About using Double quotes in Vbscript

I have a very basic doubt in vb scripting:

Msgbox "This is myName" ' This works fine

Msgbox "This is "myName""  ' This gives an error

Msgbox "This is ""myName"""   'This works fine

My question is if I need to save (in a variable) or display string with double quotes why I need to use a doble quotes twice for the word or phrase. Does using a common double quotes doesn't mean I want to display the entire thing or could be saved as string in variable?

Solution 1:

In VBScript, string literals are surrounded by double quotes ("). This is what your first example shows:

Msgbox "This is myName" ' This works fine

However, if you want to include a double quote character inside of your string literal, you've got a problem, because VBScript is going to interpret the second double quote character it finds as signifying the end of the string literal. This is what your second example shows:

Msgbox "This is "myName""  ' This gives an error
                       ^   ' because it prematurely terminates the string here
                           ' and doesn't know what to do with the trailing "

Fortunately, there's an escape hatch. It involves escaping the double quote character with another character, indicating that VBScript should process it as a literal double quote character, rather than a magical "end-of-string-literal" character. It just so happens that the escape character VBScript uses is a double quote character. This is what your second example shows:

Msgbox "This is ""myName"""   'This works fine

• You begin the string with a single double-quote, indicating the start of a string literal.
• Then you want to have an embedded double quote character, so you use two of them. This is where the escaping starts: you escape the double quote character with another double quote character.
• Then you do that escaping thing again.
• Finally, you terminate the entire string literal with another double quote character.

Other languages often use a backslash (\) as the escape character. That might make things easier to see. Assuming VBScript used a backslash as the escape character rather than a double quote, your code would look like this:

Msgbox "This is \"myName\""   ' doesn't work in VBScript; example only

If this syntax bothers you, you can declare a constant for the double quote and use that each time:

Const Quote = """"

' ... later in the code ...

Msgbox "This is " & Quote & "myName" & Quote

Solution 2:

Each language has its own escape character. By chance or not, in VB/VBS it is double quote-mark. And also by chance or not, we can embed only double quote in literal string. We cannot embed other special characters as Tab for example.

However, using VB/VBS escape character simplify our coding.

str = """D:\path\to\xyz.exe"" ""arg 1"" ""arg 2"""
WScript.Echo str  ' "D:\path\to\xyz.exe" "arg 1" "arg 2"

str = Chr(34) & "D:\path\to\xyz.exe" & Chr(34) & " " _
    & Chr(34) & "arg 1" & Chr(34) & " " & Chr(34) & "arg 2" & Chr(34)
WScript.Echo str  ' "D:\path\to\xyz.exe" "arg 1" "arg 2"

str = Join(Array("", "D:\path\to\xyz.exe", " ", "arg 1", " ", "arg 2", ""), Chr(34))
WScript.Echo str  ' "D:\path\to\xyz.exe" "arg 1" "arg 2"

But personally I prefer using Replace as it make my code more readable.

str = Replace("'D:\path\to\xyz.exe' 'arg 1' 'arg 2'", Chr(39), Chr(34))
WScript.Echo str  ' "D:\path\to\xyz.exe" "arg 1" "arg 2"

You can use Replace (if that convenient to you) and for the rest special characters.

str = Replace(Replace("A|B|C!1|2|3", "!", vbNewLine), "|", vbTab)
WScript.Echo str
'A  B   C
'1  2   3

Solution 3:

String literals have to be delimited to separate what you what in the string from the outside. The string delimiter in VBScript is " (double quote). Other languages use " too, some have ' (single quote) as an alternative or a delimiter with a slightly different semantic.

To contain the delimiter in a string literal it has to be escaped (marked as not meaning 'end' or 'begin' of the string. The escape marker for " in string literals is " . giving "" - in VBscript. Other languages use \" to escape a double quote.

So

Msgbox "This is ""myName"""   'This works fine
x = "This is ""myName"""

is correct VBScript if you what to display (or store) This is "myName".

Solution 4:

Double quotes in VBScript enclose a string. If you insert a single double qoute inside a string it terminates the string prematurely and the remainder causes an error. Because of that you must escape double quotes inside a string, which can be done by doubling them. That's why your 3^rd command works while your 2^nd doesn't.