刪除特定短語之前和特定短語之前的字符串中的所有內容

Question

我有一個字符串，我想刪除短語之前的所有內容，然後刪除不同短語之後的所有內容。即

myString = "words words words FIRSTPHRASE these words I want SECONDPHRASE but not these words" 

所以新的字符串將是"these words I want"。

Answer 1

使用String.Substring和String.IndexOf，它也開始索引的overload：

string myString = "words words words FIRSTPHRASE these words I want SECONDPHRASE but not these words"; 
string result = myString; 
int indexOfFirstPhrase = myString.IndexOf("FIRSTPHRASE"); 
if(indexOfFirstPhrase >= 0) 
{ 
    indexOfFirstPhrase += "FIRSTPHRASE".Length; 
    int indexOfSecondPhrase = myString.IndexOf("SECONDPHRASE", indexOfFirstPhrase); 
    if (indexOfSecondPhrase >= 0) 
     result = myString.Substring(indexOfFirstPhrase, indexOfSecondPhrase - indexOfFirstPhrase); 
    else 
     result = myString.Substring(indexOfFirstPhrase); 
} 

Demonstration

Answer 2

這樣的事情？

string theWordsIWant = Regex.Replace(myString, @"^.*?FIRSTPHRASE\s*(.*?)\s*SECONDPHRASE.*$", "$1"); 

Demonstration