The
Debug.Print examples so far have been quite
simple—
Debug.Print followed by a message statement—but
the syntax of the message can be somewhat more elaborate than simple text.
For one thing, the position in which the message appears in the Immediate window
can be specified by preceding the message text with VB’s
Spc() or Tab() functions. If you want to indent
a message by 10 spaces, you could do so in either of two ways:
Debug.Print Spc(10) "This message is preceded by ten spaces."
or:
Debug.Print Tab(11) "This message begins on column eleven, which is functionally
identical."
Obviously, Spc() inserts spaces in the output, and
Tab() sets the position where the next message will appear.
It is also possible to use more than one text expression on the same line:
Dim sDebugMsg as String
sDebugMsg = " will self-destruct in five seconds, Mr.
Phelps."
Debug.Print "This message" & sDebugMsg
When you need to combine multiple text expressions for use with a single Debug.Print
statement, the syntax starts to get a bit cluttered. After each text expression,
you can tell VB where to put the next
expression. There are three ways to do this.
First, you can place a semicolon after a text expression. This puts the insertion
point immediately after the last character displayed.
That is, the first character in the next expression that prints will be immediately
after the last character in the expression preceding the semicolon. For all practical
purposes, this behavior makes the semicolon act just like the "&"
concatenation operator. In fact, the last line of the preceding example could
have been written like this:
Debug.Print "This message"; sDebugMsg
Second, you can use the Tab() function to move the
insertion point to a specific column. If you want some space between your messages,
you might try something like this (if you have an exceptionally wide screen):
Debug.Print "That’s one small step for man"; Tab(100); ";
one mighty leap for VB"
What happens if you specify a Tab position that would cause part of the previous
text expression to be overwritten? The first text expression in the preceding
example is 29 characters long, for example. What happens if you enter this?
Debug.Print "That’s one small step for man"; Tab(11); ";
one mighty leap to the next line for VB"
You might expect the output in the Immediate window to look like "That’s
one;one mighty leap to the next line for VB", starting the second text expression
in column 11 of the same line. In fact, VB saves you from such mistakes by moving
the second expression to column 11 of the next line.
Finally, you can use Tab with no argument (remember to omit the parentheses
too; otherwise, VB will generate a syntax error) to position the insertion point
at the beginning of the next print zone. (On average, a print zone occurs about
every 14 columns.)
Remember that all the semicolons and Tabs are optional. If you don’t
specify where to place the next character, it will print on the next line. You
can use these formatting rules to produce output in a variety of ways. However,
this example should give you some idea of how to combine them. Figure 18.15 shows
the result:
LISTING 18.3
THE Debug.Print MESSAGE
Private Sub cmdOK_Click()
Dim sRef As String, sMsg1 As String, sMsg2 As String
sRef = "12345678901234567890123456789012345678901234567890"
sMsg1 = "I am a string exactly 40 characters long"
sMsg2 = "followed by more text at column 46."
Debug.Print sRef
Debug.Print sMsg1; Spc(5); sMsg2
Debug.Print sMsg1; Tab(46); sMsg2
Debug.Print sMsg1; Tab(Len(sMsg1) + 6); sMsg2; vbCr
Debug.Print "The End!"
End Sub
FIGURE 18.15 The output of the Debug.Print formatting example looks like this.
Among other things, notice how it is legal to use a function call and calculations
in the Debug.Print line. The Len()
function determines how long the sMsg1 string
is, and then you add another six columns to that to duplicate the output of the
other lines. Why is there an empty line just before "The End!"? That’s
because there isn’t a position specifier after the vbCr
constant (yes, built-in constants are available, too). You didn’t
specify where to place the next character, so it printed on the next line following
vbCr.
NOTE - How VB Treats Consecutive Debug.Print Text Expressions:
If you try to place two Debug.Print text expressions immediately after one another,
VB will insert a semicolon between them for you. In other words, if you type:
Debug.Print "Message #1"
"Message #2"
As soon as you press Enter to move to the next line, VB will automatically change
your debugging message into this:
Debug.Print "Message #1";
"Message #2"
