Untitled

Using if clause inside Regular Expression
"Mary have banana. Mary have apple. Mary have NO pear."

mary have (.+?.)+?

Maryshaves(?!NO)(S*)

(?(bob)[a-z]+|[0-9]+)

(?(?<!s)[a-z]+|[0-9]+)

string sentence = "Mary have banana Mary have apple Mary have NO pear";
    if (sentence.Contains("banana"))
    {
        string x= sentence.Remove(sentence.IndexOf("banana"),"banana".Length);
    }

sentence = "Mary have banana Mary have apple Mary have NO pear";
string[] brokenUp = sentence.Split(
      new String[]
      {
          "first fruit as string variable",
          "second fruit as string variable",
          "third fruit as string variable"
      },
      StringSplitOptions.None
);
string newSentence = null;
for (int i = 0; i < brokenUp.Length; i++)
{
    newSentence += brokenUp[i];
}