Find Excel column name from a given column number

• Difficulty Level : Medium
• Last Updated : 08 Oct, 2021

MS Excel columns have a pattern like A, B, C, …, Z, AA, AB, AC, …., AZ, BA, BB, … ZZ, AAA, AAB ….. etc. In other words, column 1 is named as “A”, column 2 as “B”, column 27 as “AA”.
Given a column number, find its corresponding Excel column name. The following are more examples.

Input          Output
26             Z
51             AY
52             AZ
80             CB
676            YZ
702            ZZ
705            AAC

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

Thanks to Mrigank Dembla for suggesting the below solution in a comment.
Suppose we have a number n, let’s say 28. so corresponding to it we need to print the column name. We need to take the remainder with 26.

If remainder with 26 comes out to be 0 (meaning 26, 52, and so on) then we put ‘Z’ in the output string and new n becomes n/26 -1 because here we are considering 26 to be ‘Z’ while in actuality it’s 25th with respect to ‘A’.

Similarly, if the remainder comes out to be non-zero. (like 1, 2, 3, and so on) then we need to just insert the char accordingly in the string and do n = n/26.

Finally, we reverse the string and print.

Example:
n = 700
The remainder (n%26) is 24. So we put ‘X’ in the output string and n becomes n/26 which is 26.
Remainder (26%26) is 0. So we put ‘Z’ in the output string and n becomes n/26 -1 which is 0.

Following is the implementation of the above approach.

C++

 // C++ program to find Excel// column name from a given// column number#include #define MAX 50using namespace std; // Function to print Excel column name for a given column numbervoid printString(int n){    char str[MAX]; // To store result (Excel column name)    int i = 0; // To store current index in str which is result     while (n > 0) {        // Find remainder        int rem = n % 26;         // If remainder is 0, then a 'Z' must be there in output        if (rem == 0) {            str[i++] = 'Z';            n = (n / 26) - 1;        }        else // If remainder is non-zero        {            str[i++] = (rem - 1) + 'A';            n = n / 26;        }    }    str[i] = '\0';     // Reverse the string and print result    reverse(str, str + strlen(str));    cout << str << endl;     return;} // Driver program to test above functionint main(){    printString(26);    printString(51);    printString(52);    printString(80);    printString(676);    printString(702);    printString(705);    return 0;}

Java

 // Java program to find Excel// column name from a given// column number public class ExcelColumnTitle {    // Function to print Excel column    // name for a given column number    private static void printString(int columnNumber)    {        // To store result (Excel column name)        StringBuilder columnName = new StringBuilder();         while (columnNumber > 0) {            // Find remainder            int rem = columnNumber % 26;             // If remainder is 0, then a            // 'Z' must be there in output            if (rem == 0) {                columnName.append("Z");                columnNumber = (columnNumber / 26) - 1;            }            else // If remainder is non-zero            {                columnName.append((char)((rem - 1) + 'A'));                columnNumber = columnNumber / 26;            }        }         // Reverse the string and print result        System.out.println(columnName.reverse());    }     // Driver program to test above function    public static void main(String[] args)    {        printString(26);        printString(51);        printString(52);        printString(80);        printString(676);        printString(702);        printString(705);    }} // This code is contributed by Harikrishnan Rajan

Python

 # Python program to find Excel column name from a# given column number MAX = 50 # Function to print Excel column name# for a given column numberdef printString(n):     # To store result (Excel column name)    string = ["\0"] * MAX     # To store current index in str which is result    i = 0     while n > 0:        # Find remainder        rem = n % 26         # if remainder is 0, then a        # 'Z' must be there in output        if rem == 0:            string[i] = 'Z'            i += 1            n = (n / 26) - 1        else:            string[i] = chr((rem - 1) + ord('A'))            i += 1            n = n / 26    string[i] = '\0'     # Reverse the string and print result    string = string[::-1]    print "".join(string) # Driver program to test the above FunctionprintString(26)printString(51)printString(52)printString(80)printString(676)printString(702)printString(705) # This code is contributed by BHAVYA JAIN

C#

 // C# program to find Excel// column name from a given// column numberusing System; class GFG{     static String reverse(String input){    char[] reversedString = input.ToCharArray();    Array.Reverse(reversedString);    return new String(reversedString);} // Function to print Excel column// name for a given column numberprivate static void printString(int columnNumber){         // To store result (Excel column name)    String columnName = "";     while (columnNumber > 0)    {                 // Find remainder        int rem = columnNumber % 26;         // If remainder is 0, then a        // 'Z' must be there in output        if (rem == 0)        {            columnName += "Z";            columnNumber = (columnNumber / 26) - 1;        }                 // If remainder is non-zero        else        {            columnName += (char)((rem - 1) + 'A');            columnNumber = columnNumber / 26;        }    }     // Reverse the string    columnName = reverse(columnName);         // Print result    Console.WriteLine(columnName.ToString());} // Driver codepublic static void Main(String[] args){    printString(26);    printString(51);    printString(52);    printString(80);    printString(676);    printString(702);    printString(705);}} // This code is contributed by amal kumar choubey

Javascript


Output
Z
AY
AZ
CB
YZ
ZZ
AAC

Method 2
The problem is similar to converting a decimal number to its binary representation but instead of a binary base system where we have two digits only 0 and 1, here we have 26 characters from A-Z.
So, we are dealing with base 26 instead of base binary.
That’s not where the fun ends, we don’t have zero in this number system, as A represents 1, B represents 2 and so on Z represents 26.
To make the problem easily understandable, we approach the problem in two steps:

1. Convert the number to base 26 representation, considering we have 0 also in the system.
2. Change the representation to the one without having 0 in its system.

HOW? Here is an example

Step 1:
Consider we have number 676, How to get its representation in the base 26 system? The same way we do for a binary system, Instead of division and remainder by 2, we do division and remainder by 26.

Base 26 representation of 676 is : 100

Step2
But Hey, we can’t have zero in our representation. Right? Because it’s not part of our number system. How do we get rid of zero? Well it’s simple, but before doing that let’s remind one simple math trick:

Subtraction:
5000 - 9, How do you subtract 9 from 0 ? You borrow
from next significant bit, right.
• In a decimal number system to deal with zero, we borrow 10 and subtract 1 from the next significant.
• In Base 26 Number System to deal with zero, we borrow 26 and subtract 1 from the next significant bit.

So Convert 10026 to a number system that does not have ‘0’, we get (25 26)26
Symbolic representation of the same is: YZ

Here is the implementation of the same:

C++

 #include using namespace std; void printString(int n){    int arr;    int i = 0;     // Step 1: Converting to number assuming    // 0 in number system    while (n) {        arr[i] = n % 26;        n = n / 26;        i++;    }     // Step 2: Getting rid of 0, as 0 is    // not part of number system    for (int j = 0; j < i - 1; j++) {        if (arr[j] <= 0) {            arr[j] += 26;            arr[j + 1] = arr[j + 1] - 1;        }    }     for (int j = i; j >= 0; j--) {        if (arr[j] > 0)            cout << char('A' + arr[j] - 1);    }     cout << endl;} // Driver program to test above functionint main(){    printString(26);    printString(51);    printString(52);    printString(80);    printString(676);    printString(702);    printString(705);    return 0;} // This code is contributed by Ankur Goel

Java

 import java.util.*; class GFG{ static void printString(int n){    int []arr = new int;    int i = 0;     // Step 1: Converting to number    // assuming 0 in number system    while (n > 0)    {        arr[i] = n % 26;        n = n / 26;        i++;    }     // Step 2: Getting rid of 0, as 0 is    // not part of number system    for(int j = 0; j < i - 1; j++)    {        if (arr[j] <= 0)        {            arr[j] += 26;            arr[j + 1] = arr[j + 1] - 1;        }    }     for(int j = i; j >= 0; j--)    {        if (arr[j] > 0)            System.out.print(                (char)('A' + arr[j] - 1));    }    System.out.println();} // Driver codepublic static void main(String[] args){    printString(26);    printString(51);    printString(52);    printString(80);    printString(676);    printString(702);    printString(705);}} // This code is contributed by amal kumar choubey

Python3

 def printString(n):         arr =  * 10000    i = 0     # Step 1: Converting to number    # assuming 0 in number system    while (n > 0):        arr[i] = n % 26        n = int(n // 26)        i += 1             #Step 2: Getting rid of 0, as 0 is    # not part of number system    for j in range(0, i - 1):        if (arr[j] <= 0):            arr[j] += 26            arr[j + 1] = arr[j + 1] - 1     for j in range(i, -1, -1):        if (arr[j] > 0):            print(chr(ord('A') +                  (arr[j] - 1)), end = "");     print(); # Driver codeif __name__ == '__main__':         printString(26);    printString(51);    printString(52);    printString(80);    printString(676);    printString(702);    printString(705); # This code is contributed by Princi Singh

C#

 using System;class GFG{ static void printString(int n){  int []arr = new int;  int i = 0;   // Step 1: Converting to  // number assuming 0 in  // number system  while (n > 0)  {    arr[i] = n % 26;    n = n / 26;    i++;  }   // Step 2: Getting rid of 0,  // as 0 is not part of number  // system  for(int j = 0; j < i - 1; j++)  {    if (arr[j] <= 0)    {      arr[j] += 26;      arr[j + 1] = arr[j + 1] - 1;    }  }   for(int j = i; j >= 0; j--)  {    if (arr[j] > 0)      Console.Write((char)('A' +                     arr[j] - 1));  }  Console.WriteLine();} // Driver codepublic static void Main(String[] args){  printString(26);  printString(51);  printString(52);  printString(80);  printString(676);  printString(702);  printString(705);}} // This code is contributed by 29AjayKumar

Javascript


Output
Z
AY
AZ
CB
YZ
ZZ
AAC

Method 3:

We can use recursive function which definitely reduces the time and  increase the efficiency:

Alphabets are in sequential order like : ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ’. You have experienced while using excel when you see columns and rows numbering are done in  Alphabetical ways.

Here’s How I purposefully think about the logic how  it is  arranged.

(In Mathematical  terms, [a , b ] means from ‘a’ to ‘b’).

[1,26] = [A,Z] (Understand by ‘1’ stands for ‘A’ and ’26” stands for “Z”). For [27,52] ,it will be like [AA,AZ], For [57,78] it will be [BA,BZ]

Logic is to append a Alphabet sequentially whenever it ends upto numbering at 26.

For example, if the  number is ’27’ which greater than  ’26’, then we simply need to divide by 26, we get the remainder as 1,We see “1” as “A” and can be recursively done.

we will be using python for this..

Algorithm is:

1. Take an array and Sort the letters from A to Z .(You can also use import string and string function to get “A to Z” in uppercase.)

2.If number is less than or equal to ’26’, simply get the letter from array and print it.

3.If it greater than 26 ,use Quotient  Remainder rule, if remainder is zero , there are 2 possible ways, if quotient is “1”,simply hash out the letter from index [r-1]( ‘r’ is remainder), else call out the function from the  num =(q-1) and append at front to the letter indexing [r-1].

4.If remainder not equals to “0”, call the function for the num = (q) and append at the front to the letter indexing [r-1].

The code concerned to this is:

Python3

 # Or you can simply take a string and perform this logic ,no issue i found in here.alpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'# defined a recursive function here.# if number is less than "26", simply hash out (index-1)# There are sub possibilities in possibilities,# 1.if remainder is zero(if quotient is 1 or not 1) and# 2. if remainder is not zero def num_hash(num):    if num < 26:        return alpha[num-1]    else:        q, r = num//26, num % 26        if r == 0:            if q == 1:                return alpha[r-1]            else:                return num_hash(q-1) + alpha[r-1]        else:            return num_hash(q) + alpha[r-1]  # Calling the function out here and printing the ALphabets# This code is robust ,work for any positive integer only.# You can try as much as you wantprint(num_hash(26))print(num_hash(51))print(num_hash(52))print(num_hash(80))print(num_hash(676))print(num_hash(702))print(num_hash(705))
Output
Z
AY
AZ
CB
YZ
ZZ
AAC

Related Article :
Find Excel column number from column title