In Excel, the columns are identified by
a b c .... z aa ab ac .... az ba bb bc .... yz za zb zc .... zz aaa aab aac ....
These identifications correspond to the numerical values as
1 2 3 .... 26 27 28 29 .... 52 53 54 55 .... 676 677 678 679 .... 702 703 704 705 ....
How to write a C++ code that can perform the bilateral conversion between these two different identification schemes?