Excel open 3 times and wont close until i use the task manag

Question

Hi Im pretty new to the C# language. Right now im writing a Programm to calculate different cable dimensioning. Till now everything just worked fine but now i realised that when i use the programm it opens me three times the excel process and will only close if i propperly close the programm. otherwise everytime i hit the calculate button it will add 3 more excel process to the allready 3. I'm using excel for all the constants i need for my calculation. I just cant find out where the Problem is so i thought you might help me. I know the style of my programming isnt very good even bad:-) but im no programmer and most of the stuff i have in my programm is from the internet because im an newby and dont know or understand some of that. So if you could help me finding the error i would be very thankfull. The comments and other stuff is written in german because thats my nativ language i hope this wont be a problem. I guess the error is because im trying befor i open the excel file to catch all possible exceptions with if and else. thank you

Sam Urai · Answer

Ok i solved the Problem by my self. At first i had to remove some of my open Excel function. Actually i opend the Excel 3 times in the Programm on different positions. so i just cut it together to one (i actually only needed two befor the third one was a mistake:-) ) But still i had the Problem that the excel operation wouldnt stop by it self and everytime i hit the calculate button one more excel showed up in the Taskmanager. So i searched the internet and found this: Open Excel: var ExcelApp = new Microsoft.Office.Interop.Excel.Application(); var workbook = ExcelApp.Workbooks.Open(myPath); var worksheet = workbook.ActiveSheet as Worksheet; then do stuff in it... And closing Excel again: workbook.Save(); workbook.Close(); ExcelApp.Quit(); Marshal.ReleaseComObject(ExcelApp); Marshal.ReleaseComObject(workbook); workbook = null; worksheet = null; ExcelApp = null; GC.GetTotalMemory(false); GC.Collect(); GC.WaitForPendingFinalizers(); GC.Collect(); GC.GetTotalMemory(true); with this Method one Excel operation is open as long as the Programm is running but everytime i hit the calculate button now an excel operation opens but closes right after it is done. Its not perfect but it will work like this:-)