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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /** Answer to Stackoverflow question:
  8.  * https://stackoverflow.com/questions/64685241/why-does-col-variable-return-a-wrong-value
  9.  */
  10. class Ideone
  11. {
  12.  
  13.     public static long toColumnNumber(String columnLabel) {
  14.         final int asciiOffset = (int) 'A' - 1; // 64 = 65 - 1, so that (int) 'B' - asciiOffset == 2
  15.         long columnNumber = 0;
  16.  
  17.         for (int backwardsIndex=0; backwardsIndex < columnLabel.length(); backwardsIndex++) {
  18.             char letter = columnLabel.charAt(columnLabel.length() - backwardsIndex -1);
  19.             int letterAsNumber = (int) letter - asciiOffset;
  20.             columnNumber += Math.pow(26, backwardsIndex) * letterAsNumber;
  21.         }
  22.  
  23.         return columnNumber;
  24.     }
  25.  
  26.     public static void main (String[] args) throws java.lang.Exception
  27.     {
  28.         final String A = "A";
  29.         System.out.println(A + " should be 1, is: " + toColumnNumber(A));
  30.         final String AA = "AA";
  31.         System.out.println(AA + " should be 27, is: " + toColumnNumber(AA));
  32.         final String ZZ = "ZZ";
  33.         System.out.println(ZZ + " should be 702, is: " + toColumnNumber(ZZ));
  34.  
  35.  
  36.         assert toColumnNumber("AUHS") == 31999L;
  37.     }
  38. }
Success #stdin #stdout 0.08s 33984KB
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Standard input is empty
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A should be 1, is: 1
AA should be 27, is: 27
ZZ should be 702, is: 702
https://ideone.com/2Pn8Jo
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
public

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