Replace string spaces with an underscore

Question

I need to replace some spaces with an underscore (i.e. "PM HD PSP" > "PM_HD_PSP")

Here's what I've tried so far:

private string NombreExcel3(string excel)
{
    MessageBox.Show(excel);

    excel.Replace(' ','_');

    MessageBox.Show(excel);
    return excel;
}

Answer 1

Strings are immutable, you need to do:

excel = excel.Replace(' ','_');

String.Replace() wont alter the original string, it will instead return a new altered string.

String.Replace(): Returns a new string in which all occurrences of a specified Unicode character or String in the current string are replaced with another specified Unicode character or String.

Answer 2

string.Replace(...) returns a new string object without modifying the original one

So you should do :

excel = excel.Replace(' ','_');

Answer 3

You need to set excel to the replaced version.

excel = excel.Replace(' ','_');

Answer 4

excel = excel.Replace(' ','_');

Replace does not change the string on place.