Question

I have a string as below.

string data = "A := B;\nC:=D";

The string has to be replaced with SET statement as below.

data = "SET A=B;\nSET C=D"

It should replace := with =and insert aSET` statement.

I came out with an algorithm as below but it’s not working when I have multiple :=.

Is there any other easiest and efficient way to handle this? Perhaps using RegEx?

private string AddSETStatement(string script)
{
        script = script.Replace(": =", ":=");
        script = script.Replace(":=", ":= ");
        script = script.Replace(" :=", ":= ");
        int found = script.IndexOf(":=");
        while (found > -1)
        {
            int foundspace = -1;
            for (int index = found; index >= 0; index--)
            {
                string temp = script.Substring(index, 1);
                if (temp == " ")
                {
                    foundspace = index;
                    break;
                }
            }
            script = script.Remove(found, 1);
            if (foundspace == -1)
            {
                script = "SET " + script;
            }
            else
            {
                script = script.Insert(foundspace, " SET ");
            }
            found = script.IndexOf(":=");
        }

        return script.Trim();
}

Any help would be appreciated.

Answer 1

I’ve tested this and I think this is the command that matches your requirement as you’ve coded your algorithm (which can be replaced with one line of code):

script = System.Text.RegularExpressions.Regex.Replace(script, 
     @"([A-Z]{1})[\s]{0,1}:[\s]{0,1}=[\s]{0,1}([A-Z]{1})", "SET $1=$2", 
     System.Text.RegularExpressions.RegexOptions.Multiline);

Just in case you actually use more than one space between and around := you can use this instead:

script = System.Text.RegularExpressions.Regex.Replace(script,
     @"([A-Z]{1})[\s]*:[\s]*=[\s]*([A-Z]{1})", "SET $1=$2", 
     System.Text.RegularExpressions.RegexOptions.Multiline);

This turns this:

A := B;
C:=D
    E: =F
G : = H
  I   :   =   K;

Into this:

SET A=B;
SET C=D
    SET E=F
SET G=H
  SET I=K;

And one more which handles variable names that are bother upper and lower case and contain numbers:

script = System.Text.RegularExpressions.Regex.Replace(script,
     @"([A-Za-z0-9]+)[\s]*:[\s]*=[\s]*([A-Za-z0-9]{1})", "SET $1=$2", 
     System.Text.RegularExpressions.RegexOptions.Multiline);

Turns this:

Alpha1 := Bravo2;
Char3le:=Delta9
    E1ch3: =Foxt343
golf : = h1
  I3   :   =   k;

Into:

SET Alpha1=Bravo2;
SET Char3le=Delta9
    SET E1ch3=Foxt343
SET golf=h1
  SET I3=k;

At least one those or a combination of those should be able to do the work for you.