Fastest function to generate Excel column letters in C#

Question

What is the fastest c# function that takes and int and returns a string containing a letter or letters for use in an Excel function? For example, 1 returns \"A\", 26 return

Answer 1

The code I'm providing is NOT C# (instead is python) but the logic can be used for any language.

Most of previous answers are correct. Here is one more way of converting column number to excel columns. solution is rather simple if we think about this as a base conversion. Simply, convert the column number to base 26 since there is 26 letters only. Here is how you can do this:

steps:

• set the column as a quotient

• subtract one from quotient variable (from previous step) because we need to end up on ascii table with 97 being a.

• divide by 26 and get the remainder.

• add +97 to remainder and convert to char (since 97 is "a" in ASCII table)
• quotient becomes the new quotient/ 26 (since we might go over 26 column)
• continue to do this until quotient is greater than 0 and then return the result

here is the code that does this :)

def convert_num_to_column(column_num):
    result = ""
    quotient = column_num
    remainder = 0
    while (quotient >0):
        quotient = quotient -1
        remainder = quotient%26
        result = chr(int(remainder)+97)+result
        quotient = int(quotient/26)
    return result

print("--",convert_num_to_column(1).upper())