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I think the idea is that you can look into the problem of converting a number in decimal to a number in base 26 system (in this case numbers are A through Z).

StringBuffer sb = new StringBuffer();
while(n >= 0){
char current = numbers[n % 26];
n = n / 26 - 1;
sb = (new StringBuffer(current)).append(sb);
}

return sb.toString();

Here numbers is a char array that has A through Z from 0 to 25.

char * get_column(int column_no)
{
char *str="";

while(column_no>=0)
{
int no = column_no%26;
column_no = column_no/26-1;
char temp = 'A'+ (char)no;
char *temp1 = (char *)malloc(sizeof(char)*2) ;
temp1[0]= temp;
temp1[1]='\0';
str =strcat(temp1,str);
}

return str;
}

Did any one get the pattern for this ? ..
No
26*1 = 1 char name
from 27 to 26*[26] = 2 char name
677 to 26 * 26 * [26] = 3 char name .. and so on ..
I am struggling to get ahead of this ..

Hi Rytis, 2 questions
1. For 890(=AHG), your code will generate the rightmost char as numbers[890%26]=numbers[6]=F, whereas the char should be G.
2. What is the reasoning behind the -1 in
n = n/26 - 1 ?

Thanks

Oops, missed the obvious. Never mind.

1. char temp = 'A'+ (char)no;
and devide with 26 and not 25.
that works i think.

Hi Everyone,

so why the (n = n/26 - 1) in Rytis's soln? Can anyone help out please?

Rytis solution was nice. Here is a recursive solution.

start the code with PrintSeq( c, 0, 0, 0, number);


PrintSeq( char a[], int h, int b, int num, int total) {

for (int i=0; i<26; i++) {
if (h > 0) {
c[h-1] = 'a' + b;
}
c[h] = alp[i];
num++;
if (num == total)
print(a) // The value in the array

}


if (b==25 || h==0) {
PrintSeq(c, h+1,0, num, total);
} else {
PrintSeq(c, h, b+1, num, total);
}
}

@Rytis - Impressive!

@Rytis

I am not very sure about the response by him . Let me give this by a small example

Rytis Code:

StringBuffer sb = new StringBuffer();
while(n >= 0){
char current = numbers[n % 26];
n = n / 26 - 1;
sb = (new StringBuffer(current)).append(sb);
}

return sb.toString();



StringBuffer sb = new StringBuffer();
if(n >= 0)
{
char current = number[n % 26];
// Now you have the current character.
// Find the number of times to append that charater
int times = n / 26 ;
while(times >= 0 )
{
sb = (new StringBuffer(current)).append(sb);
times = times - 1;
}
return sb.toString();
}


With example : If we have 53 as the integer given : Answer should be "BBB"

times = 53 / 26;
times = 2
We have the charater as from the number array as "B"

So it will return "BBB"

I believe this works perfect. The logic is in counting, we would do 0-9 and the next number will be 10 and not 00. The logic Excel columns would do is 0-9 and 00, 01, 02 etc..

void ConvertToExcelColumn(int number, char * a)
{
char *ptr = a;
int n=0;

n = number%26;
*ptr = 'A' + n;
ptr++;
number = number/26;

while(number)
{
n = number%26;
*ptr = 'A' + n - 1;
ptr++;
number = number/26;
}

*ptr = '\0';

reverse(a);
}

Excel allows column names only till IV and so my code works fine! :)

public string ExcelColumnPrint(int number)
{
char[] aryABC = new char[] {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
int bcNumber = number;
int bcNumber2 = number;
int reminder = 0;
Stack st = new Stack();
string column = string.Empty;

while (number > 25)
{
number = number / 26;
reminder = bcNumber % 26;
bcNumber = number;
st.Push(aryABC[reminder]);
}

if (bcNumber2 < 26)
st.Push(aryABC[number]);
else
st.Push(aryABC[number-1]);

while (st.Count > 0)
{
column += st.Pop().ToString();
}
return column;
}

Little improvement:

public string ExcelColumnPrint(int number)
{
char[] aryABC = new char[] {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
int bcNumber = number;
int reminder = 0;
StringBuilder sb = new StringBuilder();
string column = string.Empty;

while (number > 25)
{
reminder = number % 26;
number = number / 26;
sb.Insert(0, aryABC[reminder]);
}

if (bcNumber < 26)
sb.Insert(0, aryABC[number]);
else
sb.Insert(0, aryABC[number-1]);

return sb.ToString();
}

one can also ask following:
// Find the starting point of given digit
public int ExcelColumnSequenceStartPoint(int digit)
{
if (digit == 1) return 0;
int SeqStartPoint = 1;
while (digit-1 > 0)
{
SeqStartPoint = SeqStartPoint * 26;
digit--;
}
return SeqStartPoint;
}


// Find the range of given digit
public string ExcelSequenceRange(int digit)
{
return ExcelColumnSequenceStartPoint(digit).ToString() + " to " + string.Format("{0}",

(ExcelColumnSequenceStartPoint(digit+1) - 1));
}

The question I was asked was mapping from 1 .. 25 26 .. to A .. Z AA AB ... So the base is 1, not 0.

Then equation should be :
outChar = (n - 1) % 26 + 'A';
n = n / 26;

Prepare for being asked this.

Sorry, should be
outChar = (n - 1) % 26 + 'A';
n = (n - 1) / 26;

to map from 1 .. 25 26 .. to A .. Z AA AB ...

#include<iostream>
#include<string>
using namespace std;

string Translate(int N){
int n=N+1, m;
string a="";
do{
m=n%26;
n=n/26;
a.insert(a.begin(), m-1+'A');
}while(n);
return a;
}

void main(){
int num;
cout<<"Input an integer: ";
cin>>num;
cout<<"\n"<<Translate(num)<<" ";
}

Java flavor

int colnumber =1705;
		int more;
		int confirm;
		StringBuilder answer = new StringBuilder();
		more = colnumber/26;
		confirm = colnumber % 26;
		confirm = confirm  == 0 ? 26 : confirm;
		answer.insert(0, columnNames[confirm]);
		while(more > 26) {
			more = more/26;
			confirm = more % 26;
			answer.insert(0, columnNames[confirm]);
		}
		answer.insert(0, columnNames[more]);
		
		System.out.println(answer.toString());

no solution is correct till now

see the no :-
0 25 26 -----------------701 702.....728......754.....780
a---z aa zz aaa.. aba.. aca.. ada ..

no of algo work this way.

for code :

1) find out the bigger interval which the no number fills
that is 26 + 26*26 + 26*26*26
2) then take this many char as the interval no intialize them to 'A'

3) then take mode 26 and add in 'A' .

got the Idea ..if no then use some brain.

char * extractColumn( int pos){

char *ptr;
char *ptrindex;
ptrindex = ptr;
// allocate some size to this string..
// Take some #define value
struct columnSet cSet;
while ( pos > 0) {
*(ptrindex) = pos%26 + 'A';
ptrindex++;
pos = pos/26;
}
*ptr = '\0';
return strrev(ptr);
}

#include <stdio.h>

char * getB26(int num) {
	int temp = 0, cnt = 1, curr = num, i; 
	char * result;
	if (num < 1) return NULL;
	temp = 26;
	//find the interval
	while(num >=  temp) {
		num = num - temp;
		temp = temp * 26;
		cnt++;
	}
	result = (char *)malloc(cnt + 1);
	result[cnt] = 0;
	for(i = 0; i < cnt; i++)
		result[i] = 'A';
	while(num) {
		temp = num % 26;
		num = num/26;
		result[--cnt] = 'A' + temp;
	}
	return result;
}

int main(){
	char * res = getB26(780); //prints ADA
}