How to show long numbers in Excel?

Question

I have to build a C# program that makes CSV files and puts long numbers (as string in my program). The problem is, when I open this CSV file in Excel the numbers appear like

Answer 1

When I generate data to imported into Excel, I do not generate a CSV file if I want control over how the data are displayed. Instead, I write out an Excel file where the properties of the cells are set appropriately. I do not know if there is a library out there that would do that for you in C# without requiring Excel to be installed on the machine generating the files, but it is something to look into.