LISP: Read a character from string?

Is there a current command to read a character from a string?

I am asking because I have a program that reads a TXT file I created; but I would like to put a few lines of comments at the beginning. I was thinking about starting it with a semicolon (typical) and then checking for it with my code.

I suppose I could try and test my .NET abilities and make a LISP function; but I wanted to check if there was an easier way first.

Can I check for a particular character?

Thanks.

Certainly,

Look into functions: vl-string-position, vl-string-search, substr

Could be (wcmatch string pattern)

You can use wildcard char like

(setq Pattern ";*")

It will return T if the line start with [;]

Thanks for the help. I will be looking into these.

you could use

(if(eq ";" (substr str 1 1))
 (princ (strcat "\n" str))
)

Is there a current command to read a character from a string?

 

I am asking because I have a program that reads a TXT file I created; but I would like to put a few lines of comments at the beginning. I was thinking about starting it with a semicolon (typical) and then checking for it with my code.

 

I suppose I could try and test my .NET abilities and make a LISP function; but I wanted to check if there was an easier way first.

 

Can I check for a particular character?

 

Thanks.

Here is VB.NET way

 
Imports System.IO
Imports System.Text
...........................
Sub try()
Dim strAppend As String = "This string is for appending"
Dim strFind As String = ";"
Dim strLine As String
Dim carret As String = Environment.NewLine
Dim sb As StringBuilder = New StringBuilder
Dim path As String = "C:\MyTextFile.txt"
Dim sr As System.IO.StreamReader = New System.IO.StreamReader(path)
Using sr
If System.IO.File.Exists(path) = True Then
sr = System.IO.File.OpenText(path)
Do While sr.Peek <> -1
strLine = sr.ReadLine()
If strLine.Contains(strFind) Then
sb.Append(strAppend & carret & strLine & carret)
Else
sb.Append(strLine & carret)
End If
Loop
Else
Return
End If
sr.Close()
End Using
Using sw As System.IO.StreamWriter = New StreamWriter(path)
sw.Write(sb.ToString())
End Using
End Sub

~'J'~