 ' Invalid procedure call or argument
' Add the letter's index number to the sum
sum = sum + Asc(char) - 64
Next
' Calculate the result using the digital root formula (http://en.wikipedia.org/wiki/Digital_root)
Numerology = 1 + (sum - 1) Mod 9
End Function
In vbscript:
Function numerology(literal)
result = 0
for i = 1 to Len(literal)
'' // for each letter, take its ASCII value and substract 64,
'' so "A" becomes 1 and "Z" becomes 26
result = result + Asc(Mid(literal, i, 1)) - 64
next
'' // while result is bigger than 10, let's sum it's digits
while(result > 10)
partial = 0
for i = 1 to Len(CStr(result))
partial = partial + CInt(Mid(CStr(result), i, 1))
next
result = partial
wend
numerology = result
End Function
I have no idea what this could possible be used for but it was fun to write anyway.
Private Function CalcStupidNumber(ByVal s As String) As Integer
s = s.ToLower
If (s.Length = 1) Then 'End condition
Try
Return Integer.Parse(s)
Catch ex As Exception
Return 0
End Try
End If
'cover to Values
Dim x As Int32
Dim tot As Int32 = 0
For x = 0 To s.Length - 1 Step 1
Dim Val As Integer = ConvertToVal(s(x))
tot += Val
Next
Return CalcStupidNumber(tot.ToString())
End Function
Private Function ConvertToVal(ByVal c As Char) As Integer
If (Char.IsDigit(c)) Then
Return Integer.Parse(c)
End If
Return System.Convert.ToInt32(c) - 96 ' offest of a
End Function
This question already has answers here:
How to convert a column number (e.g. 127) into an Excel column (e.g. AA)
(60 answers)
Closed 9 years ago.
How would you determine the column name (e.g. "AQ" or "BH") of the nth column in Excel?
Edit: A language-agnostic algorithm to determine this is the main goal here.
I once wrote this function to perform that exact task:
public static string Column(int column)
{
column--;
if (column >= 0 && column < 26)
return ((char)('A' + column)).ToString();
else if (column > 25)
return Column(column / 26) + Column(column % 26 + 1);
else
throw new Exception("Invalid Column #" + (column + 1).ToString());
}
Here is the cleanest correct solution I could come up with (in Java, but feel free to use your favorite language):
String getNthColumnName(int n) {
String name = "";
while (n > 0) {
n--;
name = (char)('A' + n%26) + name;
n /= 26;
}
return name;
}
But please do let me know of if you find a mistake in this code, thank you.
A language agnostic algorithm would be as follows:
function getNthColumnName(int n) {
let curPower = 1
while curPower < n {
set curPower = curPower * 26
}
let result = ""
while n > 0 {
let temp = n / curPower
let result = result + char(temp)
set n = n - (curPower * temp)
set curPower = curPower / 26
}
return result
This algorithm also takes into account if Excel gets upgraded again to handle more than 16k columns. If you really wanted to go overboard, you could pass in an additional value and replace the instances of 26 with another number to accomodate alternate alphabets
Thanks, Joseph Sturtevant! Your code works perfectly - I needed it in vbscript, so figured I'd share my version:
Function ColumnLetter(ByVal intColumnNumber)
Dim sResult
intColumnNumber = intColumnNumber - 1
If (intColumnNumber >= 0 And intColumnNumber < 26) Then
sResult = Chr(65 + intColumnNumber)
ElseIf (intColumnNumber >= 26) Then
sResult = ColumnLetter(CLng(intColumnNumber \ 26)) _
& ColumnLetter(CLng(intColumnNumber Mod 26 + 1))
Else
err.Raise 8, "Column()", "Invalid Column #" & CStr(intColumnNumber + 1)
End If
ColumnLetter = sResult
End Function
Joseph's code is good but, if you don't want or need to use a VBA function, try this.
Assuming that the value of n is in cell A2
Use this function:
=MID(ADDRESS(1,A2),2,LEN(ADDRESS(1,A2))-3)
IF(COLUMN()>=26,CHAR(ROUND(COLUMN()/26,1)+64)&CHAR(MOD(COLUMN(),26)+64),CHAR(COLUMN()+64))
This works 2 letter columns (up until column ZZ). You'd have to nest another if statement for 3 letter columns.
The formula above fails on columns AY, AZ and each of the following nY and nZ columns. The corrected formula is:
=IF(COLUMN()>26,CHAR(ROUNDDOWN((COLUMN()-1)/26,0)+64)&CHAR(MOD((COLUMN()-1),26)+65),CHAR(COLUMN()+64)
Ruby one-liner:
def column_name_for(some_int)
some_int.to_s(26).split('').map {|c| (c.to_i(26) + 64).chr }.join # 703 => "AAA"
end
It converts the integer to base26 then splits it and does some math to convert each character from ascii. Finally joins 'em all back together. No division, modulus, or recursion.
Fun.
FROM wcm:
If you don't want to use VBA, you can use this
replace colnr with the number you want
=MID(ADDRESS(1,colnr),2,LEN(ADDRESS(1,colnr))-3)
Please be aware of the fact that this formula is volatile because of the usage of the ADDRESS function. Volatile functions are functions that are recalculated by excel after EVERY change.
Normally excel recalculates formula's only when their dependent references changes.
It could be a performance killer, to use this formula.
And here is a conversion from the VBScript version to SQL Server 2000+.
CREATE FUNCTION [dbo].[GetExcelColRef]
(
#col_seq_no int
)
RETURNS varchar(5)
AS
BEGIN
declare #Result varchar(5)
set #Result = ''
set #col_seq_no = #col_seq_no - 1
If (#col_seq_no >= 0 And #col_seq_no < 26)
BEGIN
set #Result = char(65 + #col_seq_no)
END
ELSE
BEGIN
set #Result = [dbo].[GetExcelColRef] (#col_seq_no / 26) + '' + [dbo].[GetExcelColRef] ((#col_seq_no % 26) + 1)
END
Return #Result
END
GO
This works fine in MS Excel 2003-2010. Should work for previous versions supporting the Cells(...).Address function:
For the 28th column - taking columnNumber=28; Cells(1, columnNumber).Address returns "$AB$1".
Doing a split on the $ sign returns the array: ["","AB","1"]
So Split(Cells(1, columnNumber).Address, "$")(1) gives you the column name "AB".
UPDATE:
Taken from How to convert Excel column numbers into alphabetical characters
' The following VBA function is just one way to convert column number
' values into their equivalent alphabetical characters:
Function ConvertToLetter(iCol As Integer) As String
Dim iAlpha As Integer
Dim iRemainder As Integer
iAlpha = Int(iCol / 27)
iRemainder = iCol - (iAlpha * 26)
If iAlpha > 0 Then
ConvertToLetter = Chr(iAlpha + 64)
End If
If iRemainder > 0 Then
ConvertToLetter = ConvertToLetter & Chr(iRemainder + 64)
End If
End Function
APPLIES TO: Microsoft Office Excel 2007 SE / 2002 SE / 2000 SE / 97 SE
I suppose you need VBA code:
Public Function GetColumnAddress(nCol As Integer) As String
Dim r As Range
Set r = Range("A1").Columns(nCol)
GetColumnAddress = r.Address
End Function
This does what you want in VBA
Function GetNthExcelColName(n As Integer) As String
Dim s As String
s = Cells(1, n).Address
GetNthExcelColName = Mid(s, 2, InStr(2, s, "$") - 2)
End Function
This seems to work in vb.net
Public Function Column(ByVal pColumn As Integer) As String
pColumn -= 1
If pColumn >= 0 AndAlso pColumn < 26 Then
Return ChrW(Asc("A"c) + pColumn).ToString
ElseIf (pColumn > 25) Then
Return Column(CInt(math.Floor(pColumn / 26))) + Column((pColumn Mod 26) + 1)
Else
stop
Throw New ArgumentException("Invalid column #" + (pColumn + 1).ToString)
End If
End Function
I took Joseph's and tested it to BH, then fed it 980-1000 and it looked good.
In VBA, assuming lCol is the column number:
function ColNum2Letter(lCol as long) as string
ColNum2Letter = Split(Cells(1, lCol).Address, "$")(0)
end function
All these code samples that these good people have posted look fine.
There is one thing to be aware of. Starting with Office 2007, Excel actually has up to 16,384 columns. That translates to XFD (the old max of 256 colums was IV). You will have to modify these methods somewhat to make them work for three characters.
Shouldn't be that hard...
Here's Gary Waters solution
Function ConvertNumberToColumnLetter2(ByVal colNum As Long) As String
Dim i As Long, x As Long
For i = 6 To 0 Step -1
x = (1 - 26 ^ (i + 1)) / (-25) - 1 ‘ Geometric Series formula
If colNum > x Then
ConvertNumberToColumnLetter2 = ConvertNumberToColumnLetter2 & Chr(((colNum - x - 1)\ 26 ^ i) Mod 26 + 65)
End If
Next i
End Function
via http://www.dailydoseofexcel.com/archives/2004/05/21/column-numbers-to-letters/
Considering the comment of wcm (top value = xfd), you can calculate it like this;
function IntToExcel(n: Integer); string;
begin
Result := '';
for i := 2 down to 0 do
begin
if ((n div 26^i)) > 0) or (i = 0) then
Result := Result + Char(Ord('A')+(n div (26^i)) - IIF(i>0;1;0));
n := n mod (26^i);
end;
end;
There are 26 characters in the alphabet and we have a number system just like hex or binary, just with an unusual character set (A..Z), representing positionally the powers of 26: (26^2)(26^1)(26^0).
FYI T-SQL to give the Excel column name given an ordinal (zero-based), as a single statement.
Anything below 0 or above 16,383 (max columns in Excel2010) returns NULL.
; WITH TestData AS ( -- Major change points
SELECT -1 AS FieldOrdinal
UNION ALL
SELECT 0
UNION ALL
SELECT 25
UNION ALL
SELECT 26
UNION ALL
SELECT 701
UNION ALL
SELECT 702
UNION ALL
SELECT 703
UNION ALL
SELECT 16383
UNION ALL
SELECT 16384
)
SELECT
FieldOrdinal
, CASE
WHEN FieldOrdinal < 0 THEN NULL
WHEN FieldOrdinal < 26 THEN ''
WHEN FieldOrdinal < 702 THEN CHAR (65 + FieldOrdinal / 26 - 1)
WHEN FieldOrdinal < 16384 THEN CHAR (65 + FieldOrdinal / 676 - 1)
+ CHAR (65 + (FieldOrdinal / 26) - (FieldOrdinal / 676) * 26 - 1)
ELSE NULL
END
+ CHAR (65 + FieldOrdinal % 26)
FROM TestData
ORDER BY FieldOrdinal
I currently use this, but I have a feeling that it can be optimized.
private String GetNthExcelColName(int n)
{
String firstLetter = "";
//if number is under 26, it has a single letter name
// otherwise, it is 'A' for 27-52, 'B' for 53-78, etc
if(n > 26)
{
//the Converts to double and back to int are just so Floor() can be used
Double value = Convert.ToDouble((n-1) / 26);
int firstLetterVal = Convert.ToInt32(Math.Floor(value))-1;
firstLetter = Convert.ToChar(firstLetterValue + 65).ToString();
}
//second letter repeats
int secondLetterValue = (n-1) % 26;
String secondLetter = Convert.ToChar(secondLetterValue+65).ToString();
return firstLetter + secondLetter;
}
=CHAR(64+COLUMN())