GetSheetName doesn't work on this excel

[EP-Toushirou]

Description

GetSheetName doesn't work on this excel (other excels are no problem)
GetSheetName.xlsx

func ReadExcelFile(){
	f, err := excelize.OpenFile("./GetSheetName.xlsx")
	if err != nil {
		Println(err)
		return
	}

	fmt.Println(f.GetSheetName(1))
}

Steps to reproduce the issue:
1.Open the excel and read it and you can find it can't get the result "Sheet1",it got a empty string

Output of go version:
1.12.7

Excelize version or commit ID:
2019.08.04 update github

Environment details (OS, Microsoft Excel™ version, physical, etc.):
win10 1903
office 2019(but i don't know who create this excel and his excel version, it's on our svn)

[mlh758]

This opens fine for me on MacOS. "./GetSheetName.xlsx" doesn't look like valid path syntax on Windows.

[EP-Toushirou]

you can test it on windows, other excels are no problem, but i don't know why this excel cannot get the sheet name. @mlh758

[mlh758]

Okay yeah I can reproduce this. GetSheetName looks for a sheet with an ID that matches the index. This presumably assumes that the IDs on the sheets are in order. The only sheet in this excel document has an ID of 5.

[mlh758]

It looks like changing the sheet order changes the order sheets appear within the <sheets> tag within workbook.xml. @xuri I think GetSheetName can be simplified to just check the index of the sheet against the Sheets field in a workbook.

[mlh758]

Go ahead and pull down the code from this PR and let me know if that fixes your issue.

[EP-Toushirou]

@mlh758 yes, it can slove the problem.thank you.