JavaScript: Excel column title related with a column number

JavaScript Math: Exercise-97 with Solution

Excel Column Title from Number

Write a JavaScript program to retrieve the Excel column title associated with a given column number (integer value).

For example:
1 -> A
2 -> B
3 -> C
...
26 -> Z
27 -> AA
28 -> AB
...

Test Data:
(3) -> C
(27) -> AA
( 151) -> EU

Sample Solution-1:

JavaScript Code:

/**
 * Function to convert a column number to its corresponding Excel column title.
 * @param {number} n - The column number.
 * @returns {string} - The Excel column title.
 */
function test(n) {
  s = 1; // Start index for column titles (A = 1)
  e = 26; // End index for column titles (Z = 26)
  result = ""; // Initialize the result variable to store the column title
  while ((n -= s) >= 0) { // Loop until the column number is greater than or equal to the start index
        result = String.fromCharCode(parseInt((n % e) / s) + 65) + result; // Calculate the character for the current digit and prepend it to the result
        s = e; // Update the start index for the next digit
        e *= 26; // Update the end index for the next digit
    }
  return result; // Return the Excel column title
}

// Test cases
let n = 4;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n));

n = 27;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n));

n = 151;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n)); 

Output:

n = 4
Excel column title related with the said column number: D
n = 27
Excel column title related with the said column number: AA
n = 151
Excel column title related with the said column number: EU

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-97 by w3resource (@w3resource) on CodePen.

Sample Solution-2:

JavaScript Code:

/**
 * Function to convert a column number to its corresponding Excel column title.
 * @param {number} n - The column number.
 * @returns {string} - The Excel column title.
 */
function test(n) {
    result = ''; // Initialize the result variable to store the Excel column title
    while(n > 0){ // Loop until n becomes 0
        el = String.fromCharCode(65 + (n-1) % 26); // Calculate the character corresponding to the current digit
        result = el + result; // Prepend the character to the result
        n = ~~((n-1)/26); // Update n to get the next digit
    }
    return result; // Return the Excel column title
}
// Test cases
n = 4;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n));

n = 27;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n));

n = 151;
console.log("n = " + n);
console.log("Excel column title related with the said column number: " + test(n));

Output:

n = 4
Excel column title related with the said column number: D
n = 27
Excel column title related with the said column number: AA
n = 151
Excel column title related with the said column number: EU

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-97-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that converts a given positive integer to its corresponding Excel column title using modulus and division.
• Write a JavaScript function that iteratively builds the Excel column title by mapping remainders to letters.
• Write a JavaScript function that validates the input and returns an error if the column number is not a positive integer.
• Write a JavaScript function that handles edge cases where the column number requires multiple letters, such as 27 or above.

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